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Proceedings, 2018, ICEM 2018

The 18th International Conference on Experimental Mechanics (ICEM 2018)

Brussels, Belgium | 1–5 July 2018

Issue Editors:
Danny Van Hemelrijck, Vrije Universiteit Brussel, Belgium
Dimitrios Aggelis, Vrije Universiteit Brussel, Belgium
Nele De Belie, Ghent University, Belgium
Fabienne Delaunois, Université de Mons, Belgium
Thomas Geernaerts, Vrije Universiteit Brussel, Belgium
Patrick Guillaume, Los Alamos National Laboratory, USA
Anne Marie Habraken, University of Liège, Belgium
Patrick Hendrick, San Simon University, Bolivia
Edwin Reynders, KU Leuven, Belgium
Aude Simar, Université catholique de Louvain, Belgium
Steve Vanlanduit, University of Antwerp, Belgium

Number of Papers: 169

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Cover Story (view full-size image): Experimental mechanics play a crucial role in all stages of a material’s or structure’s life cycle, from research and design to production and use until liquidation or recycling. ICEM18, [...] Read more.

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6 pages, 404 KiB

Open AccessProceeding Paper

Early Detection of Damages Based on Comprehensive Theory of Deformation and Fracture

by Sanichiro Yoshida and Conor McGibboney

Proceedings 2018, 2(8), 354; https://doi.org/10.3390/ICEM18-05201 - 7 May 2018

Viewed by 2057

Numerical studies have been conducted based on the recently published Deformation Field Theory. Effects of pulling rates on displacement waves and volume expansion waves are analyzed in a finite element model (FEM) of a solid experiencing a uni-axial tensile load. Without relying on [...] Read more.

Numerical studies have been conducted based on the recently published Deformation Field Theory. Effects of pulling rates on displacement waves and volume expansion waves are analyzed in a finite element model (FEM) of a solid experiencing a uni-axial tensile load. Without relying on empirical data, the model’s numerical results demonstrate empirically known concepts that a fracture occurs more easily when the pulling rate is high, and the direction of external load is reversed. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 926 KiB

Open AccessProceeding Paper

Experimental Approach for Metals Mechanical Behavior Characterization at High Temperature: Development of a Complex Tensile Test Machine

by Arnaud Pignolet, Christelle Combeaud, Francis Fournier, Gilbert Fiorucci, Christophe Pradille, Yancheng Zhang, Aliz Pinto-Mora, Feng Gao and Michel Bellet

Proceedings 2018, 2(8), 355; https://doi.org/10.3390/ICEM18-05207 - 9 May 2018

Cited by 1 | Viewed by 1872

To characterize the mechanical behaviour at high temperature close to the melting point, a tensile test machine has been developed through resistive heating by Joule effect. A closed chamber is designed to control the working environment. By the two windows in the chamber, [...] Read more.

To characterize the mechanical behaviour at high temperature close to the melting point, a tensile test machine has been developed through resistive heating by Joule effect. A closed chamber is designed to control the working environment. By the two windows in the chamber, the temperature and displacement fields can be measured directly. For the machine, both temperature and tensile force can be controlled by the proportional-integral-derivative controller. In this paper, the main features of the machine’s design and development will be discussed, with a specific section dedicated to the optimization of the specimens’ shape, which is of utmost importance in the context of Joule heating. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 8665 KiB

Open AccessProceeding Paper

Dynamic Behavior of Metals at Elevated Temperatures and Ultra-High Strain Rates

by Tianxue Wang, Bryan Zuanetti and Vikas Prakash

Proceedings 2018, 2(8), 372; https://doi.org/10.3390/ICEM18-05204 - 7 May 2018

Cited by 1 | Viewed by 1751

This paper presents the results of a series of reverse geometry normal plate impact experiments designed to investigate the onset of incipient plasticity in commercial purity polycrystalline magnesium (99.9%) under weak uniaxial-strain shock compression loading and elevated temperatures up to the melting point [...] Read more.

This paper presents the results of a series of reverse geometry normal plate impact experiments designed to investigate the onset of incipient plasticity in commercial purity polycrystalline magnesium (99.9%) under weak uniaxial-strain shock compression loading and elevated temperatures up to the melting point of magnesium. To enable the characterization of dynamic material behavior under extreme conditions, i.e., ultra-high strain rates (~10⁶/s) and test temperatures up to sample melt (1000 °C), strategic modifications were made to the single-stage gas-gun facility at the Case Western Reserve University. In this configuration, thin metal samples (also representing the flyer plate), carried by a specially designed heat-resistant sabot, are heated uniformly across the diameter in a 100 mTorr vacuum prior to impact by a resistance coil heater at the breech end of the gun barrel. Moreover, a compact fiber-optics-based heterodyne normal displacement interferometer is designed and implemented to measure the normal component of the particle velocity history at the free surface of the target plate. Similar to the standard photonic Doppler velocimetry (PDV), this diagnostic tool is assembled using commercially available telecommunications hardware and uses a 1550-nm wavelength 2 W fiber-coupled laser, an optical probe and single mode fibers to transport light to and from the target. Using this unique approach, normal plate impact experiments are conducted on preheated (room temperature to near the melting point of magnesium) 99.9% polycrystalline magnesium using Inconel 718 target plates at impact velocities of 100–110 m/s. As inferred from the measured normal particle velocity history, the stress at the flyer/target interface shows progressive weakening with increasing sample temperatures below the melting point. At higher test temperatures, the rate of material softening under stress is observed to decrease and even reverse as the sample temperatures approach the melting point of magnesium samples. Scanning electron microscopy is utilized to understand the evolution of sample material microstructure including twinning following the impact event. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 806 KiB

Open AccessProceeding Paper

Experimental Model Validation and Fatigue Behaviour of Cold-Formed High Strength Steel

by S. Gothivarekar, S. Coppieters, R. H. Talemi and D. Debruyne

Proceedings 2018, 2(8), 373; https://doi.org/10.3390/ICEM18-05200 - 4 May 2018

Cited by 3 | Viewed by 1693

In the present paper, fatigue fracture behaviour of cold-formed High Strength Steel (HSS) S690QL are investigated. S690QL is often employed, in a pre-deformed state, for load-bearing applications, where cyclic service loads can be critical. Bending processes can induce residual plastic strain in bent [...] Read more.

In the present paper, fatigue fracture behaviour of cold-formed High Strength Steel (HSS) S690QL are investigated. S690QL is often employed, in a pre-deformed state, for load-bearing applications, where cyclic service loads can be critical. Bending processes can induce residual plastic strain in bent areas and this changes the fatigue behaviour significantly. Traditional uniaxial dogbone testing cannot represent this multi-axial phenomenon properly and for this purpose a benchmark specimen is proposed, that is first bent and after subjected to fatigue loading. The bending process is modelled with a quasi-static Finite Element (FE) model, performed in the commercial code Abaqus. To validate the numerical model, a stereo Digital Image Correlation (DIC) set-up is used, capable of measuring the residual plastic strains in the specimen. The present article covers the validation of a cold-forming process followed by a preliminary fatigue analysis of S690QL. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 841 KiB

Open AccessProceeding Paper

Characterization of the Modal Parameters of Composite Laminates Using Innovative Ultrathin Polymer Waveguide Sensor Foils

by Alfredo Lamberti, Wim Van Paepegem and Jeroen Missinne

Proceedings 2018, 2(8), 374; https://doi.org/10.3390/ICEM18-05195 - 4 May 2018

Viewed by 1444

The use of composite materials, like glass- and carbon- fiber reinforced polymers, is expected to increase exponentially in the coming years. Consequently, in order to monitor the structural health of these materials, the development of new sensing devices is rapidly accelerating. For this [...] Read more.

The use of composite materials, like glass- and carbon- fiber reinforced polymers, is expected to increase exponentially in the coming years. Consequently, in order to monitor the structural health of these materials, the development of new sensing devices is rapidly accelerating. For this purpose, our research groups have recently developed new ultra-thin polymer waveguide sensors which can be exploited to measure both uniaxial and multiaxial strains occurring in composite components. These sensing foils are manufactured by creating Bragg gratings in waveguides realized in flat polymeric substrates, which makes their placement and alignment easier compared to traditional fiber optic sensors. Moreover, using a non-straight waveguide it is possible to spatially multiplex the sensing gratings in such a way that an optical strain rosette can be created. This paper investigates the suitability of the proposed polymer waveguide sensors for the estimation of the modal parameters of composite components. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1407 KiB

Open AccessProceeding Paper

Experimental Characterization of Thermoplastics for Use in Heat Exchangers

by Joanna Schalnat, Anouar Krairi, Tom Wieme and Wim Van Paepegem

Proceedings 2018, 2(8), 375; https://doi.org/10.3390/ICEM18-05198 - 4 May 2018

Viewed by 1736

For the prediction of long term behavior several methods are known. This paper focuses on creep in dynamic mechanical analysis (DMA) and in a tensile setup. The investigated material was Polyamide 6 (PA6). As a pre-study for the DMA, Polypropylene (PP) was tested [...] Read more.

For the prediction of long term behavior several methods are known. This paper focuses on creep in dynamic mechanical analysis (DMA) and in a tensile setup. The investigated material was Polyamide 6 (PA6). As a pre-study for the DMA, Polypropylene (PP) was tested considering five different factors. To determine the significant influences, the results were interpreted statistically. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 365 KiB

Open AccessProceeding Paper

Constructing a Transparent Air Chamber for an Innovative Ventilation System in an Operating Room

by Victorien Desmars, Danny Van Hemelrijck and Valéry Ann Jacobs

Proceedings 2018, 2(8), 376; https://doi.org/10.3390/ICEM18-05199 - 4 May 2018

Viewed by 1543

While surgical techniques have been improving during last decades to the benefit of patients’ safety, infections are still recorded. It is in part due to airborne particles entering the wound during surgery, as a result of the disturbance of the unidirectional flow of [...] Read more.

While surgical techniques have been improving during last decades to the benefit of patients’ safety, infections are still recorded. It is in part due to airborne particles entering the wound during surgery, as a result of the disturbance of the unidirectional flow of clean air (LAF) by the presence of a surgical luminaire system. To prevent this negative interaction, an integrated system of light and ventilation has been designed. However, this system is still conceptual and a mechanical design is needed to prototype the system. Compliance with the European standard on surgical luminaires and the Heating, Ventilation and Air-Conditioning (HVAC) guidelines for operating rooms (OR) have to be checked for this prototype. We thus perform a structural analysis of the air chamber using Autodesk Inventor and SCIA Engineer considering different partitioning scenarios. The impact of each configuration is then assessed by considering the optical performance in the optical simulation TracePro. By comparing shifts in the results to a reference scenario an optimized configuration can be chosen. By consequence, a good balance between optical performance and mechanical strength is determined and leads to an optimized supporting solution. This mechanical design further enables us to build the integrated concept that aims to suppress the negative interaction between light and ventilation in the operating theater. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 860 KiB

Open AccessProceeding Paper

Long-Term In-Situ Study of Mild Steel Stress Corrosion Cracking Kinetics in a Carbonate-Rich Solution

by Roelf Mostert

Proceedings 2018, 2(8), 377; https://doi.org/10.3390/ICEM18-05197 - 9 May 2018

Cited by 1 | Viewed by 1785

A long-term SCC crack growth kinetics study, using precracked WOL samples, was performed. The samples were exposed in a mild steel storage tank containing a solution with high levels of ammonium and carbonate ions. Some samples were fully immersed in the tank content, [...] Read more.

A long-term SCC crack growth kinetics study, using precracked WOL samples, was performed. The samples were exposed in a mild steel storage tank containing a solution with high levels of ammonium and carbonate ions. Some samples were fully immersed in the tank content, while in other cases, intermittent drying took place in the tank upper regions. At short times, the highest (intergranular) crack growth rates were obtained at immersed regions and initially, the region with intermittent drying showed considerably slower growth rates. With pronounced exposure times, the trend however reversed and the growth in the intermittent drying region accelerated while the samples in the immersed location experienced a retardation in the SCC growth velocities. It was found that the SCC mechanism progressed through a process where small cracks first formed at the fatigue crack front and thereafter merged to form a continuous SCC crack front. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 435 KiB

Open AccessProceeding Paper

A Robust Test-Based Modal Model Identification Method for Challenging Industrial Cases

by El-Kafafy Mahmoud, Peeters Bart, Geluk Theo and Guillaume Patrick

Proceedings 2018, 2(8), 378; https://doi.org/10.3390/ICEM18-05196 - 4 May 2018

Viewed by 1736

Abstract: In this paper, the MLMM modal parameter estimation method (Maximum Likelihood estimation of a Modal Model) and its new variant will be introduced. The MLMM method tackles some of the remaining challenges in modal analysis (e.g., modal analysis of highly-damped cases [...] Read more.

Abstract: In this paper, the MLMM modal parameter estimation method (Maximum Likelihood estimation of a Modal Model) and its new variant will be introduced. The MLMM method tackles some of the remaining challenges in modal analysis (e.g., modal analysis of highly-damped cases where a large amount of excitation locations is needed such as the modal analysis of a trimmed car body). Another big advantage of the MLMM method is its capability to fully integrate, within the estimated modal model, some important physical constraints, which are required for the intended applications, e.g., realness of the mode shape and FRFs reciprocity. More classical modal parameter estimation methods have rarely the possibility to fully integrate these constraints and the obtained modal parameters are typically altered in a subsequent step to satisfy the desired constraints. It is obvious that this may lead to sub-optimal results. The MLMM method uses the Levenberg-Marquardt optimization scheme to directly fit the modal model to the measured FRFs. The applicability of MLMM to estimate an accurate constrained modal model will be demonstrated using two challenging industrial applications. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1421 KiB

Open AccessProceeding Paper

The Cause Estimation of Damages in Pathein Suspension Bridge Based on Vibration Measurements

by Osama Hegeir, Tsukasa Mizutani, Koji Matsumoto and Kohei Nagai

Proceedings 2018, 2(8), 379; https://doi.org/10.3390/ICEM18-05209 - 9 May 2018

Cited by 3 | Viewed by 2139

Pathein suspension bridge situated in Pathein City in the south of Myanmar has shown various symptoms of damage, and the safety of the bridge is questionable. The authorities concerned reported that the bridge has undergone severe deterioration since its construction, involving the towers’ [...] Read more.

Pathein suspension bridge situated in Pathein City in the south of Myanmar has shown various symptoms of damage, and the safety of the bridge is questionable. The authorities concerned reported that the bridge has undergone severe deterioration since its construction, involving the towers’ inclination, excessive deflections, bearing failure, heavy corrosion of main cables and hangers, hangers’ inclination, and slippage of clamps. The deformed shape of the stiffening girder was found to be unusual, with maximum deflection nearer to the towers; however, in a single span bridge, such as Pathein Bridge, the maximum deflection is expected to be at mid-span. This paper will explain the possible reasons for the unusual excessive deformations in the stiffening girder and bearing failure. The tension force of hangers was estimated based on vibration measurements, and the distribution of hangers’ tension force along the bridge’s span was found to be non-uniform with low-tension force in hangers closer to the towers. The non-uniform distribution of the hangers’ tension force is possibly due to shortcomings of the design of the cable system. The towers’ inclination has caused the road level to drop down; however, the unusual deformations in stiffening girder are attributed to the non-uniform distribution of the tension force in the hangers. Low-tension force in the hangers near the towers caused the bearing to carry excessive force, which eventually caused the bearing to fail; the bearing was rehabilitated by adding steel rollers. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1066 KiB

Open AccessProceeding Paper

Fatigue Damage Evaluation by Diffraction Contrast Tomography Using Ultra-Bright Synchrotron Radiation

by Yoshikazu Nakai, Daiki Shiozawa, Naoya Asakawa, Kenji Nonaka and Shoichi Kikuchi

Proceedings 2018, 2(8), 380; https://doi.org/10.3390/ICEM18-05210 - 9 May 2018

Viewed by 1736

A three-dimensional grain mapping technique for polycrystalline materials, called X-ray diffraction contrast tomography (DCT), was developed at SPring-8, which is the brightest synchrotron radiation facility in Japan. The developed technique was applied to an austenitic stainless steel. The shape and location of grains [...] Read more.

A three-dimensional grain mapping technique for polycrystalline materials, called X-ray diffraction contrast tomography (DCT), was developed at SPring-8, which is the brightest synchrotron radiation facility in Japan. The developed technique was applied to an austenitic stainless steel. The shape and location of grains could be determined by DCT using the apparatus in a beam line of SPring-8. To evaluate the dislocation structure in fatigue, the total misorientation of individual grains was measured by DCT. The average value of the total misorientation over one sample was increased with the number of cycles. In a grain, the change of the total misorientation was largest for the primary slip plane. The maximum change of the total misorientation in fatigue was larger for planes with larger Schmid factor, and the first fatigue crack initiation was occurred in a grain, which had the greatest change of the total misorientation. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1187 KiB

Open AccessProceeding Paper

An Improved Load Introduction Technique for Dynamic Material Characterisation at Intermediate Strain Rate

by Sanghyun Yoo, Dominik Schueler, Marcel Brodbeck, Nathalie Toso, Giuseppe Catalanotti and Heinz Voggenreiter

Proceedings 2018, 2(8), 381; https://doi.org/10.3390/ICEM18-05203 - 9 May 2018

Cited by 1 | Viewed by 2855

Dynamic properties at intermediate strain rate are inherently difficult due to the dynamic interactions between the test specimen and the test machine. These effects obscure the interpretation of test results and therefore can make the derivation of the material properties difficult and unprecise. [...] Read more.

Dynamic properties at intermediate strain rate are inherently difficult due to the dynamic interactions between the test specimen and the test machine. These effects obscure the interpretation of test results and therefore can make the derivation of the material properties difficult and unprecise. Soft materials can be used within load introduction devices to mitigate the inertia effect that typically occurs in dynamic tests. In this paper, dynamic tensile tests were performed within the strain rate range of 0.1 s⁻¹ to 400 s⁻¹ on high strength steels. With the aim of evaluating the performance of damping materials in the slack adaptor, copper and acrylic tapes were used. Experimental results show that both damping materials may be used to effectively reduce the oscillations in the measured force signal. The outcome of this project will provide the test procedure for dynamic testing at intermediate strain rates, which can produce reliable test results for materials with low failure to strain. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2173 KiB

Open AccessProceeding Paper

Inverse Yield Locus Identification of Sheet Metal Using a Complex Cruciform in Biaxial Tension and Digital Image Correlation

by Sam Coppieters, Tomoyuki Hakoyama, Dimitri Debruyne, Susumu Takahashi and Toshihiko Kuwabara

Proceedings 2018, 2(8), 382; https://doi.org/10.3390/ICEM18-05208 - 9 May 2018

Cited by 6 | Viewed by 1877

Finite Element Model Updating (FEMU) is an intuitive inverse technique enabling to efficiently characterize plastic material behavior. Although, conclusive proof of concept for this method can be found in literature, a thorough understanding of the key FEMU-ingredients and their impact on the identification [...] Read more.

Finite Element Model Updating (FEMU) is an intuitive inverse technique enabling to efficiently characterize plastic material behavior. Although, conclusive proof of concept for this method can be found in literature, a thorough understanding of the key FEMU-ingredients and their impact on the identification of plastic anisotropy is currently missing. In this paper, we aim at minimizing the experimental work associated with yield locus identification of sheet metal via homogeneous biaxial tensile tests. To this end, a biaxial tension apparatus with link mechanism is used to generate a heterogeneous deformation field within a perforated cruciform specimen. The experimentally measured force and displacement field are used in the FEMU procedure to identify an anisotropic yield criterion. The FEMU approach is assessed by comparing the results with experimental data acquired from state-of-the-art stress-controlled biaxial tensile test in the first quadrant of stress-space. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 2101 KiB

Open AccessProceeding Paper

Mechanical Characterization of Compact Basalt by Using SHPB Device

by Sunita Mishra, Tanusree Chakraborty and Vasant Matsagar

Proceedings 2018, 2(8), 383; https://doi.org/10.3390/ICEM18-05202 - 9 May 2018

Cited by 1 | Viewed by 2047

In the present work, dynamic stress-strain response of compact basalt is tested under high loading rates using 38 mm split Hopkinson pressure bar (SHPB) device. The physical and static mechanical properties of compact basalt, e.g., density, specific gravity, static compressive strength and elastic [...] Read more.

In the present work, dynamic stress-strain response of compact basalt is tested under high loading rates using 38 mm split Hopkinson pressure bar (SHPB) device. The physical and static mechanical properties of compact basalt, e.g., density, specific gravity, static compressive strength and elastic modulus values are also determined. Petrological studies of compact basalt are carried out through X-ray diffraction (XRD) test and scanning electron microscope (SEM) test. In the SHPB tests, it is observed from the stress-strain response that the dynamic peak stress increases with increasing strain rate however the elastic modulus is nearly constant with increase in strain rate. Dynamic force equilibrium at the incident and transmission bar ends of the rock samples is attained in all tests till the failure of the rock samples. Dynamic increase factor (DIF) for the rock is determined at a particular strain rate by comparing the dynamic to static peak compressive stress. Correlation equation for dynamic strength increase factor with respect to strain rate has been proposed herein. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1053 KiB

Open AccessProceeding Paper

Overview of Current Challenges in Self-Pierce Riveting of Lightweight Materials

by Mathias Jäckel, Thomas Grimm, Ronald Niegsch and Welf-Guntram Drossel

Proceedings 2018, 2(8), 384; https://doi.org/10.3390/ICEM18-05206 - 9 May 2018

Cited by 10 | Viewed by 2714

This paper shows an overview of different analyses regarding current challenges at self-pierce riveting with solid rivets as well as semi-tubular rivets of lightweight materials like aluminum die casting, carbon fiber reinforced plastic and 7xxx series aluminum alloy. The joining process analyses will [...] Read more.

This paper shows an overview of different analyses regarding current challenges at self-pierce riveting with solid rivets as well as semi-tubular rivets of lightweight materials like aluminum die casting, carbon fiber reinforced plastic and 7xxx series aluminum alloy. The joining process analyses will demonstrate the cause and the development as well as the influence on joint quality of individual joining process-induced defects. In addition, methods are described how these imperfections can be avoided or reduced. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 554 KiB

Open AccessProceeding Paper

Proposal to Standardize Fatigue Delamination Growth Tests Using Double Cantilever Beam Specimens without Fibre Bridging

by René Alderliesten

Proceedings 2018, 2(8), 385; https://doi.org/10.3390/ICEM18-05194 - 9 May 2018

Viewed by 1676

Up until today, mode-I fatigue delamination testing has not been standardized, because no consensus exists on best practices to reduce the observed scatter in data, and on the proper parameter describing similitude. A dominant contributor to the scatter seems the fibre bridging observed [...] Read more.

Up until today, mode-I fatigue delamination testing has not been standardized, because no consensus exists on best practices to reduce the observed scatter in data, and on the proper parameter describing similitude. A dominant contributor to the scatter seems the fibre bridging observed in the tests. This paper proposes a straightforward experimental and analysis approach to derive zero-bridging delamination resistance curves from each tested specimen without requiring a theoretical model. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 793 KiB

Open AccessProceeding Paper

Global Response of a Three-Story Building Exposed to Blast Loading

by Solveig Heggelund, Kristoffer Brekken, Petter Ingier and Svein Olav Christensen

Proceedings 2018, 2(8), 386; https://doi.org/10.3390/ICEM18-05211 - 9 May 2018

Cited by 4 | Viewed by 2053

Experimental data from full-scale experiments with reinforced concrete buildings exposed to blast loading are limited. As full-scale experiments are expensive, numerical simulations of the global response of structures exposed to blast loading may be an attractive substitute. A full-scale experiment on a three-story [...] Read more.

Experimental data from full-scale experiments with reinforced concrete buildings exposed to blast loading are limited. As full-scale experiments are expensive, numerical simulations of the global response of structures exposed to blast loading may be an attractive substitute. A full-scale experiment on a three-story reinforced concrete building exposed to air-blast is employed to evaluate the performance of FE simulations to represent global response of reinforced concrete structures. The building experienced close to elastic response in the load bearing walls and columns, while cracks were observed in the front wall facing the charge. FE simulations of the global response of the building are performed with a solid element model and a structural element model (shell elements) to compare accuracy to computational cost. The results show that the FE simulations with solid and structural elements give an adequate representation of the global response of the building to a relatively low cost. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 468 KiB

Open AccessProceeding Paper

Experimental and Numerical Investigation on the Impact Response of Elastomer-Coated Concrete

by Chanel Fallon and Graham McShane

Proceedings 2018, 2(8), 387; https://doi.org/10.3390/ICEM18-05212 - 9 May 2018

Cited by 2 | Viewed by 1810

The use of a spray application elastomer coating as an effective retrofit strategy for blast and impact mitigation has gained increasing attention in recent years. Despite some encouraging studies in the literature, there remains a great deal yet to be understood, particularly regarding [...] Read more.

The use of a spray application elastomer coating as an effective retrofit strategy for blast and impact mitigation has gained increasing attention in recent years. Despite some encouraging studies in the literature, there remains a great deal yet to be understood, particularly regarding the coating’s impact mitigating capabilities when applied to structural elements. In this work, we consider the application of a spray-on elastomer coating to the impacted face of a concrete cube. High-speed, gas gun experiments are performed on concrete cubes in their uncoated and coated configurations and it is observed that the coating provides a significant protective benefit across the range of test velocities, 45–150 m/s. Quasi-static compression and indentation experimental tests are performed on uncoated and coated concrete cubes to inform the development of a numerical model. Despite a number of modelling challenges, we validate our model against experimental measurements and conclude it provides accurate predictions of behaviour at early time steps, before the concrete becomes severely damaged. Future work will focus on using this validated numerical model as an analysis tool for understanding the mechanism by which the elastomer alters the damage response of the underlying concrete substrate. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1042 KiB

Open AccessProceeding Paper

3D Modeling of Plaque Progression in the Human Coronary Artery

by Igor Saveljic, Dalibor Nikolic, Zarko Milosevic, Velibor Isailovic, Milica Nikolic, Oberdan Parodi and Nenad Filipovic

Proceedings 2018, 2(8), 388; https://doi.org/10.3390/ICEM18-05213 - 9 May 2018

Cited by 3 | Viewed by 2197

The inflammation and lipid accumulation in the arterial wall represents a progressive disease known as atherosclerosis. In this study, a numerical model of atherosclerosis progression was developed. The wall shear stress (WSS) and blood analysis data have a big influence on the development [...] Read more.

The inflammation and lipid accumulation in the arterial wall represents a progressive disease known as atherosclerosis. In this study, a numerical model of atherosclerosis progression was developed. The wall shear stress (WSS) and blood analysis data have a big influence on the development of this disease. The real geometry of patients, and the blood analysis data (cholesterol, HDL, LDL, and triglycerides), used in this paper, was obtained within the H2020 SMARTool project. Fluid domain (blood) was modeled using Navier-Stokes equations in conjunction with continuity equation, while the solid domain (arterial wall) was modeled using Darcy’s law. For the purpose of modeling low-density lipoprotein (LDL) and oxygen transport, convection-diffusion equations were used. Kedem-Katchalsky equations were used for coupling fluid and solid dynamics. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 847 KiB

Open AccessProceeding Paper

Crack Tip Monitoring of Mode I and Mode II Delamination in CF/Epoxies under Static and Dynamic Loading Conditions Using Digital Image Correlation

by Brendan R. Murray, Sander Fonteyn, Delphine Carrella-Payan, Kalliopi-Artemi Kalteremidou, Anghel Cernescu, Danny Van Hemelrijck and Lincy Pyl

Proceedings 2018, 2(8), 389; https://doi.org/10.3390/ICEM18-05225 - 9 May 2018

Cited by 3 | Viewed by 2008

Digital image correlation has been used, in conjunction with Mode I and Mode II fracture mechanics tests under static and dynamic loading conditions, to determine the position of the crack front during interlaminar testing. A MATLAB code has been developed to post process [...] Read more.

Digital image correlation has been used, in conjunction with Mode I and Mode II fracture mechanics tests under static and dynamic loading conditions, to determine the position of the crack front during interlaminar testing. A MATLAB code has been developed to post process the digital image correlation analysis to determine the experimentally measured crack position and these results have been compared to compliance-based predictions of crack position which do not use a physical measure of the crack length. Results have shown that the digital image correlation analysis has successfully tracked the crack position providing a physical measure of the crack front during static and dynamic testing for the calculation of fracture toughness values. This methodology, incorporating digital image correlation for crack position monitoring, was then expanded to analyses for fatigue tests showing that the physical crack length has a varied growth rate in comparison to the steady change in specimen compliance. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1693 KiB

Open AccessProceeding Paper

Lab-on-Chip Prototype for the Detection of Coronary Artery Disease Biomarkers

by Aliki Tsopela, Sandro Meucci, Silvia Rocchiccioli, Gualtiero Pelosi and Monica Brivio

Proceedings 2018, 2(8), 390; https://doi.org/10.3390/ICEM18-05215 - 9 May 2018

Viewed by 1884

We report an easy-to-use Lab-on-Chip (LoC) device able to detect soluble, circulating biomarkers in plasma that are relevant to Coronary Artery Disease (CAD). The LoC prototype is developed within the SMARTool European project and is intended to be used for Point-of-Care (PoC) testing [...] Read more.

We report an easy-to-use Lab-on-Chip (LoC) device able to detect soluble, circulating biomarkers in plasma that are relevant to Coronary Artery Disease (CAD). The LoC prototype is developed within the SMARTool European project and is intended to be used for Point-of-Care (PoC) testing of patients with CAD, facilitating more rapid and efficient monitoring and treatment decisions. A LoC prototype is presented, enabling chemiluminescent assays to be performed on chip targeting biomarkers relevant to CAD. In parallel, a robust technology for electrostatically actuated, capillary burst valve for PoC applications, integrated in potentially disposable, thermoplastic devices is reported. The devices were fabricated using easily scalable fabrication techniques and can be used to perform multistep assays on single-use microfluidic devices. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 878 KiB

Open AccessProceeding Paper

Steps towards Industrial Validation Experiments

by Erwin Hack, Richard Burguete, Ksenija Dvurecenska, George Lampeas, Eann Patterson, Thorsten Siebert and Eszter Szigeti

Proceedings 2018, 2(8), 391; https://doi.org/10.3390/ICEM18-05216 - 9 May 2018

Cited by 1 | Viewed by 2355

Imaging systems for measuring surface displacement and strain fields such as stereoscopic Digital Image Correlation (DIC) are increasingly used in industry to validate model simulations. Recently, CEN has published a guideline for validation that is based on image decomposition to compare predicted and [...] Read more.

Imaging systems for measuring surface displacement and strain fields such as stereoscopic Digital Image Correlation (DIC) are increasingly used in industry to validate model simulations. Recently, CEN has published a guideline for validation that is based on image decomposition to compare predicted and measured data fields. The CEN guideline was evaluated in an inter-laboratory study that demonstrated its usefulness in laboratory environments. This paper addresses the incorporation of the CEN methodology into an industrial environment and reports progress of the H2020 Clean Sky 2 project MOTIVATE. First, while DIC is a well-established technique, the estimation of its measurement uncertainty in an industrial environment is still being discussed, as the current approach to rely on the calibration uncertainty is insufficient. Second, in view of the push towards virtual testing it is important to harvest existing data in the course of the V&V activities before requesting a dedicated validation experiment, specifically at higher levels of the test pyramid. Finally, it is of uttermost importance to ensure compatibility and comparability of the simulation and measurement data so as to optimize the test matrix for maximum reliability and credibility of the simulations and a quantification of the model quality. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1962 KiB

Open AccessProceeding Paper

Static and Fatigue Damage Characterization of Carbon/Epoxy Angle-Ply Laminates with the Use of Acoustic Emission and Online Microscopy

by Kalliopi-Artemi Kalteremidou, Eleni Tsangouri, Anghel Cernescu, Brendan R. Murray, Lincy Pyl, Dimitrios G. Aggelis and Danny Van Hemelrijck

Proceedings 2018, 2(8), 392; https://doi.org/10.3390/ICEM18-05220 - 14 May 2018

Viewed by 1487

In the current work, a combined non-destructive methodology is proposed in order to investigate the static and fatigue damage of carbon fiber reinforced epoxy composites. Flat angle-ply laminates are used in order to examine the influence of multiaxial stress states on the mechanical [...] Read more.

In the current work, a combined non-destructive methodology is proposed in order to investigate the static and fatigue damage of carbon fiber reinforced epoxy composites. Flat angle-ply laminates are used in order to examine the influence of multiaxial stress states on the mechanical performance using different non-destructive techniques. Acoustic emission is combined with an online microscope and digital image correlation and this combination is used to comprehend the performance of composites with unequal stress states. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 680 KiB

Open AccessProceeding Paper

Analysis of the Flexural Behavior of Textile Reinforced Reactive Powder Concrete Sandwich Elements Using Optical Measurements

by Natalie Williams Portal, Mathias Flansbjer and Urs Mueller

Proceedings 2018, 2(8), 393; https://doi.org/10.3390/ICEM18-05221 - 14 May 2018

Cited by 1 | Viewed by 1649

Prefabricated and non-load bearing sandwich façade elements were developed using Textile Reinforced Reactive Powder Concrete (TRRPC) along with low density Foamed Concrete (FC) and Glass Fiber Reinforced Polymer (GFRP) continuous connecting devices. Four-point bending tests were performed on large-scale TRRPC sandwich element beams [...] Read more.

Prefabricated and non-load bearing sandwich façade elements were developed using Textile Reinforced Reactive Powder Concrete (TRRPC) along with low density Foamed Concrete (FC) and Glass Fiber Reinforced Polymer (GFRP) continuous connecting devices. Four-point bending tests were performed on large-scale TRRPC sandwich element beams to characterize the structural performance, which included the flexural capacity, level of composite action, resulting deformation, crack propagation and failure mechanisms. Optical measurements based on Digital Image Correlation (DIC) were taken simultaneously to enable a detailed analysis of the underlying composite action. The structural behavior of the developed elements was found to be highly dependent on the stiffness and strength of the connectors to ensure composite action between the two TRRPC panels. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1663 KiB

Open AccessProceeding Paper

Acoustic Emission Signal Associated to Fiber Break during a Single Fiber Fragmentation Test: Modeling and Experiment

by Zeina Hamam, Nathalie Godin, Claudio Fusco and Thomas Monnier

Proceedings 2018, 2(8), 394; https://doi.org/10.3390/ICEM18-05222 - 14 May 2018

Cited by 1 | Viewed by 1518

The objective of this work is to build a quantitative relationship between the fiber break as source of Acoustic Emission (AE) and the detected signal by unravelling the effect of each stage of the AE acquisition chain. For this purpose, an AE modelling [...] Read more.

The objective of this work is to build a quantitative relationship between the fiber break as source of Acoustic Emission (AE) and the detected signal by unravelling the effect of each stage of the AE acquisition chain. For this purpose, an AE modelling is carried out using the Finite Element Method and then the simulation is compared to experimental results of Single Fiber Fragmentation Test (SFFT). The SFFT is used in order to produce preferential fiber break. It is carried out on specimens made from a long carbon fiber embedded in epoxy/amine matrix. Two different types of sensor are used in order to gather information on a wider frequency bandwidth. For the modeling part, the entire geometry of the specimen is modelled using Finite Element Method. There is a good agreement between experiment and modeling results. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 663 KiB

Open AccessProceeding Paper

Characterization Procedure for Bond, Anchorage and Strain-Hardening Behavior of Textile-Reinforced Cementitious Composites

by Jan Bielak, Yingxiong Li, Josef Hegger and Rostislav Chudoba

Proceedings 2018, 2(8), 395; https://doi.org/10.3390/ICEM18-05224 - 15 May 2018

Cited by 3 | Viewed by 1897

A fast adoption of innovative composite materials such as textile reinforced concrete (TRC) in practice is hindered by the lack of efficient and standardized characterization and design procedures. In this paper, we discuss results of uniaxial tensile tests and double sided pullout tests. [...] Read more.

A fast adoption of innovative composite materials such as textile reinforced concrete (TRC) in practice is hindered by the lack of efficient and standardized characterization and design procedures. In this paper, we discuss results of uniaxial tensile tests and double sided pullout tests. The analysis of the tests is done with a modelling framework for tensile behavior developed at IMB RWTH Aachen. The overall goal is to simulate the tensile response of composite specimen based on the reinforcement and matrix characteristics. Thus, the need for cost-intensive composite tensile tests could be reduced, which facilitates the material development and adoption of TRC in engineering practice. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 929 KiB

Open AccessProceeding Paper

Experimental Analysis of Monotonic and Cyclic Pull-Out of Steel Fibres by Means of Acoustic Emission and X-ray Microfocus Computed Tomography

by Maure De Smedt, Kristof De Wilder, Els Verstrynge and Lucie Vandewalle

Proceedings 2018, 2(8), 396; https://doi.org/10.3390/ICEM18-05226 - 15 May 2018

Viewed by 1901

This research aims to investigate the monotonic and cyclic pull-out behavior of steel fibres by means of advanced non-destructive testing methods (NDT). Forty individually embedded steel fibres in a concrete matrix are tested in a pull-out setup with continuous acoustic emission monitoring and [...] Read more.

This research aims to investigate the monotonic and cyclic pull-out behavior of steel fibres by means of advanced non-destructive testing methods (NDT). Forty individually embedded steel fibres in a concrete matrix are tested in a pull-out setup with continuous acoustic emission monitoring and X-ray microfocus computed tomography is applied before, during and after testing. The developed setup allows to improve and to better control the experiments. The combination of NDT methods leads to a deeper insight compared to the traditional pull-out tests, by inspection of deviating results, detection of the pull-out stages, and localization of internal damage combined with visualization of the internal structure. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2932 KiB

Open AccessProceeding Paper

Investigation of 3D TRC’s by Means of Three Point Bending Tests on Short Beam Specimens

by Michael El Kadi, Svetlana Verbruggen, Jolien Vervloet, Matthias De Munck, Jan Wastiels, Danny Van Hemelrijck and Tine Tysmans

Proceedings 2018, 2(8), 397; https://doi.org/10.3390/ICEM18-05227 - 15 May 2018

Viewed by 1599

Textile reinforced cements (TRC), combining a cementitious matrix with fibre textiles, are a well-researched subject in literature. The material offers several advantages such as the design of low-weight, slender structures. However, one of the main drawbacks of this composite material is the time [...] Read more.

Textile reinforced cements (TRC), combining a cementitious matrix with fibre textiles, are a well-researched subject in literature. The material offers several advantages such as the design of low-weight, slender structures. However, one of the main drawbacks of this composite material is the time consuming manufacturing process using two dimensional fibre textiles. Three dimensional fibre textile architectures offer a solution to this problem, while retaining the TRC advantages. Most 3D fibre textiles use distance holders to bridge two, or more textile layers at a certain distance from each other. The influence of this distance holder on the mechanical properties of the whole TRC remains relatively unstudied in literature and will be the research topic of this paper. This research will present the results of three point bending experiments, performed on short TRC beams with a length to thickness ratio of approximately 4 to 1. A comparison is drawn between 3D TRC with fully operational 3D fibre textiles and 2D TRC with the same textile geometry and orientation, but without distance holders. A positive influence on the flexural response is witnessed for the 3D fibre textile, with an increased flexural stiffness up to 35%. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 508 KiB

Open AccessProceeding Paper

Ultrahigh Carbon Nanotube Volume Fraction Effects on Micromechanical Quasi-Static & Dynamic Properties of Poly(Urethane-Urea) Filled Nanocomposites

by Jeffrey L. Gair, Jr., Dale L. Lidston, Daniel P. Cole, Robert H. Lambeth, Alex J. Hsieh, Hugh A. Bruck, Asha J. Hall, Mark L. Bundy and Brian L. Wardle

Proceedings 2018, 2(8), 398; https://doi.org/10.3390/ICEM18-05228 - 15 May 2018

Viewed by 1645

Poly(urethane-urea) (PUU) has been infused into ultrahigh volume fraction carbon nanotube (CNT) forests using a heat-curable polymer formula. Polymer nanocomposites with carbon nanotube volume-fractions of 1%, 5%, 10%, 20%, and 30% were fabricated by overcoming densification and infusion obstacles. These polymer nanocomposites were [...] Read more.

Poly(urethane-urea) (PUU) has been infused into ultrahigh volume fraction carbon nanotube (CNT) forests using a heat-curable polymer formula. Polymer nanocomposites with carbon nanotube volume-fractions of 1%, 5%, 10%, 20%, and 30% were fabricated by overcoming densification and infusion obstacles. These polymer nanocomposites were nanoindented quasi-statically and dynamically to discern process-structure-(mechanical) property relations of polymerizing PUU in such densely-packed CNT forests. A 100× increase in indentation modulus has been observed, which is attributed not only to CNT reinforcement of the matrix, but also to molecular interactions in the matrix itself. Quasi-static elastic moduli ranging from 10 MPa–4.5 GPa have been recorded. Storage modulus for all materials is found to track well at loadings of 200 Hz, with little effect observed from increasing CNT volume fraction. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 609 KiB

Open AccessProceeding Paper

Comparison of Fracture Resistance of the Normal and High Strength Concrete Evaluated by Brazilian Disc Test

by Petr Miarka, Stanislav Seitl and Vlastimil Bílek

Proceedings 2018, 2(8), 399; https://doi.org/10.3390/ICEM18-05236 - 19 May 2018

Cited by 4 | Viewed by 1791

Nowadays, high performance concrete is used more frequently because of the many advantages compared to traditional concrete. The higher mechanical properties (e.g., compressive strength, flexural strength, and Young’s modulus) allow for larger spans and slender cross-sections. Despite the use of advanced material, standards [...] Read more.

Nowadays, high performance concrete is used more frequently because of the many advantages compared to traditional concrete. The higher mechanical properties (e.g., compressive strength, flexural strength, and Young’s modulus) allow for larger spans and slender cross-sections. Despite the use of advanced material, standards for structural design do not fully use materials’ potential. This can be minimized by using fracture mechanical properties in structural analysis. The fracture mechanical properties help to perform advanced structural analysis, especially when some of the structural elements have a crack. The load presence on the structure can be divided into tensile—mode I, shear—mode II, and combination of tension and shear—mixed mode I/II load. Therefore, it is necessary to perform test, which covers mixed mode loading conditions. One of the tests usually used for the evaluation of fracture resistance of concrete is Brazilian disc test. This contribution compares fracture resistance of two types of structural concrete (normal and high strength) under the mixed mode I/II. The generalized maximum tangential stress (GMTS) criterion was used for the evaluation of the fracture resistance. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1028 KiB

Open AccessProceeding Paper

On the Material Characterization of an Aluminium Alloy Using Different Specimens and Identification Methods

by Susanne Thomesen, Odd Sture Hopperstad and Tore Børvik

Proceedings 2018, 2(8), 400; https://doi.org/10.3390/ICEM18-05237 - 19 May 2018

Cited by 3 | Viewed by 2026

The validity of material properties obtained from uniaxial tension tests using different specimen types and measurement techniques is investigated in this paper. Four different specimen geometries were tested, including round axisymmetric and rectangular flat samples of different sizes. This gave a significant variation [...] Read more.

The validity of material properties obtained from uniaxial tension tests using different specimen types and measurement techniques is investigated in this paper. Four different specimen geometries were tested, including round axisymmetric and rectangular flat samples of different sizes. This gave a significant variation in both size and shape of the specimens. The specimens were strained in tension to fracture, and different measurement techniques were applied to measure the deformation of the specimens during loading. This involved an extensometer, a laser micrometre, digital image correlation (DIC) and edge tracing. Cauchy stress versus logarithmic strain curves were obtained from the experimental data, and little spread was seen between the different test series. The data were further used to calibrate a work-hardening relation for the material, and it was found that the fitted curves differed mainly for strains beyond diffuse necking. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1253 KiB

Open AccessProceeding Paper

Analysis of Failure Modes in Fiber Reinforced Concrete Using X-ray Tomography and Digital Volume Correlation

by Mathias Flansbjer, Natalie Williams Portal, Stephen Hall and Jonas Engqvist

Proceedings 2018, 2(8), 401; https://doi.org/10.3390/ICEM18-05238 - 19 May 2018

Cited by 3 | Viewed by 1920

Pull-out mechanisms for different common steel fibers were investigated using adapted pull-out tests performed in-situ in an X-ray micro tomograph (µXRT). High-resolution volume images from the µXRT scans enable clear visualization of aggregates, pores, the fiber and the fiber-matrix interface. Furthermore, the natural [...] Read more.

Pull-out mechanisms for different common steel fibers were investigated using adapted pull-out tests performed in-situ in an X-ray micro tomograph (µXRT). High-resolution volume images from the µXRT scans enable clear visualization of aggregates, pores, the fiber and the fiber-matrix interface. Furthermore, the natural density speckle pattern from aggregate distribution and pores was found suitable for Digital Volume Correlation (DVC) analysis. From the DVC results it was possible to visualize and quantify the strain distribution in the matrix around the fiber at the different load levels up to final failure, being marked by either pull-out or fiber rupture. This study demonstrates that strain measurements within the concrete matrix can be obtained successfully using µXRT imaging and DVC analysis, which leads to an increased understanding of the interaction mechanisms in fibre reinforced concrete under mechanical loading. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 459 KiB

Open AccessProceeding Paper

Crack Resistance of RT-PMMA under Impact Loading

by Norazrina Mat Jali and Patrice Longère

Proceedings 2018, 2(8), 402; https://doi.org/10.3390/ICEM18-05239 - 19 May 2018

Cited by 1 | Viewed by 2149

Analysis of failure mechanisms under high strain rate loading in engineering materials is a key point for the design of structures submitted to accidental overloads. We are here interested in the crack arrest capability under impact loading of polymers used as structural and/or [...] Read more.

Analysis of failure mechanisms under high strain rate loading in engineering materials is a key point for the design of structures submitted to accidental overloads. We are here interested in the crack arrest capability under impact loading of polymers used as structural and/or protection materials. In the present work, crack arrest capability is defined by how an engineering structure which is initially weakened by a pre-crack behaves when dynamically reloaded. The Kalthoff and Winkler (KW) impact test, consisting in impacting the edge of a double notched plate, is retained for that purpose. An experimental investigation of the dynamic crack arrest capability of shock-resistant PMMA under high strain rate loading is presented, evidencing the brittle feature of the material failure. A high-speed camera is used to record the chronology of the failure mechanisms. It is notably shown that the higher the impact velocity (in the range 50–100 m/s) the larger the number of fragments. Moreover, depending on the impact velocity, changes in the crack path and thus in the mechanisms controlling the PMMA dynamic fracture can be seen. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 659 KiB

Open AccessProceeding Paper

Experimental Study on Spallation of Titanium Alloy Plates under Intense Impulse Loading

by Yayun Zhao, Ruiyu Li, Jianjun Mo, Fuli Tan and Yuxin Sun

Proceedings 2018, 2(8), 403; https://doi.org/10.3390/ICEM18-05240 - 20 May 2018

Cited by 1 | Viewed by 1680

The dynamic response and spall characteristics of a double-layer TC4 titanium alloy thin target under intense impulse loading was investigated experimentally using electric gun technique. A velocity-measuring instrument, known as VISAR (velocity interferometer system for any reflector), measured the free surface velocity of [...] Read more.

The dynamic response and spall characteristics of a double-layer TC4 titanium alloy thin target under intense impulse loading was investigated experimentally using electric gun technique. A velocity-measuring instrument, known as VISAR (velocity interferometer system for any reflector), measured the free surface velocity of targets. Typical characteristic parameters of the velocity were calculated by the obtained data. The deformation/failure modes of the samples were analyzed, and based on stress wave propagation theory, the spall thickness was derived. Furthermore, it was found that the oscillation period of the free surface velocity can be used to estimate the location of spalling damage, but cannot directly reflect the full spallation of the target. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 803 KiB

Open AccessProceeding Paper

Research on the Artificial Acceleration Test System of Combined Environment and Loading Effect for the Bridge Structure

by Guowen Yao, Xicheng Tan, Shiya Li, Peiyan Huang and Jiayu Yu

Proceedings 2018, 2(8), 404; https://doi.org/10.3390/ICEM18-05282 - 29 May 2018

Cited by 1 | Viewed by 1870

The bridges will be in service in a complex environment for over 100 years under the increasing traffic loading. So the long-term performance determines their safety and durability. Limited by the test condition and ability, present researches are mostly focused on the natural [...] Read more.

The bridges will be in service in a complex environment for over 100 years under the increasing traffic loading. So the long-term performance determines their safety and durability. Limited by the test condition and ability, present researches are mostly focused on the natural environment exposure tests and artificial environment acceleration tests for materials and components. According to the service conditions and load characteristics of the bridges, the accelerated test system was developed for bridge structure under combined environment and loading. This test system consists of three parts, including a large environment box, loading system and monitoring system. The environment box is 32 m long, 4 m wide and 3/10 m high. It is divided into 5 working bins which can be used alone or in combination. The simulation environment includes high temperature drying, low temperature freezing and thawing, damp cold, high temperature cycle, salt fog, rain, carbonation, temperature and humidity alternating and optical spectrum light aging environment. The servo static and dynamic loading system adopts Servotest actuators with loading tonnage from 400 tons to 50 tons. And the total tonnage is 1200 tons. Aided by the prestressed concrete reaction wall, steel structure frames and the anchor system, the external loading system can exert dynamic and static loads on the bridge structure in the environment box. And the non-contact nondestructive monitoring system can real-time monitor and measure their long-term deformation, internal force, cracking and other damage. This artificial acceleration test system can support the Chinese Long Term Bridge Program, and improve the safety, durability, reliability and long service life of bridges and other civil engineering. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 667 KiB

Open AccessProceeding Paper

Dynamic Tensile Testing of Brittle Composites Using a Hydraulic Pulse Machine: Stress-Strain Synchronization and Strain Rate Limits

by Siebe W. F. Spronk, Erik Verboven, Francisco A. Gilabert, Ruben D. B. Sevenois, David Garoz, Mathias Kersemans and Wim Van Paepegem

Proceedings 2018, 2(8), 405; https://doi.org/10.3390/ICEM18-05274 - 27 May 2018

Cited by 2 | Viewed by 1990

The effect of synchronization on the test results is explored by performing dynamic tensile tests on several continuous-fibre composite laminates. The results show that synchronization is key, because a delay of a single microsecond significantly affects the test outcome at high strain rates. [...] Read more.

The effect of synchronization on the test results is explored by performing dynamic tensile tests on several continuous-fibre composite laminates. The results show that synchronization is key, because a delay of a single microsecond significantly affects the test outcome at high strain rates. Additionally, several upper limits on the maximum achievable strain rate of the experimental set-up are determined with the aid of a finite element model. These limits depend on the characteristics of the used equipment, the properties of the tested material and the chosen specimen dimensions. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 732 KiB

Open AccessProceeding Paper

Investigation to Local Defect Resonance for Non-Destructive Testing of Composites

by Joost Segers, Mathias Kersemans, Erik Verboven, Saeid Hedayatrasa, Javier Calderon and Wim Van Paepegem

Proceedings 2018, 2(8), 406; https://doi.org/10.3390/ICEM18-05273 - 27 May 2018

Cited by 7 | Viewed by 1903

Local defect resonance (LDR) makes use of high frequency vibrations to get a localized resonant activation of a defective region. In this study, the LDR behavior of carbon fiber reinforced polymer (CFRP) coupons with three different types of damages is investigated using broadband [...] Read more.

Local defect resonance (LDR) makes use of high frequency vibrations to get a localized resonant activation of a defective region. In this study, the LDR behavior of carbon fiber reinforced polymer (CFRP) coupons with three different types of damages is investigated using broadband measurements obtained with a scanning laser Doppler vibrometer (SLDV). First, the LDR response of flat bottom holes of different depths and sizes is evaluated using a signal-to-noise ratio. Next, results are obtained for ETFE inserts where the difference between (artificial) delaminations and inserts is outlined. At last, the vibrational response of a CFRP coupon with barely visible impact damage is investigated. This type of damage has a more complex structure, and it is shown that frequency band data (an alternative to the single frequency LDR) performs well in identifying such complex damage. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 937 KiB

Open AccessProceeding Paper

Inverse Analysis for Estimating Temperature and Residual Stress Distributions in a Pipe from Outer Surface Temperature Measurement and Its Regularization

by Shiro Kubo and Shoki Taguwa

Proceedings 2018, 2(8), 407; https://doi.org/10.3390/ICEM18-05284 - 30 May 2018

Viewed by 1421

This paper presents an inverse analysis method for estimating the temperature and thermal residual stress distributions in the pipe from the temperature history measured on the outer surface. A regularization method was introduced. It is found from numerical simulations that the proposed inverse [...] Read more.

This paper presents an inverse analysis method for estimating the temperature and thermal residual stress distributions in the pipe from the temperature history measured on the outer surface. A regularization method was introduced. It is found from numerical simulations that the proposed inverse analysis method with regularization is useful for obtaining a reasonable estimate of the inner surface temperature and thermal stress. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2463 KiB

Open AccessProceeding Paper

Novel Experimental Design for Two-Dimensional Delamination in Fiber-Reinforced Polymer Laminates

by Aida Cameselle-Molares, Anastasios P. Vassilopoulos and Thomas Keller

Proceedings 2018, 2(8), 408; https://doi.org/10.3390/ICEM18-05283 - 30 May 2018

Viewed by 1497

The two-dimensional (2D) delamination behavior of composite laminates under quasi-static out-of-plane opening loads has been experimentally investigated. A novel design and experimental set-up for fiber-reinforced polymer (FRP) laminated plates with a circular embedded pre-crack was developed. Increasing load-displacement curves were obtained due to [...] Read more.

The two-dimensional (2D) delamination behavior of composite laminates under quasi-static out-of-plane opening loads has been experimentally investigated. A novel design and experimental set-up for fiber-reinforced polymer (FRP) laminated plates with a circular embedded pre-crack was developed. Increasing load-displacement curves were obtained due to the increasing crack front length during propagation. Throughout the loading process, stiffening and softening mechanisms were activated. The stretching of delaminated part of the laminates constituted the main stiffening mechanism. Once the crack started growing, a corresponding softening due to crack propagation occurred together with a secondary stiffening mechanism, fiber-bridging. These stiffness-related mechanisms were reflected in the compliance. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1268 KiB

Open AccessProceeding Paper

Effect of the Nitrogen Diffusion Layer Formed by Gas Blow Induction Heating Nitriding on Wear Resistance and Fatigue Properties of Titanium Alloy

by Shogo Takesue, Shoichi Kikuchi, Hiroyuki Akebono and Jun Komotori

Proceedings 2018, 2(8), 409; https://doi.org/10.3390/ICEM18-05285 - 30 May 2018

Cited by 2 | Viewed by 1751

The effect of the nitrogen diffusion layer formed by gas blow induction heating nitriding on the wear resistance and the fatigue properties of a titanium alloy was investigated. The nitrogen diffusion layer deteriorated the wear resistance of a titanium alloy. This is probably [...] Read more.

The effect of the nitrogen diffusion layer formed by gas blow induction heating nitriding on the wear resistance and the fatigue properties of a titanium alloy was investigated. The nitrogen diffusion layer deteriorated the wear resistance of a titanium alloy. This is probably because hard abrasive particles worn from the diffusion layer accelerates the wear of the material. In contrast, the diffusion layer improved the fatigue properties of a titanium alloy. This is due to the high hardness of the diffusion layer, and because the layer and the substrate share the same elastic modulus, the surface stress concentration is inhibited. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1387 KiB

Open AccessProceeding Paper

Finite Element Modelling of Cardiac Ischemia and Data Mining Application for Ischemic Detection and Localization

by Đorović Smiljana, Robnik-Šikonja Marko, Radović Miloš, Anđelković Ćirković Bojana and Filipović Nenad

Proceedings 2018, 2(8), 410; https://doi.org/10.3390/ICEM18-05269 - 24 May 2018

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The main aim of this paper was to computationally simulate the cardiac ischemia employing Finite Element Method (FEM) and detect its presence and localization using data mining approach. A simplified heart-torso model was created based on computed tomography (CT) images, with performed segmentation [...] Read more.

The main aim of this paper was to computationally simulate the cardiac ischemia employing Finite Element Method (FEM) and detect its presence and localization using data mining approach. A simplified heart-torso model was created based on computed tomography (CT) images, with performed segmentation of the heart (17 zones). Ischemic and non-ischemic cardiac beats were simulated in different zones with aim to create a virtual database which was used for data mining. Using the virtual database, we trained several classifiers and tested them for the purpose of ischemic beat detection based on the body surface potentials map (BSPM). If the ECG is classified as ischemic by the first stage classifier, potentials were processed by the second stage data mining model, which predicted the location of the ischemic area. The use of the second stage classifier, which located the ischemia in one of the heart’s segments created in the FEM model, goes beyond the current state of the art. Thus, the proposed approach is improved solution which can instantly allow clinicians to implement an adequate treatment strategy in future. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 702 KiB

Open AccessProceeding Paper

Investigations of Cruciform Specimen Designs for Biaxial Tensile Testing of SMC

by Juliane Lang, Malte Schemmann, Thomas Seelig and Thomas Böhlke

Proceedings 2018, 2(8), 411; https://doi.org/10.3390/ICEM18-05279 - 31 May 2018

Cited by 1 | Viewed by 2552

This proceedings paper presents the investigation of different cruciform specimen designs for the characterization of Sheet Molding Compounds under biaxial loading. Biaxial tensile tests allow the investigation of damage evolution under multiaxial stress states, which is particularly interesting due to the different damage [...] Read more.

This proceedings paper presents the investigation of different cruciform specimen designs for the characterization of Sheet Molding Compounds under biaxial loading. Biaxial tensile tests allow the investigation of damage evolution under multiaxial stress states, which is particularly interesting due to the different damage phenomena in composite materials. A key challenge is to find a suitable specimen shape, because typical cruciform specimens fail in the arms before damage occurs in the area of interest which is the area of the biaxial stress state in the center region of the specimen. For all of the introduced designs the stiffness degradation is analyzed more in detail and compared to that of a uniaxial bone specimen. For the best performing specimen which is reinforced by unidirectional reinforced tapes on the arms, the strain field is analyzed by finite element simulations, taking into account the mechanical properties of the different layers of the specimen. Especially in the center area and at critical points, strain concentrations and non-symmetrical strain distributions are analyzed and evaluated. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 653 KiB

Open AccessProceeding Paper

Rigid–Flexible Contact Analysis of an Inflated Membrane Balloon with Various Contact Conditions

by MengXiong Liu and XiDe Li

Proceedings 2018, 2(8), 412; https://doi.org/10.3390/ICEM18-05264 - 24 May 2018

Viewed by 1994

Considering the Mooney–Rivlin hyperelastic model, a semi-analytical approach is introduced to analyze the rigid–flexible contact behavior of an inflated membrane balloon between two plates with various interface conditions. This approach is based on differential formulation, and the coupling properties of equilibrium equations are [...] Read more.

Considering the Mooney–Rivlin hyperelastic model, a semi-analytical approach is introduced to analyze the rigid–flexible contact behavior of an inflated membrane balloon between two plates with various interface conditions. This approach is based on differential formulation, and the coupling properties of equilibrium equations are well-solved. In order to verify the reliability of the proposed theoretical model, an experimental test was designed, by which some important contact characteristics and patterns (no-slip condition) were obtained. Two special phenomena were observed for the meridian stretch ratio with different friction coefficients. One is that the intersection points of all curves fall in a small interval, and the intersection of any two curves represents the same changing rate of the horizontal ordinate, resulting in the maximum difference. The other is the dividing point, where the stretch ratio decreases on the left and increases on the right due to the introduction of friction. These results provide solid guidance and support for our understanding of the rigid–flexible contact behavior of inflated membrane balloons. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1772 KiB

Open AccessProceeding Paper

In-Situ Experimental Modal Testing of Railway Bridges

by Michael Reiterer, Stefan Lachinger, Josef Fink and Sebastian-Zoran Bruschetini-Ambro

Proceedings 2018, 2(8), 413; https://doi.org/10.3390/ICEM18-05286 - 30 May 2018

Cited by 3 | Viewed by 1707

In this paper the potential application of experimental modal testing of railway bridges by application of the forced vibration excitation method is proposed to identify reliable and reproduceable values of the natural frequencies and damping coefficients. It will be shown, that the damping [...] Read more.

In this paper the potential application of experimental modal testing of railway bridges by application of the forced vibration excitation method is proposed to identify reliable and reproduceable values of the natural frequencies and damping coefficients. It will be shown, that the damping values that are determined by in-situ experimental modal testing are in most cases significant higher than the values given in EN 1991-2 and that the normative damping values are quite conservative. The measuring results of a framed concrete bridge with 16.1 m span length are presented and the dependence of dynamic parameters to seasonable temperature changes and to the size of bridge vibration amplitude will be discussed in detail. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 687 KiB

Open AccessProceeding Paper

Mechanical Behaviour of Clinched Joints in Configurations

by Andreas Breda, Sam Coppieters and Dimitri Debruyne

Proceedings 2018, 2(8), 414; https://doi.org/10.3390/ICEM18-05280 - 31 May 2018

Cited by 2 | Viewed by 1657

Clinch joining or clinching is a mechanical joining technique for sheet material. In this paper, the mechanical behaviour of multiple clinched joints under mixed-mode loads (peel, shear and pull-out) is investigated using a modified Arcan test. The experimental results are compared with a [...] Read more.

Clinch joining or clinching is a mechanical joining technique for sheet material. In this paper, the mechanical behaviour of multiple clinched joints under mixed-mode loads (peel, shear and pull-out) is investigated using a modified Arcan test. The experimental results are compared with a proposed equivalent model for clinched joints to validate if the model can reproduce the deformation behaviour up to maximum force. The theoretical maximum resistance force of the configurations are then compared to the experimental maximum resistances to investigate the influence of interaction effects on the maximum strength of the configuration. This study is part of a global design strategy for clinched joints in large structures. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 849 KiB

Open AccessProceeding Paper

Numerical Investigations on the Fatigue Life of Lean Duplex Transverse Stiffeners in Bridges

by Burak Karabulut, Geert Lombaert, Dimitri Debruyne and Barbara Rossi

Proceedings 2018, 2(8), 415; https://doi.org/10.3390/ICEM18-05278 - 28 May 2018

Cited by 1 | Viewed by 1694

Numerical fatigue assessment of welded joints can be done using several approaches. The structural hot spot stress (SHSS) method based on finite element (FE) analysis is considered an effective approach when complex geometries or loading conditions exist. However, in the case of numerical [...] Read more.

Numerical fatigue assessment of welded joints can be done using several approaches. The structural hot spot stress (SHSS) method based on finite element (FE) analysis is considered an effective approach when complex geometries or loading conditions exist. However, in the case of numerical evaluation of the SHSS, the results can differ significantly depending on the FE modelling parameters. In the present paper, the sensitivity of the SHSS to several of these parameters is investigated numerically on one selected critical fatigue-prone detail, namely a transverse weld attachment, in a stainless steel bridge. In parallel a static tensile test performed on the same welded stainless steel detail is presented to measure the SHSS. The strain field near the welded area is measured with digital image correlation (DIC). The experimentally measured and numerically computed SHSS as well as the deduced fatigue lives are then compared and the sources of discrepancy discussed. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 558 KiB

Open AccessProceeding Paper

Nondestructive Damage Detection of a Magnetostrictive Composite Structure

by Asha Hall, Michael Coatney, Natasha Bradley, Jin Hyeong Yoo, Nicholas Jones, Brandon Williams and Oliver Myers

Proceedings 2018, 2(8), 416; https://doi.org/10.3390/ICEM18-05276 - 28 May 2018

Cited by 3 | Viewed by 1633

The integrity of composite structures gradually degrades due to the onset of damage such as matrix cracking, fiber/matrix debonding, and delamination. Over the last two decades, great strides have been made in structural health monitoring (SHM) community using various sensing techniques such as [...] Read more.

The integrity of composite structures gradually degrades due to the onset of damage such as matrix cracking, fiber/matrix debonding, and delamination. Over the last two decades, great strides have been made in structural health monitoring (SHM) community using various sensing techniques such as acoustic emission, eddy current, strain gages, etc., to diagnose damage in aerospace, mechanical and civil infrastructures. Embedded sensing offers the prospects of providing for real-time, in-service monitoring of damage were weight savings is a major factor in Aerospace Industry. In this present work, magnetostrictive particles such as Terfenol-D were embedded in a composite structure, along with multiple SHM techniques, to capture the damage in an IM7-carbon fiber reinforced polymer composite system undergoing fatigue loading. As the internal stress state increases, the change in the magnetization flux intensity was captured using a non-contact magnetic field sensor. A damage diagnosis system was established along with an acoustic emissions technique to further validate the damage captured by the embedded system. The goal of this project is to identify the change in the mechanical and magnetic property within a composite material during the evolution of damage. Several characterization techniques were used to determine interfacial fiber-matrix interactions which will provide for a more comprehensive understanding of the composite interfaces. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 826 KiB

Open AccessProceeding Paper

Experimental Characterization of Bond Fatigue Using Beam-End Tests with Push-In Loading

by Benjamin Camps, Abedulgader Baktheer, Josef Hegger and Rostislav Chudoba

Proceedings 2018, 2(8), 417; https://doi.org/10.3390/ICEM18-05270 - 24 May 2018

Cited by 5 | Viewed by 1798

Realistic characterization of fatigue loading resistance is a paramount for an economical and reliable structural design of reinforced concrete (RC) and prestressed concrete (PC) structures. The need for innovative experimental methods for the characterization of fatigue behavior is driven by the current aims [...] Read more.

Realistic characterization of fatigue loading resistance is a paramount for an economical and reliable structural design of reinforced concrete (RC) and prestressed concrete (PC) structures. The need for innovative experimental methods for the characterization of fatigue behavior is driven by the current aims to construct wind turbine towers that must resist up to N = 10⁷ loading cycles corresponding to 25 years of service life. Considering the number of possible configurations with regard to structural geometries, cross-sectional layout of reinforcement and loading scenarios, experimental data are required that capture the key mechanisms driving the fatigue damage between the reinforcement and concrete matrix. Experimental investigations of bond behavior under fatigue loading have been reported in the literature in the 90′s of last century. Since then, no systematic investigation of bond fatigue behavior has been published. As a consequence, no assessment rules are available for the bond fatigue, only separate assessment rules for concrete and steel. The present paper will report on the ongoing research of bond fatigue behavior using the beam-end test setup. The test campaign includes the push-in loading with the goal to provide data characterizing the compressive behavior of reinforced cross sections in wind turbine towers. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 773 KiB

Open AccessProceeding Paper

Development of Delamination Detection System for Concrete Decks by Using Convolutional Neural Network

by Takahiro Kashiwa, Kohei Nagai, Hitoshi Tatsuta, Helmut Prendinger, Kou Ibayashi and Juan José Rubio Guillamón

Proceedings 2018, 2(8), 418; https://doi.org/10.3390/ICEM18-05281 - 28 May 2018

Viewed by 1701

Bridges in Japan, especially those managed by municipalities, deteriorate over time. Due to lack of civil engineers in municipalities, appropriate and automated assistance for degradation judgement is thought to be important for the concerned authorities. Automated judgement systems for some types of damage [...] Read more.

Bridges in Japan, especially those managed by municipalities, deteriorate over time. Due to lack of civil engineers in municipalities, appropriate and automated assistance for degradation judgement is thought to be important for the concerned authorities. Automated judgement systems for some types of damage (e.g., cracks) started to be developed by geometrical approaches. Yet, there is no comprehensive method to detect more complicated types of damage, such as delamination, for regular inspection. This research aims to develop a delamination-detection system which identifies the location of the damage. Images with delaminated parts were provided by Niigata Prefecture (in Japan), and annotation of the location of delamination and/or rebar exposure was conducted. Fully Convolutional Network (FCN), one of the deep learning networks for pixel-to-pixel segmentation, was used to detect the areas of the delamination and rebar exposure. The result of the training aided by FCN showed a good agreement with the result with the naked eye. The soundness, judged based on the FCN result according to the inspection code of Niigata Prefecture, was close to the soundness judgement at the site. These outcomes support the reliability of the system to detect delamination and rebar exposure in manual inspection. This technology is expected to be used in bridges’ inspection at municipalities, which have a lack of inspection engineers. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 863 KiB

Open AccessProceeding Paper

Characterization of the Bond between Textile Reinforced Cement and Extruded Polystyrene by Shear Tests

by Jolien Vervloet, Panagiotis Kapsalis, Svetlana Verbruggen, Michael El Kadi, Matthias De Munck and Tine Tysmans

Proceedings 2018, 2(8), 419; https://doi.org/10.3390/ICEM18-05275 - 27 May 2018

Cited by 1 | Viewed by 1585

Loadbearing sandwich panels used as wall elements are a promising development since they combine structural and energy efficiency. Composite behaviour needs to be ensured so that the sandwich panel works as one element under a flexural load (meaning that the shear forces due [...] Read more.

Loadbearing sandwich panels used as wall elements are a promising development since they combine structural and energy efficiency. Composite behaviour needs to be ensured so that the sandwich panel works as one element under a flexural load (meaning that the shear forces due to bending are transferred from one face to the other). To assure this full composite behaviour, an investigation of the bond strength between the faces and the core of the sandwich panel is necessary. Therefore, two different bond test set-ups were performed on sandwich panels with Textile Reinforced Cement (TRC) faces and an Extruded Polystyrene (XPS) insulating foam core. The two bond test set-ups were compared and revealed that one of the set-ups showed a combination of bond and shear failure of the core so that a clear conclusion on the bond strength couldn’t be obtained. The second set-up showed clear bond failure and gave a good estimation of the bond strength between TRC and XPS. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 803 KiB

Open AccessProceeding Paper

Biaxial Compression Tests on Hopkinson Bars

by Bastien Durand, Ahmed Zouari and Han Zhao

Proceedings 2018, 2(8), 420; https://doi.org/10.3390/ICEM18-05263 - 24 May 2018

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A biaxial compression Hopkinson bar set-up bas been designed. It consists in a projectile, an input bar and two co-axial output bars. After the projectile impact on the input bar, the internal output bar measures the axial loading of the cross sample whereas [...] Read more.

A biaxial compression Hopkinson bar set-up bas been designed. It consists in a projectile, an input bar and two co-axial output bars. After the projectile impact on the input bar, the internal output bar measures the axial loading of the cross sample whereas the external output bar measures its transversal loading via a mechanism with sliding surfaces. Gauges glued on the bars enable stain measurements which lead to the forces and to the displacements on the interfaces between the bars and the mounting. The displacement field of the sample is obtained by high-speed imaging and by digital image correlation. Experiments show that the set-up works despites two disadvantages. Firstly, the transversal force in the sample is over-estimated because of the friction in the mechanism. Moreover, comparisons between the displacements on the bars interfaces and the sample displacement field display that the clearance have an influence on the sample loading. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 2669 KiB

Open AccessProceeding Paper

Combined ND Techniques for Structural Assessment: The Case of Historic Nepali Constructions after the 2015 Gorkha Earthquake

by Salvatore Russo, Domenico Liberatore and Luigi Sorrentino

Proceedings 2018, 2(8), 421; https://doi.org/10.3390/ICEM18-05271 - 27 May 2018

Cited by 2 | Viewed by 1751

Combined non-destructive in situ techniques—namely sonic tests and ambient vibration measurements—are applied on two Nepali Pagoda temples damaged by the 2015 Gorkha earthquake, providing the dynamic elastic modulus of masonry and the buildings’ frequencies Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1807 KiB

Open AccessProceeding Paper

A Novel Geometry for Shear Test Using Axial Tensile Setup

by Sibo Yuan, Laurent Duchêne, Olivier Milis, Clément Keller, Eric Hug and Anne-Marie Habraken

Proceedings 2018, 2(8), 422; https://doi.org/10.3390/ICEM18-05277 - 28 May 2018

Cited by 1 | Viewed by 1839

This paper studies a novel geometry for the in-plane shear test performed with an axial electromechanical testing machine. In order to investigate the influence of the triaxiality rate on the mechanical behavior, different tests will be performed on the studied material: simple tensile [...] Read more.

This paper studies a novel geometry for the in-plane shear test performed with an axial electromechanical testing machine. In order to investigate the influence of the triaxiality rate on the mechanical behavior, different tests will be performed on the studied material: simple tensile tests, large tensile tests and shear tests. For the whole campaign, a common equipment should be employed to minimize the impact of the testing device. As a consequence, for the shear tests, the geometry of the specimen must be carefully designed in order to adapt the force value and make it comparable to the one obtained for the tensile tests. Like most of the existing shear-included tensile test specimens, the axial loading is converted to shear loading at a particular region through the effect of geometry. A symmetric shape is generally preferred, since it can restrict the in-plane rotation of the shear section, keep shear increasing in a more monotonic path and double the force level thanks to the two shear zones. Due to the specific experimental conditions, such as dimensions of the furnace and the clamping system, the position of the extensometer or the restriction of sheet thickness (related to the further studies of size effect at mesoscale and hot temperature), several geometries were brought up and evaluated in an iterative procedure via finite element simulations. Both the numerical and experimental results reveal that the final geometry ensures some advantages. For instance, a relatively low triaxiality in the shear zone, limited in-plane rotation and no necking are observed. Moreover, it also prevents any out-of-plane displacement of the specimen which seems to be highly sensitive to the geometry, and presents a very limited influence of the material and the thickness. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 477 KiB

Open AccessProceeding Paper

Elasticity Constants of a Two-Phase Tungsten Thin Film

by Mohamed Fares Slim, Akram Alhussein and Manuel François

Proceedings 2018, 2(8), 423; https://doi.org/10.3390/ICEM18-05272 - 27 May 2018

Cited by 1 | Viewed by 1541

The IET was used to determine the macroscopic elasticity constants of the multiphase coating. In order to determine the macroscopic elasticity constants of the film firstly, a critical assessment of Young’s modulus determination was done by comparing all the models proposed in the [...] Read more.

The IET was used to determine the macroscopic elasticity constants of the multiphase coating. In order to determine the macroscopic elasticity constants of the film firstly, a critical assessment of Young’s modulus determination was done by comparing all the models proposed in the literature. The best model was identified and a study was performed to identify and quantify the most influent factors on the global uncertainty. Secondly, an enhanced formulation to determine the shear modulus of coating by IET was developed. The methodology was applied on a tungsten thin film deposited by DC magnetron sputtering. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 1544 KiB

Open AccessProceeding Paper

Experimental Investigation on the Explosive Substitute by Drop Test

by Ruoze Xie, Qingping Zhang, Zhifang Deng and Xicheng Huang

Proceedings 2018, 2(8), 424; https://doi.org/10.3390/ICEM18-05296 - 5 Jun 2018

Cited by 1 | Viewed by 1824

The drop tests of the experimental structure with explosive substitute material were carried out to study the dynamic deformation and failure of the explosive substitute. The PBX simulation material was designed as a cylindrical flat head structure, with the support structure of the [...] Read more.

The drop tests of the experimental structure with explosive substitute material were carried out to study the dynamic deformation and failure of the explosive substitute. The PBX simulation material was designed as a cylindrical flat head structure, with the support structure of the PBX simulation material as an aluminum support ring, and with an affixed counterweight to the upper part of the PBX simulation material. The PBX simulation materials, the counterweight and the support ring, were glued together to form the drop test pieces. A special drop test system was designed, which realized the non-deflection of the falling posture of the drop test pieces and that the drop was pure free. The results show that in the drop impact tests, the critical height of the explosive simulant failure is about 600 mm to 700 mm when the counterweight of 19.62 kg is used. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 624 KiB

Open AccessProceeding Paper

Robotic Welding Tests MIG Standard and CMT+P in Aluminum Alloy 6082-T6 for Optimization of Penetration, Cord Width and Reinforcement

by Arlindo Pascoal, A. Eduardo Izeda, Vinícius Cecilio, Nuno Mineiro, José Gonçalves and João E. Ribeiro

Proceedings 2018, 2(8), 425; https://doi.org/10.3390/ICEM18-05295 - 5 Jun 2018

Cited by 3 | Viewed by 1867

The present article describes an experimental analysis of a robotized Gas Metal-arc Welding (GMAW) in aluminum alloy, using Metal Inert Gas (MIG) in its transfer method variation Standard and pulsed Cold Metal Transfer (CMT+P), developed in order to optimize the penetration depth, width [...] Read more.

The present article describes an experimental analysis of a robotized Gas Metal-arc Welding (GMAW) in aluminum alloy, using Metal Inert Gas (MIG) in its transfer method variation Standard and pulsed Cold Metal Transfer (CMT+P), developed in order to optimize the penetration depth, width and reinforcement of the weld bead. The base metal was the aluminum alloy 6082-T6 and the filler metal was aluminum alloy 5754. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 471 KiB

Open AccessProceeding Paper

Optimization of Robotized Welding in Aluminum Alloys with Pulsed Transfer Mode Using the Taguchi Method

by A. Eduardo Izeda, Arlindo Pascoal, Guilherme Simonato, Nuno Mineiro, José Gonçalves and João E. Ribeiro

Proceedings 2018, 2(8), 426; https://doi.org/10.3390/ICEM18-05294 - 8 Jun 2018

Cited by 3 | Viewed by 1859

In order to obtain an optimal combination of welding parameters to weld an aluminum alloy (6082-T6) with MIG (Metal Inert Gas) it was used an L27 Taguchi orthogonal array. The array originated 27 different combinations that gives rise to 27 welding programs for [...] Read more.

In order to obtain an optimal combination of welding parameters to weld an aluminum alloy (6082-T6) with MIG (Metal Inert Gas) it was used an L27 Taguchi orthogonal array. The array originated 27 different combinations that gives rise to 27 welding programs for the metal pulsed spray mode. The welds were made in aluminum bars using an industrial robot. All welds were repeated three times to ensure string repeatability. Metallographic tests were performed on the weld beads for measuring the width bead, penetration and reinforcement. Measurement data was analyzed for signal/noise and analysis of variance (ANOVA). Applying the Taguchi’s method, an optimal combination of welding parameters was reached. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 248 KiB

Open AccessProceeding Paper

A Novel Strategy to Achieve Enhanced Reinforcement and Decreased Damping in CNT-Nanocomposites

by Maryam Karimzadeh, Michela Talò, Walter Lacarbonara and Giulia Lanzara

Proceedings 2018, 2(8), 427; https://doi.org/10.3390/ICEM18-05293 - 5 Jun 2018

Viewed by 1373

In recent decades, polymer-carbon nanotube (CNTs) composite materials have drawn much attention for their potential applications as nanofiller in unique lightweight materials with superior mechanical properties. For structural engineering applications, high strength and stiffness can be delivered and conveniently tuned in nanocomposites by [...] Read more.

In recent decades, polymer-carbon nanotube (CNTs) composite materials have drawn much attention for their potential applications as nanofiller in unique lightweight materials with superior mechanical properties. For structural engineering applications, high strength and stiffness can be delivered and conveniently tuned in nanocomposites by ensuring and effective load-transfer at the CNT/polymer interfaces. To achieve such an improvement, conventional approaches are based on complex chemical functionalization processes. In this work, the mechanical properties of nickel-coated carbon nanotube (Ni-CNT) reinforced polyamic acid-nanocomposites (Ni-CNTs /PAA) are presented and compared to those of pristine CNT nanocomposites (CNTs/PAA) in terms of stiffness, strength and damping capacity. The Ni nanoparticles decorating the CNTs outer walls induce an interlocking mechanism at the CNTs/matrix interface. A significant increase in the elastic modulus is thus observed for this kind of materials. On the other hand, the Ni-CNTs/PAA nanocomposite, decreases its damping capacity when compared with pristine CNTs/PAA nanocomposite. It is worth noting that the two investigated nanocomposites were conceived with the same total weight fraction of nanofiller, by assuming as nanofiller the pristine CNTs and the Ni-coated CNTs, respectively. The recorded stiffness enhancement and damping reduction are reached despite the significantly smaller amount of CNTs contained in the Ni-coated CNT nanocomposite samples. Indeed, for these nanocomposites, Ni nanoparticles, with their higher mass density, represent the 60 wt% of the total nanofiller weight. The results proved the concept that when metal nanoparticles coat the CNTs outer walls, better CNTs/matrix adhesion can be achieved without the need to undergo complex CNTs functionalization procedures. This is an advantage since chemical functionalization typically shows the drawback of damaging the CNTs, by introducing defects on their outer walls. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 970 KiB

Open AccessProceeding Paper

Blast Loading of Concrete Pipes Using C-4 Charges

by Martin Kristoffersen, Knut Ove Hauge and Tore Børvik

Proceedings 2018, 2(8), 428; https://doi.org/10.3390/ICEM18-05292 - 8 Jun 2018

Cited by 3 | Viewed by 2458

The E39 coastal highway route in Norway is envisioned a future without ferries. A submerged floating tunnel built in concrete has been suggested as a means of crossing wide and deep fjords. Blast loading against this type of structure could have disastrous consequences, [...] Read more.

The E39 coastal highway route in Norway is envisioned a future without ferries. A submerged floating tunnel built in concrete has been suggested as a means of crossing wide and deep fjords. Blast loading against this type of structure could have disastrous consequences, and potentially cause the collapse of the entire structure. To investigate the response of tubular concrete structures subjected to blast loading, standard off-the-shelf unreinforced concrete pipes were tested using live explosives. A plastic explosive was used to generate the load, and the tests were filmed by two synchronised high-speed cameras. Three pressure sensors equidistant from the charge position logged the pressure. Further, three different positions for the charges were used to investigate the effect of charge position. The charge size was varied for each position to find the amount of explosives needed to breach the pipe. It was found that a contact charge detonated from the outside requires almost twice the explosive amount to breach the pipe than a contact charge detonated from the inside, suggesting a significant confinement effect. Numerical simulations using finite elements produced good qualitative results. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2447 KiB

Open AccessProceeding Paper

Experimental Investigation on Crack Growth in Pre-Notched Concrete Beams

by Giuseppe Lacidogna, Gianfranco Piana, Federico Accornero and Alberto Carpinteri

Proceedings 2018, 2(8), 429; https://doi.org/10.3390/ICEM18-05287 - 1 Jun 2018

Cited by 1 | Viewed by 1763

It is well-known that failure of unreinforced, pre-notched concrete beams in bending is mainly governed by the tensile strength (“ductile” behaviour) or by the fracture toughness (brittle behaviour) depending on the geometrical scale (beam size), and the value of the relative notch depth. [...] Read more.

It is well-known that failure of unreinforced, pre-notched concrete beams in bending is mainly governed by the tensile strength (“ductile” behaviour) or by the fracture toughness (brittle behaviour) depending on the geometrical scale (beam size), and the value of the relative notch depth. In particular, relatively large beams made of high-strength concrete and with a small relative notch depth, show a brittle structural behaviour (unstable crack propagation); whereas relatively small beams made of low-strength concrete and with a large relative notch depth, show a relatively ductile structural behaviour (stable crack propagation). In this contribution, the damage progress, due to crack formation and propagation, in unreinforced, pre-notched concrete beam specimens, tested in three-point bending, is analysed by the Acoustic Emission (AE) and Digital Image Correlation (DIC) techniques. Beams with rectangular cross-section were considered. A relative notch depth (a/d) equal to 0.5 is assumed in all cases. The loading process was operated by controlling the vertical displacement. The specimens were instrumented by four transducers measuring the vertical displacements in correspondence to the supports and at mid-span, and the Crack Mouth Opening Displacement (CMOD). In addition, two AE transducers were located near the notch to acquire the AE signals originated by material damage. Moreover, the evolution of the deformation process was monitored around the notch by a DIC system, therefore obtaining the time evolution of strains. By analysing the acquired data, a correlation between the AE signals registered and the displacements/strains measured at several points was looked for. Furthermore, the fracture energy of each specimen was evaluated, according to RILEM recommendation, based on the measured load–deflection curves. Scale effects on fracture energy, bending strength, and AE energy per unit area were investigated. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 993 KiB

Open AccessProceeding Paper

Digital Image Correlation Measurements of Mode I Fatigue Delamination in Laminated Composites

by Man Zhu, Larissa Gorbatikh, Sander Fonteyn, Lincy Pyl, Danny Van Hemelrijck, Delphine Carrella-Payan and Stepan V. Lomov

Proceedings 2018, 2(8), 430; https://doi.org/10.3390/ICEM18-05289 - 4 Jun 2018

Cited by 2 | Viewed by 1960

A Digital Image Correlation (DIC) based method is proposed to characterize Mode I fatigue delamination onset and propagation in laminated composites. With the help of DIC, the displacement field around a delamination crack is obtained and further processed to determine the position of [...] Read more.

A Digital Image Correlation (DIC) based method is proposed to characterize Mode I fatigue delamination onset and propagation in laminated composites. With the help of DIC, the displacement field around a delamination crack is obtained and further processed to determine the position of the crack tip. With this method the delamination length can be measured automatically in each cycle with a precision on the order of few hundreds of micrometers. The fatigue delamination onset life is then determined by detecting the increase of the delamination length, and the fatigue delamination propagation rate is calculated. The proposed method produces more conservative fatigue life measurements in comparison with the compliance increase method in ASTM D6115. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 500 KiB

Open AccessProceeding Paper

Experimental Study on the Strength of Stainless Steel Fillet Welds

by Maarten Fortan, Arnout Dejans, Dimitri Debruyne and Barbara Rossi

Proceedings 2018, 2(8), 431; https://doi.org/10.3390/ICEM18-05290 - 8 Jun 2018

Cited by 4 | Viewed by 1653

This paper describes 18 tensile tests performed on welded specimens made of 3 stainless steel grades: EN 1.4307 (304L) and EN 1.4404 (316L) austenitic grades and EN 1.4062 duplex grade. For each grade, 3 tests were carried out parallel to the weld causing [...] Read more.

This paper describes 18 tensile tests performed on welded specimens made of 3 stainless steel grades: EN 1.4307 (304L) and EN 1.4404 (316L) austenitic grades and EN 1.4062 duplex grade. For each grade, 3 tests were carried out parallel to the weld causing shear stresses (in the weld throat plane, parallel to the weld throat axis) and 3 tests along the transverse direction, perpendicular to the weld, causing a combination of normal (perpendicular to the weld throat plane) and shear (in the weld throat plane, perpendicular to the weld throat axis) stresses. The digital image correlation (DIC) technique was used to measure the fracture surface. Based on these experiments, an assessment of the current design rules was made. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1721 KiB

Open AccessProceeding Paper

Use of Spectral Entropy for Damage Detection in Masonry Buildings in the Presence of Mild Seismicity

by Rosario Ceravolo, Erica Lenticchia and Gaetano Miraglia

Proceedings 2018, 2(8), 432; https://doi.org/10.3390/ICEM18-05288 - 4 Jun 2018

Cited by 5 | Viewed by 1713

The seismic events that struck central Italy in 2016 caused severe damage to a wide range of buildings and infrastructures. Masonry buildings were particularly affected, even for low values of peak ground acceleration. In this paper, the data recorded for three masonry buildings [...] Read more.

The seismic events that struck central Italy in 2016 caused severe damage to a wide range of buildings and infrastructures. Masonry buildings were particularly affected, even for low values of peak ground acceleration. In this paper, the data recorded for three masonry buildings belonging to the Seismic Observatory of Structures (OSS) network are used to detect their seismic damage by means of Spectral Entropy (SE). However, entropy measures are sensitive to the energy inserted in the system, since an input of energy can lead to a more deterministic behavior of the structure and thus to a reduction of the entropy indicator. When non-stationary time series are used to evaluate the presence of damage (e.g. mild seismicity) the entropy of the system could be underestimated, leading to misleading results. For these reasons, in this paper an indicator based on SE is proposed to assess the occurrence of damage also in the presence of mild seismicity. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 1919 KiB

Open AccessProceeding Paper

Evaluation of Crack Repair Effect for RC Slab Using AE Tomography

by Nobuhiro Okude, Tomoki Shiotani, Takahiro Nishida, Katsufumi Hashimoto and Syogo Furuno

Proceedings 2018, 2(8), 433; https://doi.org/10.3390/ICEM18-05331 - 11 Jun 2018

Cited by 2 | Viewed by 1928

Three reinforced concrete (RC) slab-panels are repaired by using the crack injection method. This is because web-shaped crack networks are observed after 46 years in service. In the present research, an attempt is made to confirm the effectiveness of the repair by comparing [...] Read more.

Three reinforced concrete (RC) slab-panels are repaired by using the crack injection method. This is because web-shaped crack networks are observed after 46 years in service. In the present research, an attempt is made to confirm the effectiveness of the repair by comparing the velocity distribution of elastic waves obtained from Acoustic Emission (AE) tomography analysis, before and after the repair. Thus, the velocity recoveries due to injection are found in all of the slab panels, and it is confirmed that the elastic wave velocities obtained using this technique can serve as an indicator for examining the state of crack and void filling with injected material. Further, a good correlation is found between the low-velocity region before repair and the amount of injection. These results show the potential of the AE tomography technique to be used as a method for estimating the effect of injection repair. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2353 KiB

Open AccessProceeding Paper

Stress Measurement by Spectrum Analyses for Round Bar Subjected to Time-Varying Load

by Tsutomu Yoshida, Kyo Shinkou, Kunihiko Sakurada and Takeshi Watanabe

Proceedings 2018, 2(8), 434; https://doi.org/10.3390/ICEM18-05323 - 11 Jun 2018

Viewed by 1297

In this research, a feasibility study to measure the magnitude and cycle of the time-varying stress of a specimen using the natural frequency was carried out. An experiment was conducted. We used a round bar with 8 mm diameter and 290 mm span [...] Read more.

In this research, a feasibility study to measure the magnitude and cycle of the time-varying stress of a specimen using the natural frequency was carried out. An experiment was conducted. We used a round bar with 8 mm diameter and 290 mm span length as a specimen, which was fixed at both ends. A sinusoidal axial stress was applied to the bar. The deflection of the bar in free vibration was measured using a laser beam displacement device. To collect more information on the deflection, a device was made, which hit the bar periodically. The fast Fourier transform method, short-time Fourier transform method and wavelet analysis were applied to the deflection. The methods gave us relations among time, frequency and magnitude of the signal, with complicated representations. Applying the analyses to the experimental data, we tried to evaluate the magnitude and cycle of a time-varying load. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1068 KiB

Open AccessProceeding Paper

Towards a Phased Array Based Ultrasonic Polar Scan: Simulation Study and Comparison with Plane Wave Results

by Jannes Daemen, Arvid Martens, Mathias Kersemans, Erik Verboven, Steven Delrue, Wim Van Paepegem and Koen Van Den Abeele

Proceedings 2018, 2(8), 435; https://doi.org/10.3390/ICEM18-05327 - 11 Jun 2018

Viewed by 1739

The ever-increasing use of composite materials in the industry has resulted in the need for new, intricate approaches to not only properly characterize their anisotropic mechanical properties (i.e., the visco-elastic tensor), but also to detect various types of internal flaws. Both goals can [...] Read more.

The ever-increasing use of composite materials in the industry has resulted in the need for new, intricate approaches to not only properly characterize their anisotropic mechanical properties (i.e., the visco-elastic tensor), but also to detect various types of internal flaws. Both goals can be achieved by the Ultrasonic Polar Scan (UPS). During an UPS experiment, a material spot is insonified at many oblique incidence angles Ψ(θ,φ), with θ the vertical incident angle and φ the in-plane polar angle, after which the reflected or transmitted ultrasound signal is recorded. The resulting dataset provides an integral view of the angle-dependent reflection (R) and transmission (T) scatter coefficients, and can be employed to infer the material properties. Although the current UPS scanner provides highly accurate experimental data, it is impractical for in-situ measurements. In order to create a more compact and practical measuring device, we propose the use of a hemispherical phased array, consisting of small piezoelectric elements, to generate a broadband, quasi plane wave signal. It will be shown, based on simulations, that a circular phased array concept allows for the determination of the reflection coefficients in θ − f space, from which the dispersion curves can be immediately inferred. Comparison of these results with the plane wave theoretical results show an excellent agreement. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1079 KiB

Open AccessProceeding Paper

Experimental Analysis of CFRP Strengthened Reinforced Concrete Slabs Loaded by Two Independent Explosions

by Azer Maazoun, Stijn Matthys, Bachir Belkassem, David Lecompte and John Vantomme

Proceedings 2018, 2(8), 436; https://doi.org/10.3390/ICEM18-05317 - 11 Jun 2018

Cited by 2 | Viewed by 1872

The use of carbon fiber reinforced polymer (CFRP) as an externally bonded reinforcement (EBR) for the strengthening of reinforced concrete (RC) structures loaded by a blast wave is confirmed as an efficient solution. This observation is complementary to other advantages of CFRP such [...] Read more.

The use of carbon fiber reinforced polymer (CFRP) as an externally bonded reinforcement (EBR) for the strengthening of reinforced concrete (RC) structures loaded by a blast wave is confirmed as an efficient solution. This observation is complementary to other advantages of CFRP such as high tensile strength, light weight and durability. This paper discusses the behavior of CFRP as EBR in the event that two successive independent blast loads are applied on the same target. The main problems are the lack of knowledge regarding the failure modes of the CFRP strips under high strain rate and the blast response of the retrofitted structures when total debonding of the CFRP strips occurs. Four simply supported slabs with different EBR but with the same bond contact surface are tested using an explosive driven shock tube (EDST) to generate the blast wave. Digital image correlation (DIC) is used to measure the strain evolution in the concrete and the CFRP strips during the first explosion. The results show that for the first explosion, EBR increases the flexural strength and stiffness of the RC slabs. In the second explosion, total debonding of the CFRP strips occurs which initiates from the midspan of the slabs towards the supports. When the total debonding of the CFRP strips occurs, the strain distribution in the steel rebars are the same for all slabs regardless of the quantity of applied EBR. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 669 KiB

Open AccessProceeding Paper

Comparison of Non-Destructive Techniques for Impact Damage Area Assessment in Aramid/Epoxy Composites

by Andrea Manes, Stephanie Nunes, Álvaro González-Jiménez, Sandro Amico and Marco Giglio

Proceedings 2018, 2(8), 437; https://doi.org/10.3390/ICEM18-05320 - 11 Jun 2018

Cited by 3 | Viewed by 1516

This research focused on the assessment of the damaged area on aramid/epoxy composites subjected to high velocity impact. Digital X-ray radiography and active pulsed thermography techniques were used for performing post-mortem analysis of the impacted specimens (8 to 28 aramid layers). Two types [...] Read more.

This research focused on the assessment of the damaged area on aramid/epoxy composites subjected to high velocity impact. Digital X-ray radiography and active pulsed thermography techniques were used for performing post-mortem analysis of the impacted specimens (8 to 28 aramid layers). Two types of projectiles were used: 9 mm Luger FMJ and 0.357 Magnum FMJ. Two types of dedicated algorithms were developed to post-process the thermograms obtained and the results are compared with the damaged diameter measured directly on the X-ray radiographs. The output of the three methods are therefore compared and discussed. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1018 KiB

Open AccessProceeding Paper

Effect of Loading Pattern on Fatigue Behavior of Laminated Composites

by Abdolvahid Movahedi-Rad, Thomas Keller and Anastasios P. Vassilopoulos

Proceedings 2018, 2(8), 438; https://doi.org/10.3390/ICEM18-05321 - 12 Jun 2018

Viewed by 1539

The effect of load interruptions on the fatigue behavior of (±45)_2s angle-ply glass/epoxy composite laminates was investigated in this work. Constant amplitude fatigue experiments were performed at different stress levels to derive base line fatigue data. In addition, interrupted-fatigue experiments were performed [...] Read more.

The effect of load interruptions on the fatigue behavior of (±45)_2s angle-ply glass/epoxy composite laminates was investigated in this work. Constant amplitude fatigue experiments were performed at different stress levels to derive base line fatigue data. In addition, interrupted-fatigue experiments were performed by removing the cyclic loading for two hours repetitively, after cycling for 20% of the fatigue life achieved under continuous loading at the same maximum cyclic stress level. The specimens loaded under interrupted fatigue exhibited longer fatigue live than those continuously loaded until failure. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 528 KiB

Open AccessProceeding Paper

Excitation Source Optimisation for Active Thermography

by Simon Verspeek, Jeroen Peeters, Bart Ribbens and Gunther Steenackers

Proceedings 2018, 2(8), 439; https://doi.org/10.3390/ICEM18-05325 - 11 Jun 2018

Cited by 1 | Viewed by 1652

In active thermography, the use of an optimised excitation source can simplify the interpretation of measurement results. Our custom designed source, especially designed for dynamic line scanning thermography, minimises the needed excitation power and the biasing side effects generated by a wide-range heat [...] Read more.

In active thermography, the use of an optimised excitation source can simplify the interpretation of measurement results. Our custom designed source, especially designed for dynamic line scanning thermography, minimises the needed excitation power and the biasing side effects generated by a wide-range heat source. The source is redesigned, starting from a regular heat source, to focus the available energy such that the needed heating power is provided in a small band. Ray tracing software is used to design absorbers and reflectors to focus the electromagnetic radiation as well as the heat in a thin line. The most optimal design is manufactured and validated on a laminated test sample. The acquired thermographic data are then compared to the data captured in the old-fashioned way with widely available excitation sources. The redesign is also tested on durability and practical use to make sure that it is easy to handle and that it can be used as a long-term solution. Experienced inspectors evaluated the ease of use of it in comparison to the existing sources. A redesigned excitation source minimises the generated biasing side-effects resulting in more energy efficient and safer measurements. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2216 KiB

Open AccessProceeding Paper

Thermoelectric Powered Security Systems in Iceland Using a Geothermal Steam Pipe as a Heat Source

by Robert Dell, Chih S. Wei, Michael Thomas Petralia, Gudmundur Gislason and Runar Unnthorsson

Proceedings 2018, 2(8), 440; https://doi.org/10.3390/ICEM18-05309 - 8 Jun 2018

Cited by 4 | Viewed by 3287

Geothermal bore holes and steam pipes are often in remote locations where normal powering methods for monitoring systems are difficult due to distance from the electrical grid. Solar power options are limited during the winter months, and colder temperatures are detrimental to stand-alone [...] Read more.

Geothermal bore holes and steam pipes are often in remote locations where normal powering methods for monitoring systems are difficult due to distance from the electrical grid. Solar power options are limited during the winter months, and colder temperatures are detrimental to stand-alone batteries. The authors have successfully field tested their patented thermoelectric generator in Hveragerdi at the Agricultural University of Iceland. It was retrofitted directly to the surface of a geothermal steam pipe in less than 30 minutes. The generator can produce more than 5 watts (W) in steady state in an environment which has a delta T of 130 °C between the ambient air temperature and the surface of the steam pipe. Cellular video surveillance systems, rudimentary control systems, and small robotic systems have been powered while trickle charging 12 volt (V) 9 ampere-hour (Ah) lead acid batteries. Recent applications use a standard commercially available 3G mobile broadband connection with a low power modem for a web cam. The charged batteries can be used for peak power applications. Reliability studies are in progress and additional options will be investigated. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 4514 KiB

Open AccessProceeding Paper

Assessment of Environmental Effects for Vibration-Based Damage Detection of Historic Masonry Towers

by Carmelo Gentile and Antonella Saisi

Proceedings 2018, 2(8), 441; https://doi.org/10.3390/ICEM18-05324 - 11 Jun 2018

Cited by 1 | Viewed by 1792

The paper firstly focuses on selected results obtained by continuously monitoring the dynamic response of three ancient masonry towers in Italy in order to highlight the possible effects of changing temperature on the resonant frequencies; subsequently, the removal of environmental effects (needed for [...] Read more.

The paper firstly focuses on selected results obtained by continuously monitoring the dynamic response of three ancient masonry towers in Italy in order to highlight the possible effects of changing temperature on the resonant frequencies; subsequently, the removal of environmental effects (needed for an effective performance assessment and damage detection) is addressed and discussed using the data acquired on a challenging historic tower. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1584 KiB

Open AccessProceeding Paper

Influence of Charge Backing on the Response of Blast Loaded Plates

by Richard Curry and Genevieve Langdon

Proceedings 2018, 2(8), 442; https://doi.org/10.3390/ICEM18-05312 - 12 Jun 2018

Cited by 1 | Viewed by 1527

This study focuses on characterizing the transient deformation of test plates which have been exposed to air blasts arising from air-backed and metal-backed explosive detonations. Four charge masses are considered, namely 10 g, 15 g, 20 g and 25 g masses of PE4 [...] Read more.

This study focuses on characterizing the transient deformation of test plates which have been exposed to air blasts arising from air-backed and metal-backed explosive detonations. Four charge masses are considered, namely 10 g, 15 g, 20 g and 25 g masses of PE4 plastic explosive which were moulded into cylindrical charges of a constant 38 mm diameter. The transient deformation of the test plates was captured using high speed Digital Image Correlation (DIC), which utilized two high speed cameras to record the experiments. The experimental plates exhibited plastic deformation with no tearing. The impulse imparted to the test plates increased fivefold when the charge was metal-backed. The permanent deflections from the metal-backed detonations were larger than for air, but not to the same degree as the impulse increase. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 1452 KiB

Open AccessProceeding Paper

Study on the Identifiability of Material Properties Using Solely the Residual Imprint in Instrumented Indentation Experiment

by Mingzhi Wang and Jianjun Wu

Proceedings 2018, 2(8), 443; https://doi.org/10.3390/ICEM18-05316 - 12 Jun 2018

Cited by 2 | Viewed by 1468

Indentation test has been widely used to determine the mechanical properties of materials. In the present work, based on our previous developed inverse computation approach, we investigated the identifiability of the plastic properties of metal materials using solely the residual imprint in instrumented [...] Read more.

Indentation test has been widely used to determine the mechanical properties of materials. In the present work, based on our previous developed inverse computation approach, we investigated the identifiability of the plastic properties of metal materials using solely the residual imprint in instrumented indentation. The indentation experiment was implemented on the Al 2024-t3 alloy, and result shows the experiment error exists unavoidably. To quantitatively investigate the influence of experiment error on the inverse derived material properties, the indentation simulation models were built, of which three different indenter shapes (conical, flat and spherical) and two different simulation set-ups (load or displacement control types) are considered. The sensitivity of the inverse problem in the relevant questions are systematically investigated. Results show the inverse problem formulated by the force control using a non-self-similar indenter is able to give more robust solution of the inverse derived material parameters. Besides, the numerical protocol was verified by application on the Al 2024-t3 alloy, and the plastic properties (yield stress and strain hardening exponent) obtained from indentation and uniaxial tests show good agreement. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 5260 KiB

Open AccessProceeding Paper

Combined Error Elimination for Three Dimensional Thermal Images Using Hybrid Digital Holography

by IkHwan Kwon, Hyunchul Jung, SeolHee Yi, KyeongSuk Kim, KiYoul Kim and ChungKi Hong

Proceedings 2018, 2(8), 444; https://doi.org/10.3390/ICEM18-05378 - 21 Jun 2018

Cited by 1 | Viewed by 1455

This paper discusses a method for eliminating geometric optics errors that can occur when combining three-dimensional thermal images using hybrid digital holography. We obtained reconstructed digital holography using phase detection autofocus technique and arbitrary tilt plane correction. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2486 KiB

Open AccessProceeding Paper

Application of Digital Image Correlation to Cement Paste

by Evin Dildar Dzaye, Geert De Schutter and Dimitrios Aggelis

Proceedings 2018, 2(8), 446; https://doi.org/10.3390/ICEM18-05332 - 12 Jun 2018

Cited by 2 | Viewed by 1842

In this paper digital image correlation (DIC) has been applied to study the deformation process of cementitious material at very early age. After mixing of cement-based materials, the cement hydration process begins. Consequently, the ongoing chemical reactions result in a 3D deformation process [...] Read more.

In this paper digital image correlation (DIC) has been applied to study the deformation process of cementitious material at very early age. After mixing of cement-based materials, the cement hydration process begins. Consequently, the ongoing chemical reactions result in a 3D deformation process (shrinkage). The mechanism affecting the very early age hydration as well as specifically the deformation behavior of cementitious materials is a challenging topic. In view of that, it is essential to determine the significant effect of concrete hardening process on the deformation progression at different stages. The technique of DIC is highly sensitive and allows for the first time in literature an accurate and non-contact optical monitoring of the shrinkage of fresh cementitious material. The displacement of the surface is measured by correlating the different digital images taken at different ages after mixing of the material. The system enables a 3D observation that allows a deeper understanding of the deformation progression. The surface displacement determined by DIC-software (Vic-Snap 2010) is compared to the displacement measured by Linear variable differential transformer (LVDT) sensors for calibration purposes. DIC system realizes a more precise method avoiding the effect of self-weight of the traditional sensor. The purpose of this work is to check the sensitivity as well as the effectiveness of DIC technique, to characterize and better understand the 3D deformation process of fresh cementitious materials. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 283 KiB

Open AccessProceeding Paper

Considerations of Failure Analysis in a Multi-Layered Composite Structure under Thermomechanical Loading

by Ngeletshedzo Nyambeni and Boy Raymond Mabuza

Proceedings 2018, 2(8), 447; https://doi.org/10.3390/ICEM18-05329 - 12 Jun 2018

Cited by 6 | Viewed by 1705

The study seeks to investigate a failure of laminated composite structure subjected to a thermomechanical loading. Failure analysis of composite structures is an important design requirement. The stacking sequence of the structure investigated is restricted to ten thin layers. The fiber orientation, stacking [...] Read more.

The study seeks to investigate a failure of laminated composite structure subjected to a thermomechanical loading. Failure analysis of composite structures is an important design requirement. The stacking sequence of the structure investigated is restricted to ten thin layers. The fiber orientation, stacking sequence and material properties influence the response from the composite structure. Formulas are presented which are used to estimate the response of multi-layered composite structure to thermomechanical loads. A failure analysis is performed based on some known failure criteria. The values of the engineering properties for multi-layered composite structure and the results of the stress and strain distributions subjected to the forces and bending moments are presented. The numerical results were computed by using MATLAB script. Selected results of the numerical analysis have been presented. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1673 KiB

Open AccessProceeding Paper

On the Influence of Experimental Parameters on the Consistency of the LDR-Based Defect Detection Approach Applied to Composite Material Structures

by Galid Arroud, Mahmoud El-Kafafy and Patrick Guillaume

Proceedings 2018, 2(8), 448; https://doi.org/10.3390/ICEM18-05330 - 11 Jun 2018

Cited by 1 | Viewed by 1471

The Local Defect Resonance (LDR) approach is a technique which is used to detect and localize defects in structural components in a non-invasive way. In this contribution, we will assess whether the local resonance frequencies changes by altering a set of experimental testing [...] Read more.

The Local Defect Resonance (LDR) approach is a technique which is used to detect and localize defects in structural components in a non-invasive way. In this contribution, we will assess whether the local resonance frequencies changes by altering a set of experimental testing conditions (i.e., imposed boundary condition, number of excitation points and excitation location). The specimen is made of a carbon fiber reinforced polymer and contains multiple flat bottom holes. However, here, we will focus on three detectable defects. The measured response analyzed through a parametric data-processing approach confirms that the local resonance frequencies are independent of the proposed changes. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 700 KiB

Open AccessProceeding Paper

Experimental Techniques Synergy towards the Design of a Sensing Tool for Autonomously Healed Concrete

by Eleni Tsangouri, Dimitrios G. Aggelis, Nele De Belie, Tomoki Shiotani and Danny Van Hemelrijck

Proceedings 2018, 2(8), 449; https://doi.org/10.3390/ICEM18-05310 - 12 Jun 2018

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The first-generation of autonomously healed concrete elements is under construction: beams (SIM-SECEMIN project, Flanders Belgium), one-way flat slabs (MeMC, VUB, Belgium) and wall panels (Materials4Life project, UK) are designed with the embedment of encapsulated repair agent. In the presence of cracks, capsules rupture [...] Read more.

The first-generation of autonomously healed concrete elements is under construction: beams (SIM-SECEMIN project, Flanders Belgium), one-way flat slabs (MeMC, VUB, Belgium) and wall panels (Materials4Life project, UK) are designed with the embedment of encapsulated repair agent. In the presence of cracks, capsules rupture releasing the agent that fills the crack void. The released agent seals and mechanically restores the crack discontinuity. This automatic process can be repeatable using vascular networks that carry the agent and release it at different locations into concrete. The innovative design is built up following several series of laboratory-scale beam tests configured over the last decade. This paper discusses the application of numerous experimental techniques that assess the mechanical performance of autonomously healed concrete: Acoustic Emission, Ultrasound Pulse Velocity, Optical Microscopy, Digital Image Correlation, Capillary Water Absorption, Computed Tomography. The study focuses on the performance and efficiency of each method on laboratory and real-scale tests. The techniques with the most promising output are selected and combined in order to design a sensing tool that evaluates healing on real applications. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 806 KiB

Open AccessProceeding Paper

Creep Life Prediction Method by Using High-Temperature Indentation Creep Test

by Kiyohiro Ito, Hiroki Yajima and Masayuki Arai

Proceedings 2018, 2(8), 450; https://doi.org/10.3390/ICEM18-05319 - 11 Jun 2018

Cited by 1 | Viewed by 2196

Creep life prediction is very important to maintain safe operation of thermal power plants for a long-term period. In this study, an alternative creep life prediction method was proposed based on a relationship between creep exponent n and creep coefficient k. A [...] Read more.

Creep life prediction is very important to maintain safe operation of thermal power plants for a long-term period. In this study, an alternative creep life prediction method was proposed based on a relationship between creep exponent n and creep coefficient k. A high temperature indentation creep test was conducted to identify the creep exponent and creep coefficient for each specimen with different creep damage ratio. Subsequently, the relationship between the creep coefficient and creep exponent for each creep damage ratio was focused on. As a result, it was confirmed that a new parameter B introduced based on both creep coefficient and creep exponent linearly increase as the creep damage ratio increases. Furthermore, the B is uniquely determined by the creep damage ratio regardless of the temperature and stress conditions. These results indicate that the creep life can be predicted with a high accuracy using the B. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 3032 KiB

Open AccessProceeding Paper

Using 3D Digital Image Correlation (3D-DIC) to Measure CTOD in a Semi-Elliptical Surface Crack

by Kaveh Samadian, Stijn Hertelé and Wim De Waele

Proceedings 2018, 2(8), 451; https://doi.org/10.3390/ICEM18-05311 - 8 Jun 2018

Cited by 2 | Viewed by 2438

The subsurface nature of Crack Tip Opening Displacement (CTOD) makes its direct measurement very difficult, if not impossible. During fracture toughness testing, CTOD is commonly calculated by applying a plastic hinge model using externally applied clip gauges. However, clip gauge CTOD calculations merely [...] Read more.

The subsurface nature of Crack Tip Opening Displacement (CTOD) makes its direct measurement very difficult, if not impossible. During fracture toughness testing, CTOD is commonly calculated by applying a plastic hinge model using externally applied clip gauges. However, clip gauge CTOD calculations merely provide information relating to the center of the defect (which is typically the most critical point, but not always). For the case of a finite-length surface defect, CTOD will be variable over the defect front. Exact knowledge of CTOD over the entire front is useful for detailed calculations, such as crack profile evolution due to ductile tearing or calculations involving interacting defects. To experimentally measure the CTOD at locations other than the center of the crack, the authors propose a technique based on full field three-dimensional profile measurement of the notched surface by means of stereoscopic Digital Image Correlation (3D-DIC). The method is based on the plastic hinge model assuming that the crack flanks rotate in a rigid manner around a plastic hinge point in the un-cracked ligament. Having measured full-field out-of-plane displacement at the surface of the specimen around the crack using the 3D-DIC method, CTOD can be inferred over the entire crack front. Results show that, due to the acceptable agreement between the DIC based calculation and CTOD measured from cast replicas, the proposed technique has a sufficient accuracy to measure CTOD on the entire crack front in plastically deforming specimens. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1330 KiB

Open AccessProceeding Paper

Investigating Hydrofracture Evolution of Quasi-Brittle Material Using a Post-Peak Control Technique Associated with Speckle-Shearing Interferometry

by Wei-Chih Chen, Li-Hsien Chen, Shyh-Tsong Lin and Yao-Chung Chen

Proceedings 2018, 2(8), 452; https://doi.org/10.3390/ICEM18-05326 - 12 Jun 2018

Cited by 1 | Viewed by 1431

This paper presents the experimental results obtained with a post-peak loading device of hydraulic fracture controlled by setting circumferential deformation of a specimen to be a closed-loop feedback signal during servo-water-driven and monitored with the optical technique of speckle-shearing interferometry (SSI). The macro-scale [...] Read more.

This paper presents the experimental results obtained with a post-peak loading device of hydraulic fracture controlled by setting circumferential deformation of a specimen to be a closed-loop feedback signal during servo-water-driven and monitored with the optical technique of speckle-shearing interferometry (SSI). The macro-scale complete loading curve obtained by the post-peak loading system indicate the stiffness, peak strength and post-peak behavior of quasi-brittle material subjected to borehole water pressure. The micro-scale out-of-plane displacement (OPD) obtained by SSI corresponding to complete loading curve was exhibited where the internal crack tip was located. The complete hydrofracture evolution from displacement continuity to displacement discontinuity was investigated. The test results provide a better understanding of the hydraulic fracture mechanism which is helpful for the development of theoretical and numerical solutions related to hydraulic fractures. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 4211 KiB

Open AccessProceeding Paper

Single-Component Hybrid Simulation Techniques for Validation of Fatigue Models

by Alex Quinlan and Jacob Waldbjørn

Proceedings 2018, 2(8), 453; https://doi.org/10.3390/ICEM18-05328 - 11 Jun 2018

Cited by 1 | Viewed by 1428

Digital Image Correlation (DIC) is used to track the deformation of a cantilever beam at a measurement-point located away from the loading-point. A baseline test is run using the assumption of a linear relationship between the measurement point and the loading point. A [...] Read more.

Digital Image Correlation (DIC) is used to track the deformation of a cantilever beam at a measurement-point located away from the loading-point. A baseline test is run using the assumption of a linear relationship between the measurement point and the loading point. A second test is run that introduces a proportional-integral-derivative (PID) control based on the DIC measurements. This second method showed an improved ability to follow a cyclic command signal, with the X displacement improving from 14.1% to 6.1% error, the Y displacement from 3.8% to 1.25%, and the Z rotation from 3.2% to 2.0%. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 515 KiB

Open AccessProceeding Paper

Experimental Characterization of the Self-Healing Capacity of Cement Based Materials: An Overview

by Liberato Ferrara, Estefania Cuenca Asensio, Francesco Lo Monte, Marta Roig Flores, Mercedes Sanchez Moreno, Didier Snoeck, Tim Van Mullem and Nele De Belie

Proceedings 2018, 2(8), 454; https://doi.org/10.3390/ICEM18-05322 - 11 Jun 2018

Cited by 4 | Viewed by 2182

This paper, prepared in the framework of the COST Action SARCOS WG2 activities (http://www.cost.eu/COST_Actions/ca/CA15202), provides an overview of the main concepts underlying the experimental characterization of the self-sealing capacity of cement-based materials. This effort intends to pave the way towards standardization of such [...] Read more.

This paper, prepared in the framework of the COST Action SARCOS WG2 activities (http://www.cost.eu/COST_Actions/ca/CA15202), provides an overview of the main concepts underlying the experimental characterization of the self-sealing capacity of cement-based materials. This effort intends to pave the way towards standardization of such experimental methods for a comparative assessment of the self-healing capacity of different cement-based materials and of the effectiveness of different techniques, in order to incorporate self-healing concepts and outcomes into durability-based predictive models and design approaches. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1931 KiB

Open AccessProceeding Paper

Laser Ultrasound Flexible System for Non-contact Inspection of Medium Size and Complex Shaped Composite Structures Made of Carbon Fiber Reinforced Polymer

by Jean-François Vandenrijt, Fabian Languy, Cédric Thizy and Marc Georges

Proceedings 2018, 2(8), 455; https://doi.org/10.3390/ICEM18-05377 - 21 Jun 2018

Cited by 2 | Viewed by 2169

We present the development of a contactless laser ultrasound system for nondestructive inspection of CFRP complex structures. Ultrasound are generated by a thermoelastic effect resulting from a green pulsed laser insulating a point of the inspected part. The resulting displacement of the surface [...] Read more.

We present the development of a contactless laser ultrasound system for nondestructive inspection of CFRP complex structures. Ultrasound are generated by a thermoelastic effect resulting from a green pulsed laser insulating a point of the inspected part. The resulting displacement of the surface point is probed by a two-wave mixing based interferometer working in the near infrared. The system is flexible and completely fiber-coupled. It is able to provide C-scans on complex shaped CFRP aeronautical structures. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 692 KiB

Open AccessProceeding Paper

Twisted Fibers Can Have an Adjustable Thermal Expansion

by Donghua Yue and Liming Wei

Proceedings 2018, 2(8), 456; https://doi.org/10.3390/ICEM18-05341 - 13 Jun 2018

Viewed by 1513

In this paper, a device with high accuracy capacitive sensor (with the error of 0.1 micrometer) is constructed to measure the axial thermal expansion coefficent of the twisted carbon fibers and yarns of Kevlar. A theoretical model based on the thermal elasticity and [...] Read more.

In this paper, a device with high accuracy capacitive sensor (with the error of 0.1 micrometer) is constructed to measure the axial thermal expansion coefficent of the twisted carbon fibers and yarns of Kevlar. A theoretical model based on the thermal elasticity and the geometrical features of the twisted structure is also presented to predict the axial expansion coefficient. It is found that the twist angle, diameter and pitch have remarkable influences on the axial thermal expansion coefficients of the twisted carbon fibers and Kevlar strands, and the calculated results are in good agreement with experimental data. We found that, with the increase of the twist angle, the absolute value of the axial thermal expansion coefficient increases. For the Kevlar samples, the expansion coefficient will grow by about 46% when the twist angle increases from 0 to 25 degrees, while the carbon fiber samples will grow by about 72% when the twist angle increases from 0 to 35 degrees. The experimental measurements and the model calculations reveal important properties of the thermal expansion in the twisted structures. Most notably, the expansion of the strand during heating or cooling can be zero when the twist angle is around β = arcsin(αL/αT)^1/2, where β denotes twist angle of the strand and αL, αT are the longitute and the transverse thermal expansion coefficient of the strand, respectively. According to the present experiments and analyses, a method to control the axial thermal expansion coefficient of this new kind of twisted structure is proposed. Moreover, the mechanism of this tunable thermal expansion is discussed. Based on the model, a method that can be used to rectify the thermal expansion properties of the twist structures is established. This may be a new way of fabricating zero expansion composite materials in the future. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2273 KiB

Open AccessProceeding Paper

Optical Infrared Thermography of CFRP with Artificial Defects: Performance of Various Post-Processing Techniques

by Gaétan Poelman, Saeid Hedayatrasa, Joost Segers, Javier Andres Calderon Tellez, Wim Van Paepegem and Mathias Kersemans

Proceedings 2018, 2(8), 457; https://doi.org/10.3390/ICEM18-05358 - 15 Jun 2018

Cited by 4 | Viewed by 2098

This paper treats an experimental study that focusses on optical infrared thermography for non-destructive testing of composites through lock-in and flash excitation. Different fiber reinforced plastics with various artificial defects have been investigated. Three different post-processing techniques are applied, namely fast Fourier transform [...] Read more.

This paper treats an experimental study that focusses on optical infrared thermography for non-destructive testing of composites through lock-in and flash excitation. Different fiber reinforced plastics with various artificial defects have been investigated. Three different post-processing techniques are applied, namely fast Fourier transform (FFT), principal component analysis (PCA) and thermographic signal reconstruction (TSR). A comparison between the different excitation and post-processing methods is performed, and their strengths and weaknesses in detecting artificial defects in composites are evaluated and discussed. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1164 KiB

Open AccessProceeding Paper

Dynamic Displacements Measurement Employing Fringe Projection and Digital Image Correlation

by Luis Felipe-Sesé, Ángel Molina-Viedma, Elías López-Alba and Francisco Díaz

Proceedings 2018, 2(8), 458; https://doi.org/10.3390/ICEM18-05366 - 18 Jun 2018

Cited by 7 | Viewed by 1565

A combination of Fringe Projection (FP) and 2D Digital Image Correlation (2D DIC) using a single camera has been employed to simultaneously measure in-plane and out-of-plane displacements during different dynamic events such an impact and a vibration analysis. This approach has been adopted [...] Read more.

A combination of Fringe Projection (FP) and 2D Digital Image Correlation (2D DIC) using a single camera has been employed to simultaneously measure in-plane and out-of-plane displacements during different dynamic events such an impact and a vibration analysis. This approach has been adopted in the past by several authors, including Mares et al. who highlighted that if a telecentric lens are not employed the combination of both techniques is not straightforward since the in–plane displacements measured with 2D DIC are sensitive to the out-of-plane displacements. Thus, in-plane displacements measured using 2D DIC should be corrected using the out-of-plane displacements inferred using the FP technique. In the current work, an easy method for in-plane displacement correction using Fringe Projection is adopted when measuring the 3D displacements during an impact on an aluminum plate and the vibration of a composite component which have not been studied by other authors previously. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 754 KiB

Open AccessProceeding Paper

Experimental Procedure for Testing Concrete Slabs Under Blast Loading

by Victor Rey, Francisco Gálvez, Rafael Sancho and David A. Cendón

Proceedings 2018, 2(8), 459; https://doi.org/10.3390/ICEM18-05368 - 18 Jun 2018

Cited by 1 | Viewed by 2116

In this paper the pressure waves generated in a test rig previously presented by the authors for the experimental analysis of concrete slabs subjected to blast loading are analysed. To this aim, the concrete samples are replaced by one single aluminium slab instrumented [...] Read more.

In this paper the pressure waves generated in a test rig previously presented by the authors for the experimental analysis of concrete slabs subjected to blast loading are analysed. To this aim, the concrete samples are replaced by one single aluminium slab instrumented with pressure gauges. In order to analyze the experimental scatter, the test set-up is repeated four times, with the only variation of the location of the aluminium slab within the four available positions in the test rig. The pressure histories registered show good agreement with the typical patterns expected in open-air explosions and demonstrates the quasi-planar shape of the pressure wave acting on the slabs. By comparing between the results obtained in different detonations, the explosive charge seems to be among the main sources of experimental scatter in this kind of tests. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1355 KiB

Open AccessProceeding Paper

Application of PVDF Gauges in Solid Interface

by Zhifang Deng, Ruoze Xie, Fangju Zhang and Gang Chen

Proceedings 2018, 2(8), 460; https://doi.org/10.3390/ICEM18-05359 - 15 Jun 2018

Viewed by 1481

It’s difficult to directly measure the pressure on the surface of the material in the impact process. PVDF (Polyvinylidene Fluoride) gauges may help to solve this problem. In this paper, some split Hopkinson pressure bar (SHPB) experiments were carried out with the PVDF [...] Read more.

It’s difficult to directly measure the pressure on the surface of the material in the impact process. PVDF (Polyvinylidene Fluoride) gauges may help to solve this problem. In this paper, some split Hopkinson pressure bar (SHPB) experiments were carried out with the PVDF gauges as specimens, with the strain gauges pasted on the bars being used as the measurement method. By comparing the results of the strain gauges and the PVDF gauges, it is proved that there is a stress concentration when the PVDF gauges were sandwiched directly in the solid interface. Then, two methods to eliminate the stress concentration are verified by experiments. The first method is adding a cushion, such as electrical tape. The second method is using 502 glue, which is evenly coated on the interface. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1107 KiB

Open AccessProceeding Paper

Analysis and Testing of Debris Monitoring Sensors for Aircraft Lubrication Systems

by Etienne Harkemanne, Olivier Berten and Patrick Hendrick

Proceedings 2018, 2(8), 461; https://doi.org/10.3390/ICEM18-05360 - 15 Jun 2018

Cited by 7 | Viewed by 2641

In an aircraft engine, some pieces are describing a rotating movement. These parts are in contact with rotating and non-rotating parts through the bearings and gears. The different contact patches are lubricated with oil. During the lifetime of the engine, mechanical wear is [...] Read more.

In an aircraft engine, some pieces are describing a rotating movement. These parts are in contact with rotating and non-rotating parts through the bearings and gears. The different contact patches are lubricated with oil. During the lifetime of the engine, mechanical wear is produced between the contacts. This wear of the bearings and gears will produce some debris in the oil circuit of the engine. To ensure the effective operation of the aircraft engines, the debris monitoring sensors play a significant role. They detect and collect the debris in the oil. The analysis of the debris can give an indication of the overall health of the engine. The aim of the paper is to develop, design and model an oil test bench to simulate the oil lubrication circuit of an aircraft engine to test two different debris monitoring sensors. The methodology consists of studying the oil lubrication system of the aircraft engine. The first step is to build the oil test bench. Once the oil test bench is functional, tests are performed on the two debris monitoring sensors. A test plan is followed, three sizes of debris, like the type and sizes of debris found in the aircraft engine oil, are injected in the oil. The test parameters are the oil temperature, the oil flow rate and the mass of debris injected. Each time debris is injected, it is detected and caught by the two sensors. The test results given by the two sensors are similar to the mass debris injected into the oil circuit. The two sensors never detect the total mass of debris injected in the oil. On average, 55%–60% of the mass injected is detected and caught by the two sensors. The sensors are very efficient at detecting debris whose size corresponds to the design range parameters of the sensors, but the efficiency falls when detecting debris whose size lies outside this range. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 10882 KiB

Open AccessProceeding Paper

Damage Identification Using Sub-Microstrain FBG Data from a Pre-Stressed Concrete Beam During Progressive Damage Testing

by Dimitrios Anastasopoulos, Maure De Smedt, Guido De Roeck, Lucie Vandewalle and Edwin P. B. Reynders

Proceedings 2018, 2(8), 462; https://doi.org/10.3390/ICEM18-05367 - 18 Jun 2018

Cited by 1 | Viewed by 1515

Vibration-based damage identification can constitute a successful approach for Structural Health Monitoring (SHM) of civil structures. It is a non-destructive condition assessment method, dependent on the identification of changes in the modal characteristics of a structure that are related to damage. However, the [...] Read more.

Vibration-based damage identification can constitute a successful approach for Structural Health Monitoring (SHM) of civil structures. It is a non-destructive condition assessment method, dependent on the identification of changes in the modal characteristics of a structure that are related to damage. However, the damage identification from the modal characteristics of existing structures currently suffers from a low sensitivity of eigenfrequencies and mode shapes to certain types of damage. Furthermore, the sensitivity of eigenfrequencies to environmental influences may be sufficiently high to completely mask the effect even of severe damage. Modal strains and curvatures are more sensitive to local damage, but the direct monitoring of these quantities is challenging when the strain level is very low. In the present work, the identification of the modal strains of a pre-stressed concrete beam, subjected to a progressive damage test, is performed. Dynamic measurements are conducted on the beam at the beginning of each cycle and its response is recorded with multiplexed Fiber-optic Bragg Grating (FBG) strain sensors. Bending, lateral and torsional modes are accurately identified from dynamic strains of the sub-microstrain level. The evolution of the modal characteristics of the beam after each loading cycle is investigated. Changes of the eigenfrequency values, the amplitude and the curvature of the strain mode shapes are observed. The changes in the strain mode shapes appear at the locations where the damage is induced, and are already identified from an early damaged state. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 335 KiB

Open AccessProceeding Paper

Experimental and Numerical Analysis of Timber I-Joists with Cut-Outs

by Rik Steensels and Bram Vandoren

Proceedings 2018, 2(8), 463; https://doi.org/10.3390/ICEM18-05375 - 20 Jun 2018

Cited by 1 | Viewed by 1648

This contribution presents the results of an experimental and numerical campaign evaluating the influence of cut-outs on the strength and stiffness of composite timber I-joists. These cut-outs are often introduced in the webs during the instalment of utility lines. The presence of these [...] Read more.

This contribution presents the results of an experimental and numerical campaign evaluating the influence of cut-outs on the strength and stiffness of composite timber I-joists. These cut-outs are often introduced in the webs during the instalment of utility lines. The presence of these cut-outs will have an impact on the structural behaviour of the element. However, these influences are not taken into account in the current design standards. In order to evaluate the impact of the cut-outs, an experimental campaign was set up in which the structural behaviour of seven composite I-joist beam was analysed. The geometry and spacing of the cut-outs were varied along these seven beam elements. The experimental results clearly show the reduction in stiffness and the influence on the failure mechanism of the beam elements caused by the cut-outs. Additional to the experimental study, a numerical campaign in which the structural response of these I-joists is modelled is also performed. Nonlinear material behaviour is taken into account in the numerical models through the use of a gradient-enhanced damage model. Overall, good agreement is reached between the experimental and numerical data for the beam elements in the linear elastic regime. The ultimate load was also represented well by the numerical model for those elements which fail due to failure of the hardboard web. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1225 KiB

Open AccessProceeding Paper

A New Experimental Test for the Characterisation of Masonry Shear Parameters

by Nicola Viale and Giulio Ventura

Proceedings 2018, 2(8), 464; https://doi.org/10.3390/ICEM18-05369 - 18 Jun 2018

Cited by 2 | Viewed by 1580

The shear properties evaluation on existing unreinforced masonry structure is usually performed through destructive tests. However, these tests have the characteristics of being very expensive and result in significant damage, not only to the samples but also on the portion of wall surrounding [...] Read more.

The shear properties evaluation on existing unreinforced masonry structure is usually performed through destructive tests. However, these tests have the characteristics of being very expensive and result in significant damage, not only to the samples but also on the portion of wall surrounding them. The present work illustrates the design of a new testing procedure for the characterisation of the shear properties in masonry panels for application in routine testing. In the aim of preserving the integrity of the area under testing, and to reduce the cost of the new testing procedure, it has been decided to use flat jacks. The numerical analyses used to design the test are presented, as well as the results of a first application of the procedure. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 428 KiB

Open AccessProceeding Paper

Shape-Changing Carbon Fiber Composite with Tunable Frequency and Damping

by Arnaldo Casalotti and Giulia Lanzara

Proceedings 2018, 2(8), 465; https://doi.org/10.3390/ICEM18-05382 - 21 Jun 2018

Cited by 1 | Viewed by 1452

A shape-adaptable Carbon Fiber Reinforced Composite (CFRC) is proposed to derive a material with tunable mechanical properties in order to optimize its response to external excitations. The composite is bi-stable thanks to internal stresses arising in the manufacturing process and is characterized by [...] Read more.

A shape-adaptable Carbon Fiber Reinforced Composite (CFRC) is proposed to derive a material with tunable mechanical properties in order to optimize its response to external excitations. The composite is bi-stable thanks to internal stresses arising in the manufacturing process and is characterized by a built-in heating system that can control the temperature of the material. This approach allows to gradually change the actual curvature of the material as well as tuning its natural frequencies and damping properties. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 357 KiB

Open AccessProceeding Paper

Highly Performing Nanocomposite Sensors for Damage Detection

by Erika Magnafico, Maryam Karimzadeh and Giulia Lanzara

Proceedings 2018, 2(8), 466; https://doi.org/10.3390/ICEM18-05376 - 20 Jun 2018

Viewed by 1245

Due to their superior physical and electro-mechanical properties, Carbon Nanotubes (CNTs) are one of the most promising composite fillers to realize ultralight and flexible strain sensors that can be used, among others, to monitor strain concentrations within a structure when damage occurs. In [...] Read more.

Due to their superior physical and electro-mechanical properties, Carbon Nanotubes (CNTs) are one of the most promising composite fillers to realize ultralight and flexible strain sensors that can be used, among others, to monitor strain concentrations within a structure when damage occurs. In this study, sensors are made of Multi-walled Carbon Nanotubes (MWNTs) embedded in a Polymide (PI) matrix. Nanocomposites are characterized under no-load conditions to study the electrical properties, and under tensile loading conditions, to evaluate the electromechanical and piezoresistive response. The results highlight a two orders of magnitude decrease in electrical resistivity if compared with previous studies, the capability to instantaneously respond to unpredictable deformations and to easily adapt to three-dimensional shapes. The beauty of the as conceived nanocomposite film, if compared with the commercially available strain gages, is its unprecedented potential expandability to monitor larger areas without the loss of ultra-low local (in scale) detection. Local detection is in fact allowed by nanoscale morphology changes that induce changes in local electrical conduction. The selected polyimide matrix allows the use of the proposed sensor to harsh and high temperature environments while keeping high flexibility and excellent mechanical properties, key parameters for the realization of reliable electromechanical films. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1457 KiB

Open AccessProceeding Paper

Continuous Monitoring the Cathedral of Milan: Design, Installation and Preliminary Results

by Carmelo Gentile and Francesco Canali

Proceedings 2018, 2(8), 467; https://doi.org/10.3390/ICEM18-05354 - 14 Jun 2018

Cited by 2 | Viewed by 3718

The Milan Cathedral, built between 1386 and 1813, is one of the largest masonry monuments ever built. After a brief description of the Cathedral, the paper presents the conceptual design of the monitoring system aimed at assisting the condition-based structural maintenance of the [...] Read more.

The Milan Cathedral, built between 1386 and 1813, is one of the largest masonry monuments ever built. After a brief description of the Cathedral, the paper presents the conceptual design of the monitoring system aimed at assisting the condition-based structural maintenance of the historic building. To the authors’ knowledge, the presented monitoring system is the largest ever implemented in a Cultural Heritage monument; in addition, appropriate strategies of Structural Health Monitoring have been developed for the continuous interrogation of sensors installed in the structure and the extraction from measured data of features which are representative of the current state of structural health. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 602 KiB

Open AccessProceeding Paper

Calibration of Hardness Transfer Functions Based on Micro Tensile and All Weld Metal Tensile Tests of Heterogeneous Welds

by Sameera Naib, Primož Štefane, Wim De Waele, Nenad Gubeljak and Stijn Hertelé

Proceedings 2018, 2(8), 468; https://doi.org/10.3390/ICEM18-05372 - 19 Jun 2018

Cited by 1 | Viewed by 1803

In order to assess the integrity of welded structures, it is important to accurately know the material characteristics of the weld regions. A weldment is heterogeneous i.e., strength properties vary at different locations within the weld. This influences the behavior of the structure [...] Read more.

In order to assess the integrity of welded structures, it is important to accurately know the material characteristics of the weld regions. A weldment is heterogeneous i.e., strength properties vary at different locations within the weld. This influences the behavior of the structure when it is subjected to loading. Hence, the evaluation of material properties within the weld region plays a pivotal role in structural integrity assessment. Traditionally, tensile tests provide constitutive properties like tensile strength and yield strength along with stress (σ)—strain (ε) curves. Alternatively, hardness indentations are also used to procure strength properties of a material. Several transfer functions have been formulated to convert hardness values to strength properties. The validity of these transfer functions with the presence of strength variations is questionable, as these relations do not consider the aspect of heterogeneity. Accordingly, in this research, a heterogeneous weld was considered to assess the relation between Vickers hardness (HV5) and strength properties. Two tensile test configurations were considered—All Weld Metal Tensile Tests (AWMTT) and Micro Tensile Tests (MTT). While AWMTT provides average weld stress-strain properties, MTT provide local properties. These results help to validate the hardness transfer functions and thus calibrate them appropriately. Hardness maps were obtained on polished weld macrographs. The material properties obtained from three methods were compared and significant variations were observed. Based on these differences, an experimentally calibrated transfer function is implemented. With this relation, it is possible to predict weld behavior more accurately and appropriately using hardness maps and tensile tests. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 483 KiB

Open AccessProceeding Paper

Pin-on-Plate Abrasive Wear Test for Several Composite Materials

by Hasan Muhandes, Gábor Kalácska, Nawar Kadi and Mikael Skrifvars

Proceedings 2018, 2(8), 469; https://doi.org/10.3390/ICEM18-05333 - 12 Jun 2018

Cited by 3 | Viewed by 2374

Friction which happens between plants and soil particles with the agricultural machine parts leads to substantial losses due to wear these parts. Nowadays, polymer matrix composites are playing a great role as a replacement of some critical fast-wearing steel due to their high [...] Read more.

Friction which happens between plants and soil particles with the agricultural machine parts leads to substantial losses due to wear these parts. Nowadays, polymer matrix composites are playing a great role as a replacement of some critical fast-wearing steel due to their high properties, and this replacement leads to increase the machine reliability besides better corrosion resistance and lighter construction. Five types of composite materials were suggested to replace these steel parts. We chose ESD PA6 G, HD1000, PA6E, PA6G and PA66GF30 as test materials. And two kinds of testing methods were done to test these materials. First one is a pin-on-plate test with sliding abrasive clothes, the second one is a sand slurry test which uses standard abrasive particles. In the pin-on-plate abrasive wear system, we found that PA6G was the best choice of the used polymers because it had the lowest wear rate. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 4805 KiB

Open AccessProceeding Paper

Influence of Micro-Structure on the Fatigue Crack Propagation in Bridge Steel

by Stanislav Seitl, Petr Miarka, Pavel Pokorný, Stanislava Fintová and Jan Klusák

Proceedings 2018, 2(8), 470; https://doi.org/10.3390/ICEM18-05373 - 19 Jun 2018

Cited by 2 | Viewed by 1871

The use of high strength steels (HSS) allows designing lighter, slenderer and simpler structures with high structural performance. In general, the use of HSS leads to weight reduction of the whole structure, which compensates the higher cost of such a material comparing to [...] Read more.

The use of high strength steels (HSS) allows designing lighter, slenderer and simpler structures with high structural performance. In general, the use of HSS leads to weight reduction of the whole structure, which compensates the higher cost of such a material comparing to the conventional construction steels. Knowledge of the fatigue resistance of material plays the key role during design and maintenance of the bridge structures. This contribution brings a comparison of the fatigue crack growth resistance of S355 J0 steel. Differences in microstructure and the texture of material structure could generally play a role in the fatigue crack growth. This study shows that in the case of studied steel texture of material structure has an influence on material fatigue behavior in Paris’ law regime. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 584 KiB

Open AccessProceeding Paper

Experimental Measurement of Pressure Loading from Near-Field Blast Events: Techniques, Findings and Future Challenges

by Andrew Tyas

Proceedings 2018, 2(8), 471; https://doi.org/10.3390/ICEM18-05364 - 18 Jun 2018

Cited by 6 | Viewed by 2397

The accurate characterisation of pressure loads imposed on structural members following the detonation of a high explosive is critical to our ability to design protective systems. This poses serious challenges for experimentalists, due to the high magnitude and short duration of loading. If [...] Read more.

The accurate characterisation of pressure loads imposed on structural members following the detonation of a high explosive is critical to our ability to design protective systems. This poses serious challenges for experimentalists, due to the high magnitude and short duration of loading. If the distance from the detonation to the target is relatively large, the loading is imparted through the interaction of a shock wave travelling away from the detonation through the surrounding medium, say air. Here, pressure magnitudes are typically in the range 10³–10⁶Pa and are measurable using conventional, commercially available piezo-electric or piezo-resistive pressure transducers. A considerable effort has been expended on experimentally characterizing these “far-field” loads and consequently, we have a strong understanding of the mechanisms and magnitudes of loading. However, we are also interested in the loading when the target is very close to the detonation, for a range of protection applications, from aviation security to the design of personnel protection. Here, very different physical processes dominate. At these so-called “near-field” distances from a detonation (<~1 m/kg_TNT^1/3) the high temperature gaseous detonation products are still violently expanding, and loading on a target is generated by the impingement of both the shocked surrounding material and these products themselves. Blast pressures are often higher that the yield strength of structural materials and temperatures can reach several thousand Kelvin. Furthermore, loading can vary by an order of magnitude over very short distances and timescales. This paper will describe experimental work conducted at University of Sheffield on developing approaches to accurately measure and predict near-field blast loading and gain a better understanding of the underlying mechanisms of loading. The challenges inherent to this field of work will be discussed and an attempt made to identify some of the emerging themes for future research. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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4 pages, 1863 KiB

Open AccessProceeding Paper

PCB Tests during Assembly and Splitting

by Jan Chvojan

Proceedings 2018, 2(8), 472; https://doi.org/10.3390/ICEM18-05365 - 18 Jun 2018

Cited by 1 | Viewed by 1997

The flexure inspection of printed circuit boards during assembly and operation is the object of the article. The goal is to identify high stresses which can lead to destruct especially the soldered connections during final product operation using strain gauge technique. This is [...] Read more.

The flexure inspection of printed circuit boards during assembly and operation is the object of the article. The goal is to identify high stresses which can lead to destruct especially the soldered connections during final product operation using strain gauge technique. This is demonstrated on some examples. It is shown how important is the proper wires installation leading from strain gauges to measurement unit. The tests are performed according IPC guidelines but some remarks are given to guidelines specification. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 4672 KiB

Open AccessProceeding Paper

Digital Image Correlation to Investigate Crack Propagation and Healing of Asphalt Concrete

by Navid Hasheminejad, Alexandros Margaritis, Bart Ribbens, Cedric Vuye, Johan Blom, Wim Van den Bergh, Joris Dirckx and Steve Vanlanduit

Proceedings 2018, 2(8), 473; https://doi.org/10.3390/ICEM18-05381 - 21 Jun 2018

Cited by 1 | Viewed by 1798

Accurate determination of the mechanical properties of asphalt concrete is very important in Road Engineering. The traditional method to calculate these properties is to run experiments using a hydraulic/pneumatic actuator and strain gauges to apply stress and measure the strain. However, in the [...] Read more.

Accurate determination of the mechanical properties of asphalt concrete is very important in Road Engineering. The traditional method to calculate these properties is to run experiments using a hydraulic/pneumatic actuator and strain gauges to apply stress and measure the strain. However, in the last decade optical measurement techniques have become popular for strain calculation on the surface of the specimen and detecting the cracks on the surface. In this study, digital image correlation is used to estimate the strain map on the surface of an asphalt specimen, predict the location of crack initiation, and investigate the healing phenomenon in asphalt concrete. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1389 KiB

Open AccessProceeding Paper

Fatigue of Additive Manufacturing Specimens: A Comparison with Casting Processes

by Eric Charkaluk and Victor Chastand

Proceedings 2018, 2(8), 474; https://doi.org/10.3390/ICEM18-05352 - 14 Jun 2018

Cited by 6 | Viewed by 2314

In this paper, the specificity and/or the common features of materials coming from such new additive manufacturing processes will be compared to more classical one, like casting process. Fatigue properties of Ti-6Al-4V specimens built by EBM and SLM are first compared depending on [...] Read more.

In this paper, the specificity and/or the common features of materials coming from such new additive manufacturing processes will be compared to more classical one, like casting process. Fatigue properties of Ti-6Al-4V specimens built by EBM and SLM are first compared depending on several process parameters. Then, at the microstructure scale, it is shown that surface defects and unmelted zones seem to be the dominant features. It will be shown that similarities can then be drawn with casting processes where shrinkage and pores are also associated to damage mechanisms. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 379 KiB

Open AccessProceeding Paper

Geothermal Well Casings Used as Electrodes in a Resistivity Study at Reykjanes Reservoir in Iceland

by Lilja Magnusdottir and Magnus T. Jonsson

Proceedings 2018, 2(8), 475; https://doi.org/10.3390/ICEM18-05383 - 21 Jun 2018

Cited by 1 | Viewed by 1398

Direct current resistivity measurements are performed at Reykjanes geothermal reservoir in southwest Iceland to investigate the possibility of using steel casings as electrodes to transfer electric current deep into the ground during cross-well resistivity surveys. Various wells are studied including well IDDP-2 that [...] Read more.

Direct current resistivity measurements are performed at Reykjanes geothermal reservoir in southwest Iceland to investigate the possibility of using steel casings as electrodes to transfer electric current deep into the ground during cross-well resistivity surveys. Various wells are studied including well IDDP-2 that has been deepened by the Iceland Deep Drilling Project (IDDP) to a depth of 4.7 km. Electrical resistance measured between two well casings is compared to the resistance between a well casing and an electrode on the surface. The results indicate that the current travels deeper into the ground and through water channels from one casing to another when using the well casings as electrodes instead of traveling closer to the surface as when surface electrodes are used. Steel casings provide good conduction into the ground in resistivity studies and cross-well resistivity measurements can be used to gain information about the subsurface such as the fracture connectivity between wells. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 3332 KiB

Open AccessProceeding Paper

Analytical Calculation of Load Tests of Curved Ceiling Elements Made of Carbon Concrete and Nonwovens Impregnated with Concrete

by Tilo Senckpiel and Ulrich Häußler-Combe

Proceedings 2018, 2(8), 476; https://doi.org/10.3390/ICEM18-05357 - 15 Jun 2018

Viewed by 2194

Carbon reinforced concrete (in short: carbon concrete) allows thin cross sections and lightweight, high-strength structures. This is demonstrated in this article using the example of a lightweight, prefabricated ceiling girder. In addition to the new building material carbon concrete, another innovative cement-bonded composite [...] Read more.

Carbon reinforced concrete (in short: carbon concrete) allows thin cross sections and lightweight, high-strength structures. This is demonstrated in this article using the example of a lightweight, prefabricated ceiling girder. In addition to the new building material carbon concrete, another innovative cement-bonded composite material is used: concrete-impregnated nonwovens. The ceiling element is a very light, slim construction that is curved in the transverse direction. In addition to the material and construction, the article describes the experimental investigation and the possibility of calculation using an analytical approach. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 727 KiB

Open AccessProceeding Paper

A Source Localization Technique Based on a Ray-Trace Technique with Optimized Resolution and Limited Computational Costs

by Yoshikazu Kobayashi, Kenichi Oda and Katsuya Nakamura

Proceedings 2018, 2(8), 477; https://doi.org/10.3390/ICEM18-05380 - 21 Jun 2018

Cited by 1 | Viewed by 1697

A new source localization technique is proposed in this study. The proposed source localization technique considers heterogeneity of elastic wave velocity distribution that is generally caused by local deteriorations or damages of structures on the basis of ray-trace technique. Resolutions of identified source [...] Read more.

A new source localization technique is proposed in this study. The proposed source localization technique considers heterogeneity of elastic wave velocity distribution that is generally caused by local deteriorations or damages of structures on the basis of ray-trace technique. Resolutions of identified source locations are raised by installing extra source candidates near a roughly identified source location with a half of an interval of nodal and relay points in the technique. Further, the extra source candidates are installed in the vicinity of the identified source locations with a half of the previous interval, and source locations are identified again. The resolution consequently rises up to the requirement with limited computational cost by performing the procedure iteratively in the proposed technique. A series of numerical investigations were performed for verification of the proposed technique, and it was confirmed that the proposed technique identified the source locations in required resolution in a limited computational cost. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 1979 KiB

Open AccessProceeding Paper

Delaying Effect of Fatigue Crack Propagation by Single-Pulse Laser Irradiation

by Masayuki Arai, Kenji Inada, Tomoki Morinaga, Kiyohiro Itoh, Hiroki Yokota and Tatsuo Suidzu

Proceedings 2018, 2(8), 478; https://doi.org/10.3390/ICEM18-05334 - 12 Jun 2018

Cited by 1 | Viewed by 1584

In this study, a single-pulse laser technique was applied to repair the cracked plate. The idea of this technique is based on delaying fatigue crack propagation by irradiating the area ahead of the crack tip by using a single-pulse laser with a high [...] Read more.

In this study, a single-pulse laser technique was applied to repair the cracked plate. The idea of this technique is based on delaying fatigue crack propagation by irradiating the area ahead of the crack tip by using a single-pulse laser with a high power of 1500 W. In order to verify the capability of this technique, fatigue tests were conducted on specimens with a hole on the center to induce fatigue cracks at the edge of the hole. A single-pulse laser irradiation was then applied ahead of this natural crack tip, and fatigue tests were subsequently conducted. The fatigue crack propagation behavior was monitored during cycling loading by using a digital microscope. It was confirmed that the crack irradiated by a pulse-laser is not almost progressed or is deflected around the irradiated area in subsequent cyclic loading after the repairing treatment, which means that the pulse laser technique could be located as an alternative to existing repairing techniques. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 735 KiB

Open AccessProceeding Paper

Repeated Loading of Cement Composite Sandwich Beams

by Matthias De Munck, Jolien Vervloet, Michael El Kadi, Svetlana Verbruggen, Jan Wastiels, Tine Tysmans and Olivier Remy

Proceedings 2018, 2(8), 479; https://doi.org/10.3390/ICEM18-05353 - 14 Jun 2018

Viewed by 1377

Using large lightweight prefabricated sandwich panels offers great possibilities for the renovation of existing dwellings. By facilitating the installation process it reduces the total renovation time to a couple of days. During their life-time, these panels will be subjected to wind loading, equivalent [...] Read more.

Using large lightweight prefabricated sandwich panels offers great possibilities for the renovation of existing dwellings. By facilitating the installation process it reduces the total renovation time to a couple of days. During their life-time, these panels will be subjected to wind loading, equivalent to a repeated loading. The effect of this loading condition on the structural behavior of the sandwich panels was verified experimentally. Four-point bending tests were conducted, both static and cyclic. Results showed that the subjection to different loading-unloading cycles resulted in a residual deformation and a decreased stiffness. After being subjected to a repeated loading, the residual ultimate capacity was lowered with 30%. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1764 KiB

Open AccessProceeding Paper

Assessment of Damage Distribution in Brittle Materials by Application of an Improved Algorithm for Three-Dimensional Localization of Acoustic Emission Sources with P-Wave Velocity Calculation

by Patricia Rodríguez and Tarcisio B. Celestino

Proceedings 2018, 2(8), 480; https://doi.org/10.3390/ICEM18-05363 - 18 Jun 2018

Viewed by 1586

The rupture process in brittle materials is associated with tensile stresses at microscopic flaw scale inside their volume. Acoustic emission monitoring of diametral compression tests is an adequate option to assess the progression of damage. An improved algorithm for AE sources localization with [...] Read more.

The rupture process in brittle materials is associated with tensile stresses at microscopic flaw scale inside their volume. Acoustic emission monitoring of diametral compression tests is an adequate option to assess the progression of damage. An improved algorithm for AE sources localization with P-wave velocity, v_p, calculation and an enhanced methodology for P-wave onset time, called CLAPWaVe (Rodríguez 2015), is applied to analyze the distribution of damage and the evolution of stiffness within monzogranite specimens. Complementary analyses allowed the identification of four zones of damage accumulation within the specimen volume, each of them with different cracking levels, absolute energy release, E_A, associated v_p values, induced by different phenomena occurring during the loading process. The observed non-homogeneous damage distribution confirms that using a unique v_p value to perform the localization of all AE sources, as usually adopted, is not representative of the real condition of the specimen. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 381 KiB

Open AccessProceeding Paper

Thermography and Shearography Inspection of Composite Hybrid Sandwich Structure Made of CFRP and GFRP Core and Titanium Skins

by Marc Georges, Christian Srajbr, Philipp Menner, Joachim Koch and Alexander Dillenz

Proceedings 2018, 2(8), 484; https://doi.org/10.3390/ICEM18-05384 - 22 Jun 2018

Cited by 4 | Viewed by 2106

We have investigated several full-field contactless techniques, such as thermography and shearography, with several excitation methods for inspecting hybrid composite-metal sandwich structures. The latter are made of a core with epoxy reinforced by carbon and glass fibers and skins of titanium. Several calibrated [...] Read more.

We have investigated several full-field contactless techniques, such as thermography and shearography, with several excitation methods for inspecting hybrid composite-metal sandwich structures. The latter are made of a core with epoxy reinforced by carbon and glass fibers and skins of titanium. Several calibrated defects are incorporated at different places in depth and are made of air gaps and inserts. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 3101 KiB

Open AccessProceeding Paper

Evaluation of Fracture Process in Concrete by Means of Acoustic Approaches

by Tomoki Shiotani, Hisafumi Asaue, Katsufumi Hashimoto and Takahiro Nisahida

Proceedings 2018, 2(8), 485; https://doi.org/10.3390/ICEM18-05388 - 26 Jun 2018

Viewed by 1403

Through the life cycle of civil infrastructures, quality assessments shall be implemented when construction, in-service, before/after repair and so forth; however, there are no decisive techniques to evaluate inside of structures non-destructively. The authors have developed an advanced measurement method using tomographic approaches. [...] Read more.

Through the life cycle of civil infrastructures, quality assessments shall be implemented when construction, in-service, before/after repair and so forth; however, there are no decisive techniques to evaluate inside of structures non-destructively. The authors have developed an advanced measurement method using tomographic approaches. With these advanced technologies, internal damage or defects can be visualized as a distribution of elastic wave parameters such as velocities so that damage identification consisting of locations and damage degree would be possible. In the paper, fracture processes of concrete decks are visualized by the acoustic approaches. Specifically, RC slabs with/without water supply subject to wheel loads are cyclically damaged with monitoring acoustic approaches. As a result, depending on the water condition, different pattern of fracture progress can be confirmed. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 337 KiB

Open AccessProceeding Paper

Auxetic Films with a Miniaturized Cellular Structure

by Yingjie Chen and Giulia Lanzara

Proceedings 2018, 2(8), 486; https://doi.org/10.3390/ICEM18-05390 - 28 Jun 2018

Viewed by 1383

Auxetic materials represent a relatively new class of materials that are characterized by a cellular structure and a negative Poisson coefficient. Auxetics are extremely useful for morphing applications thanks to their synclastic deformation capability. Most of these materials have been developed with macro-scaled [...] Read more.

Auxetic materials represent a relatively new class of materials that are characterized by a cellular structure and a negative Poisson coefficient. Auxetics are extremely useful for morphing applications thanks to their synclastic deformation capability. Most of these materials have been developed with macro-scaled cellular units. However there are some applications (e.g., micro-air vehicles or biomedical applications) for which polymeric morphing materials need to be applied in relatively small areas. In these cases, a material scale reduction that leads to lightweight auxetic films with a miniaturized cellular structure could be of great interest. With this in mind, an experimental study was conducted to analyze the response of films that are characterized by a miniaturized cellular structure. The unit cells in this study were made of an aggregation of microwires and micronodes that were strategically interconnected to form auxetic expansions and contractions. The reduction in scale of the cellular units has a significant impact on the material characterization and properties. The response of polymeric micro-scaled cells is in fact here demonstrated to be strongly influenced by surface forces and dramatic changes in gaseous or liquid environment. This represents the most critical aspect and key variation when comparing these films with standard macro-auxetics. The extremely challenging (at this length-scale) fabrication and testing processes were optimized. Single cells, were thus successfully tested in different environments with programmed and digital micro-stages while being monitored under a microscope with a video camera. Digital image correlation techniques were used to highlight the deformation. The expansion/contraction process was found to be fully reversible after several cycles and at different deformation speeds. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1181 KiB

Open AccessProceeding Paper

Efficiency of High Altitude On-shore Wind Turbines: Air Density and Turbulence Effects—Qollpana Wind Farm (Bolivia)

by Rober Mamani, Norbert Hackenberg and Patrick Hendrick

Proceedings 2018, 2(8), 487; https://doi.org/10.3390/ICEM18-05385 - 24 Jun 2018

Cited by 9 | Viewed by 2178

The wind energy is one of the most important alternatives for renewable and clean electricity generation. During the last decade the number of wind farms has largely increased in South America. Qollpana is only one case of an on-shore wind farm but it [...] Read more.

The wind energy is one of the most important alternatives for renewable and clean electricity generation. During the last decade the number of wind farms has largely increased in South America. Qollpana is only one case of an on-shore wind farm but it is located at 2900 m above sea level over a complex terrain. Due to high altitude, the air density is reduced by 27% compared with sea level and the topographic characteristics induce a high level of turbulence. Qollpana wind farm has ten wind turbines reaching 27 MW of installed capacity. October is the month of highest wind average velocity and February with the lowest one. This work analyses the capacity factor of the wind farm, also the air density and the turbulence effects on wind turbine efficiency. The main results show that monthly capacity factor varies between 0.08 and 0.67 in the wind farm. Moreover, the results have shown a considerable effect of the turbulence intensity on the turbines efficiency. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 6915 KiB

Open AccessProceeding Paper

A New Granular Column Collapse Device to Characterise Flowability of Bulk Materials

by Joel Torres-Serra, Enrique Romero and Antonio Rodríguez-Ferran

Proceedings 2018, 2(8), 488; https://doi.org/10.3390/ICEM18-05389 - 26 Jun 2018

Cited by 1 | Viewed by 1886

A wide range of bulk materials with different physical properties are nowadays handled in the packaging industry using different material conveying techniques. Nevertheless, experimental methodologies to characterise flowability of granular materials in actual handling conditions are still under development. This paper presents a [...] Read more.

A wide range of bulk materials with different physical properties are nowadays handled in the packaging industry using different material conveying techniques. Nevertheless, experimental methodologies to characterise flowability of granular materials in actual handling conditions are still under development. This paper presents a new fully instrumented device for flowability assessment by granular column collapse of bulk materials. The generated granular flow is monitored by load cells that register the flow heights and by a high-speed video camera that captures the bulk flow kinematics through particle image velocimetry analysis. The 3D surface morphology of the final condition is determined with a 2D laser profile scanner. Results show the effect of varying the initial column aspect ratio on flow response. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 467 KiB

Open AccessProceeding Paper

Concrete Cracks Detection Based on Deep Learning Image Classification

by Wilson Ricardo Leal da Silva and Diogo Schwerz de Lucena

Proceedings 2018, 2(8), 489; https://doi.org/10.3390/ICEM18-05387 - 24 Jun 2018

Cited by 99 | Viewed by 9808

This work aims at developing a machine learning-based model to detect cracks on concrete surfaces. Such model is intended to increase the level of automation on concrete infrastructure inspection when combined to unmanned aerial vehicles (UAV). The developed crack detection model relies on [...] Read more.

This work aims at developing a machine learning-based model to detect cracks on concrete surfaces. Such model is intended to increase the level of automation on concrete infrastructure inspection when combined to unmanned aerial vehicles (UAV). The developed crack detection model relies on a deep learning convolutional neural network (CNN) image classification algorithm. Provided a relatively heterogeneous dataset, the use of deep learning enables the development of a concrete cracks detection system that can account for several conditions, e.g., different light, surface finish and humidity that a concrete surface might exhibit. These conditions are a limiting factor when working with computer vision systems based on conventional digital image processing methods. For this work, a dataset with 3500 images of concrete surfaces balanced between images with and without cracks was used. This dataset was divided into training and testing data at an 80/20 ratio. Since our dataset is rather small to enable a robust training of a complete deep learning model, a transfer-learning methodology was applied; in particular, the open-source model VGG16 was used as basis for the development of the model. The influence of the model’s parameters such as learning rate, number of nodes in the last fully connected layer and training dataset size were investigated. In each experiment, the model’s accuracy was recorded to identify the best result. For the dataset used in this work, the best experiment yielded a model with accuracy of 92.27%, showcasing the potential of using deep learning for concrete crack detection. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 308 KiB

Open AccessProceeding Paper

Early-Stage Damage Detection in Advanced Multifunctional Aerospace Composites Using Embedded Carbon Nanotubes and Flocked Carbon Fibers

by Latha Nataraj, Michael Coatney, Asha Hall, Mulugeta Haile, Riley Sherman, Jacob O’Donnell and Vijaya Chalivendra

Proceedings 2018, 2(8), 490; https://doi.org/10.3390/ICEM18-05386 - 24 Jun 2018

Viewed by 1611

Early-stage damage detection could provide better reliability and performance and a longer lifetime of materials while reducing maintenance time of a variety of structures and systems. We investigate the early-stage damage formation and damage evolution in advanced multi-functional laminated aerospace composites embedded with [...] Read more.

Early-stage damage detection could provide better reliability and performance and a longer lifetime of materials while reducing maintenance time of a variety of structures and systems. We investigate the early-stage damage formation and damage evolution in advanced multi-functional laminated aerospace composites embedded with a very small amount of carbon nanotubes (CNTs) in the matrix material and short carbon fibers along the Z-direction to reinforce the interlaminar interfaces. The three-dimensional (3-D) conductive network formed by the CNTs and the flocked carbon fibers allows for sensitive in-situ damage detection in materials in addition to providing improved mechanical properties such as superior fracture toughness for damage tolerance. We optimize several parameters such as fiber length, diameter, and density to generate an effective 3-D electrical conductive network, and characterize the responses of these composites under mechanical loading to investigate damage formation and evolution, advancing science and technology towards superior damage-tolerant and zero-maintenance structural materials. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 981 KiB

Open AccessProceeding Paper

Insights into Acoustically Induced PiezoLuminescence: The Visualization of Ultrasonic Beam Patterns

by Simon Michels, Mathias Kersemans, Guillaume Lajoinie, Michel Versluis and Philippe F. Smet

Proceedings 2018, 2(8), 491; https://doi.org/10.3390/ICEM18-05411 - 29 Jun 2018

Viewed by 2096

Ultrasonic transducers are used in many fields of application, including medical imaging/treatment, non-destructive testing and material characterization. To assure the quality of the ultrasonic investigation transducers require regular checks for possible deterioration and accurate calibration. Current methods rely on point-by-point scanning of the [...] Read more.

Ultrasonic transducers are used in many fields of application, including medical imaging/treatment, non-destructive testing and material characterization. To assure the quality of the ultrasonic investigation transducers require regular checks for possible deterioration and accurate calibration. Current methods rely on point-by-point scanning of the ultrasound field with a needle hydrophone, which is expensive and time consuming. Recently, we have developed a new concept, in which a fast full-field visualization of the radiation field is achieved through Acoustically induced PiezoLuminescence (APL). Here, we report on an improved ultrasonic beam visualization and provide further insights into the mechanism underlying APL and mechanoluminescence. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1000 KiB

Open AccessProceeding Paper

Mechanoluminescent Materials: A New Way to Analyze Stress by Light

by Ang Feng, Simon Michels, Alfredo Lamberti and Philippe F. Smet

Proceedings 2018, 2(8), 492; https://doi.org/10.3390/ICEM18-05422 - 30 Jun 2018

Cited by 5 | Viewed by 2488

The monitoring of stress changes in structural components under various kinds of dynamical loading is crucial for the assessment of their integrity and lifetime. In addition to many methodologies available, such as strain gauges, optical fiber sensors, X-Ray diffraction and digital image correlation, [...] Read more.

The monitoring of stress changes in structural components under various kinds of dynamical loading is crucial for the assessment of their integrity and lifetime. In addition to many methodologies available, such as strain gauges, optical fiber sensors, X-Ray diffraction and digital image correlation, we introduce a novel non-contact method to visualize stress distributions based on mechanoluminescence (ML). ML is a phenomenon occurring in some materials that emit light upon an applied stress level. In this paper, we develop the ML material (Ca_0.4Sr_0.6)Al₂Si₂O₈:1%Eu²⁺,1%Ho³⁺, a glow-in-the-dark material, to visualize stress distribution in a disc, as well as the stress field of an ultrasonic transducer. The properties of defects in the ML phosphors, which are responsible for ML in this material, are vital for stress visualization. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 414 KiB

Open AccessProceeding Paper

Dynamic High Pressure Torsion (DHPT)—A Novel Method for High Strain Rate Severe Plastic Deformation

by Harishchandra Lanjewar, Leo Kestens and Patricia Verleysen

Proceedings 2018, 2(8), 493; https://doi.org/10.3390/ICEM18-05399 - 28 Jun 2018

Cited by 3 | Viewed by 1890

Metals with a fine-grained microstructure have exceptional mechanical properties. Severe plastic deformation (SPD) is one of the most successful ways to fabricate ultrafine-grained (UFG) and nanostructured (NC) materials. Most of the SPD techniques employ very low processing speeds. However, the lowest steady-state grain [...] Read more.

Metals with a fine-grained microstructure have exceptional mechanical properties. Severe plastic deformation (SPD) is one of the most successful ways to fabricate ultrafine-grained (UFG) and nanostructured (NC) materials. Most of the SPD techniques employ very low processing speeds. However, the lowest steady-state grain size which can be obtained by SPD is considered to be inversely proportional with the strain rate at which the severe deformation is imposed. In order to overcome this limitation, methods operating at higher rates have been envisaged and used to study the fragmentation process and the properties of the obtained materials. However, almost none of these methods, employ hydrostatic pressures which are needed to prevent the material from failing at high deformation strains. As such, their applicability is limited to materials with a high intrinsic ductility. Additionally, in some methods the microstructural changes are limited to the surface layers of the material. To circumvent these restrictions, a novel facility has been designed and developed which deforms the material at high strain rate under high hydrostatic pressures. Using the facility, commercially pure aluminum was processed and analysis of the deformed material was performed. The microstructure evolution in this material was compared with that observed in static high pressure torsion (HPT) processed material. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 894 KiB

Open AccessProceeding Paper

Enhancement of the Mechanical Performance of Stainless Steel Micro Lattice Structures Using Electroless Plated Nickel Coatings

by Recep Gümrük, Altuğ UŞUN and Robert Mines

Proceedings 2018, 2(8), 494; https://doi.org/10.3390/ICEM18-05403 - 28 Jun 2018

Cited by 1 | Viewed by 2102

The use of nickel electroless plating to enhance the mechanical properties of stainless steel micro lattice structures manufactured using selective laser melting is described. A coating thickness of 17 μm is achieved, and this increases micro lattice specific stiffness by 75% and specific [...] Read more.

The use of nickel electroless plating to enhance the mechanical properties of stainless steel micro lattice structures manufactured using selective laser melting is described. A coating thickness of 17 μm is achieved, and this increases micro lattice specific stiffness by 75% and specific strength by 50%. There is scope for improving the coating process, and hence improving micro lattice mechanical performance. The methodology described here provides a new potential for optimizing micro lattice mechanical performance and can be extended to other cellular materials with different coating technology. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 553 KiB

Open AccessProceeding Paper

Quasi-Static and Dynamic Testing of Annealed Float Glass

by Karoline Osnes, Odd Sture Hopperstad and Tore Børvik

Proceedings 2018, 2(8), 495; https://doi.org/10.3390/ICEM18-05412 - 29 Jun 2018

Cited by 1 | Viewed by 1756

Three different experimental set-ups were employed in the investigation of the fracture strength of annealed float glass. These included four-point bending tests on three different specimen sizes, and quasi-static and dynamic pressure tests. The latter tests were conducted in a shock tube, i.e., [...] Read more.

Three different experimental set-ups were employed in the investigation of the fracture strength of annealed float glass. These included four-point bending tests on three different specimen sizes, and quasi-static and dynamic pressure tests. The latter tests were conducted in a shock tube, i.e., a device that produces pressure loadings similar to that from a far-field blast event. The experimental work demonstrated that the fracture strength of glass varies largely within the same test set-up. It also revealed that the fracture strength and its scatter are dependent on the size of the specimen, the boundary conditions and the loading situation. By employing a newly proposed strength prediction model, which relies on the physical fracture behaviour of glass, the trends observed in the experiments were correctly recreated. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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4 pages, 467 KiB

Open AccessProceeding Paper

Experimental Investigation of the Confined Behavior of Concrete under Shear Loading at High Strain Rates

by Reem Abdul-Rahman, Dominique Saletti and Pascal Forquin

Proceedings 2018, 2(8), 496; https://doi.org/10.3390/ICEM18-05408 - 29 Jun 2018

Viewed by 1428

A new experimental technique has been developed to investigate the confined shear behavior of concrete under dynamic conditions. The technique is based on the ‘Punch through shear test’ and consists in pre-stressing a concrete sample prior to testing it under shear. The pre-confinement [...] Read more.

A new experimental technique has been developed to investigate the confined shear behavior of concrete under dynamic conditions. The technique is based on the ‘Punch through shear test’ and consists in pre-stressing a concrete sample prior to testing it under shear. The pre-confinement is applied by means of a metallic cell instrumented with gages to register the stresses during the test; it consists in deforming the cell with a compressive load and then inserting the specimen into the cell. When the load is released, the cell applies a confinement to the sample. Two notches are performed from each side of the specimen and a displacement is applied to the central part in order to produce shear inside the vertical ligament. Dynamics tests are done with the Split Hopkinson Bar setup where a striker, an incident and two output bars are used. Two sets of specimens have been tested, saturated and dry concrete. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 241 KiB

Open AccessProceeding Paper

Direct Use of Geothermal Resources for Circular Food Production

by Ragnheidur Thorarinsdottir and Runar Unnthorsson

Proceedings 2018, 2(8), 497; https://doi.org/10.3390/ICEM18-05405 - 28 Jun 2018

Cited by 3 | Viewed by 2699

The objectives of the work are to increase the direct use of geothermal resources for circular food production systems. The focus is on circular agricultural production processes: combining recirculating aquaculture systems and hydroponics into one system, including water treatment and waste recovery processes. [...] Read more.

The objectives of the work are to increase the direct use of geothermal resources for circular food production systems. The focus is on circular agricultural production processes: combining recirculating aquaculture systems and hydroponics into one system, including water treatment and waste recovery processes. The main outputs are vegetables, fish, fertilizers and potentially, algae and biogas. These outputs can generate revenue streams that can cover the costs of heat extraction while supporting viable businesses. The results and conclusions from a pilot case that was conducted in Iceland in recent years are presented, and the next steps are discussed. The pilot setup is now in the process of expansion to a semi-commercial production unit. However, there are still scientific, technical and commercial challenges to be solved. The scientific challenges are interdisciplinary and relate mainly to the optimization of the overall production system. Optimization involves creating good environmental conditions for each production unit while maintaining optimal oxygen, carbon dioxide, relevant pH and temperature levels and supplying all necessary nutrients. Additionally, accumulation of salts or other unwanted substances must be prevented. The primary technical challenges are to develop the circular food production system for optimized production while controlling the expenditure of energy, water, nutrients and manpower resources. Optimization also involves careful choices of species and the integration of new ideas into the value chain, both of which increase the synergy between the different components of the system. Furthermore, energy efficiency needs to be improved through using excess heat for other parts of the system and developing enhanced heating and cooling cycles. The aim is to transform the semi-commercial unit into a showcase model for solving commercial challenges while presenting a feasible business model for installing and operating a geothermal well for circular food production, making the most use of all available resources, securing optimum production conditions and minimizing waste. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 1626 KiB

Open AccessProceeding Paper

Small Displacement Measurement of Crack Opening Using One Pitch Phase Analysis (OPPA) Method

by Yoshiharu Morimoto, Akihiro Masaya, Thomas Yata, Duy Anh Luong and Quentin Quarles

Proceedings 2018, 2(8), 498; https://doi.org/10.3390/ICEM18-05407 - 29 Jun 2018

Cited by 1 | Viewed by 1440

A new method to measure small displacement of crack width. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 767 KiB

Open AccessProceeding Paper

Fatigue Performance of Powder Bed Fused Ti-6Al-4V Component with Integrated Chemically Etched Capillary for Structural Health Monitoring Application

by Michaël F. Hinderdael, Dieter De Baere and Patrick Guillaume

Proceedings 2018, 2(8), 499; https://doi.org/10.3390/ICEM18-05419 - 30 Jun 2018

Cited by 6 | Viewed by 1476

Fatigue performance of additively manufactured (AM) components is still uncertain and inconsistent. Structural health monitoring (SHM) systems offer a solution to continuously monitor the structural integrity of a structure. The effective Structural Health Monitoring (eSHM) system is the first SHM principle developed with [...] Read more.

Fatigue performance of additively manufactured (AM) components is still uncertain and inconsistent. Structural health monitoring (SHM) systems offer a solution to continuously monitor the structural integrity of a structure. The effective Structural Health Monitoring (eSHM) system is the first SHM principle developed with the principal purpose to monitor AM components. The eSHM principle exploits the design freedom offered by AM to integrate a capillary inside the component. The capillary is put under low vacuum and the pressure is monitored during the operation of the component. As-built AM surfaces report elevated surface roughness and are one of the principle causes of premature fatigue initiation and fatigue failure. The current study will investigate the effect of a chemical etching (CE) post-process on the capillary surface and evaluate its effect on the fatigue performance. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 435 KiB

Open AccessProceeding Paper

Additive Manufactured Metallic Smart Structures to Monitor the Mechanical Behavior In Situ

by Dieter De Baere, Michaël Hinderdael, Marc Moonens, Zoé Jardon, Margot Lison, Maria Strantza and Patrick Guillaume

Proceedings 2018, 2(8), 500; https://doi.org/10.3390/ICEM18-05425 - 2 Jul 2018

Cited by 2 | Viewed by 1629

Additive manufacturing (AM) has proven in a number of demonstrators its tremendous potential for structural components. AM has gone beyond being a prototyping process and is now firmly being explored as production process in numerous domains. The objective of the paper is to [...] Read more.

Additive manufacturing (AM) has proven in a number of demonstrators its tremendous potential for structural components. AM has gone beyond being a prototyping process and is now firmly being explored as production process in numerous domains. The objective of the paper is to provide an overview of remaining challenges in the field of AM and structural health monitoring. A symbiotic solution, a smart structure, for some of the challenges in both fields will be presented. The development progress made in these domains by the Acoustics and Vibration Research Group (AVRG) of the Vrije Universiteit Brussel will be discussed and the future outlook. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1370 KiB

Open AccessProceeding Paper

Characterization of Electrospun PVDF Fibres for Sensing and Actuation

by Federico Fabriani, Krishna Chinnam Chytanya, Iucci Giovanna and Giulia Lanzara

Proceedings 2018, 2(8), 501; https://doi.org/10.3390/ICEM18-05404 - 28 Jun 2018

Cited by 4 | Viewed by 1931

One of the major challenges for the realization of ultra-light weight and intelligent materials with advanced sensing/actuation capabilities, is related to, among other things, the integration in the material of non-invasive but indeed highly performing sensors and actuators. The reduction in scale, weight, [...] Read more.

One of the major challenges for the realization of ultra-light weight and intelligent materials with advanced sensing/actuation capabilities, is related to, among other things, the integration in the material of non-invasive but indeed highly performing sensors and actuators. The reduction in scale, weight, and flexibility of the sensing devices represents a critical aspect to reach this goal. These unique properties are here reached by using flexible piezoelectric polymer (Polyvinylidene fluoride, PVDF) nanofibers as sensing elements. The nanofibers, that in this case study are randomly distributed, form an ultra-thin nanostructured porous mat that was deposited through a far field electrospinning approach. The process was optimized to obtain a dominant β phase in the polymer to enhance the piezoelectric response. The electrospun fibers were characterized at different scales: at the molecular level to understand the β phase content (FTIR spectroscopy), as well as at the macroscopic level to investigate the resulting ferroelectric and electromechanical response The results presented in this paper show the great capability of the nanostructured porous mat to work as ultra-light weight dynamic sensing system. Its scalable size and intrinsic properties make it an ideal solution for the development of advanced intelligent materials that can work at different length-scales. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 900 KiB

Open AccessProceeding Paper

A Shock Tube Used to Study the Dynamic Response of Blast-Loaded Plates

by Vegard Aune, Folco Casadei, Georgios Valsamos, Magnus Langseth and Tore Børvik

Proceedings 2018, 2(8), 503; https://doi.org/10.3390/ICEM18-05395 - 28 Jun 2018

Cited by 1 | Viewed by 2448

This study aims to a better understanding of the performance of a shock tube used to produce blast loading in controlled laboratory environments. Special focus is placed on the influence of the diaphragm failure process on the blast wave formation in the tube. [...] Read more.

This study aims to a better understanding of the performance of a shock tube used to produce blast loading in controlled laboratory environments. Special focus is placed on the influence of the diaphragm failure process on the blast wave formation in the tube. Experimental observations are supported by numerical simulations in an attempt to obtain more insight into the underlying phenomena. It was found that the diaphragm failure process introduces a multi-dimensional flow field downstream the diaphragms. This is observed as a loss of directional energy in the distant flow field and therefore affects the reflected overpressure on blast-loaded plates located at the rear end of the tube. These findings provide important insight into how such a facility works, especially if the dynamic response of flexible plates is of interest. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1491 KiB

Open AccessProceeding Paper

Identification and Prediction of Mixed-Mode Fatigue Crack Path in High Strength Low Alloy Steel

by Jie Zhang, Cedric Kiekens, Stijn Hertelé and Wim De Waele

Proceedings 2018, 2(8), 504; https://doi.org/10.3390/ICEM18-05420 - 30 Jun 2018

Viewed by 1522

The trajectory of fatigue crack growth is influenced by many parameters and can be irregular due to changes in stress distribution or in material properties as the crack progresses. Images of the surface of a standardized test specimen can be used to visualize [...] Read more.

The trajectory of fatigue crack growth is influenced by many parameters and can be irregular due to changes in stress distribution or in material properties as the crack progresses. Images of the surface of a standardized test specimen can be used to visualize the crack trajectory in a non-destructive way. Accurately identifying the location of the crack tip, however, is challenging and requires devoted image postprocessing. In this respect, digital image correlation allows to obtain full field displacement and strain fields by analysing changes of digital images of the same sample at different stages of loading. This information can be used for the purpose of crack tip tracking. This paper presents a combined experimental-numerical study of detection and prediction of fatigue crack propagation path by means of digital image correlation (DIC) and the extended finite element method (X-FEM). Experimental validation and analyses are carried out on a modified C(T) specimen in which a curved crack trajectory is triggered by introducing mixed-mode (tension + shear) loading. The developed tools are used for validating an automated framework for crack propagation prediction. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1185 KiB

Open AccessProceeding Paper

Modelling Local Bending Stiffness of Norway Spruce Sawn Timber Using Scanned Fibre Orientation

by Min Hu, Anders Olsson, Marie Johansson and Jan Oscarsson

Proceedings 2018, 2(8), 505; https://doi.org/10.3390/ICEM18-05426 - 2 Jul 2018

Viewed by 1492

Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, have been utilized in a previously developed machine strength grading method. [...] Read more.

Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, have been utilized in a previously developed machine strength grading method. However, that method was based on rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections. The purpose of the present study was to suggest and verify a model by which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness variation along boards. Comparisons of results indicated that models suggested herein were sufficient to capture the variation of local bending stiffness along boards with very high accuracy. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 1222 KiB

Open AccessProceeding Paper

In-Situ SEM Deformation Testing of Ni-Based Superalloy Heated by the Joule Heat

by Zhen Wang, Jiecun Liang and Xide Li

Proceedings 2018, 2(8), 507; https://doi.org/10.3390/ICEM18-05415 - 29 Jun 2018

Viewed by 1664

Studying the deformation and microstructure evolution for Ni-based single crystal alloys at high temperature has important effects on the design of turbine blades and disks. However, in-situ high temperature tests under scanning environment pose an important challenge for the current experimental conditions. In [...] Read more.

Studying the deformation and microstructure evolution for Ni-based single crystal alloys at high temperature has important effects on the design of turbine blades and disks. However, in-situ high temperature tests under scanning environment pose an important challenge for the current experimental conditions. In this paper, the resistance heating system was introduced into the high temperature fatigue experimental apparatus. The in-situ tensile test of 900 °C was successfully carried out. The experimental results showed that the crack initiation was mainly caused by inclusion debonding. The fracture mode was mainly characterized by the connection of micro holes. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 556 KiB

Open AccessProceeding Paper

^{Acoustic Emission Health Monitoring of Historical Masonry to Evaluate Structural Integrity under Incremental Cyclic Loading}

by Georgios Livitsanos, Naveen Shetty, Els Verstrynge, Martine Wevers, Danny Van Hemelrijck and Dimitrios G. Aggelis

Proceedings 2018, 2(8), 508; https://doi.org/10.3390/ICEM18-05417 - 30 Jun 2018

Cited by 3 | Viewed by 1645

Historical masonry structures during the decades, were composed with a variety of brick and mortar types according to materials availability of each region and the desirable mechanical properties in each specific case. Different composition of mortars leads to another masonry behavior, and each [...] Read more.

Historical masonry structures during the decades, were composed with a variety of brick and mortar types according to materials availability of each region and the desirable mechanical properties in each specific case. Different composition of mortars leads to another masonry behavior, and each one is suited for different structural purposes. A crucial aspect in damage evaluation of masonry structures is the analysis of long-term behavior which has a great influence on safety assessment of these structures. In this study, cement, hybrid lime cement, hydraulic lime and lime hydrate mortars were assembled with solid red clay bricks to compose four masonry walls of dimensions 515 × 376 × 90 mm. They were tested under cyclic compression loading. Acoustic Emission (AE) allowed in situ monitoring of damage progression. AE is a powerful non-destructive technique applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate a variety of characteristics during fracture propagation to obtain information on the criticality of the ongoing process. Specifically, analyzing and comparing AE parameters among the loading cycles of each wall specimen and among the different masonry compositions, an integrity assessment can be achieved. Furthermore, in each loading and unloading step, pulse velocity measurements were conducted using the AE apparatus in order to gain a velocity distribution mapping among the sensors. Each sensor was pulsed in turn, with all other sensors acting as receivers, generating a velocity matrix from one sensor to another. This provided an insight into the damage severity of masonry walls with the increasing number of loading cycles. This measurement was also necessary for refining AE source location accuracy by using either the horizontal or the vertical velocity. Two different cases were investigated. The use of one uniform velocity for the whole masonry wall and the assumption that the velocity differs in the two vertical directions due to the heterogeneity of the structure. These two cases result in differences in the quantity and the position of the localized events. Furthermore, applying direct ultrasonic pulse velocity measurements, in the direction of the width of masonry walls, another integrity investigation was feasible. The presented results further demonstrate the relationships between AE parameter-based analysis, velocity distribution and source location during cyclic compressive loading in masonry specimens. The identification of the nature of damage through the entire dataset of all sensor arrays provides a promising example for structural health monitoring applications on larger scale masonry specimens. As a conclusion, AE activity analysis proved to be a very efficient approach to evaluate fracture progress in masonry. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 626 KiB

Open AccessProceeding Paper

Dynamic Fracture Process and Strain Rate Effect of a Porous SiC Ceramic

by Yanpei Wang, Ding Zhou, Huifang Liu, Sheikh Muhamamd Zakir and Yulong Li

Proceedings 2018, 2(8), 509; https://doi.org/10.3390/ICEM18-05409 - 29 Jun 2018

Cited by 2 | Viewed by 1705

In this paper, dynamic fracture process and strain rate effect of a porous SiC ceramic were investigated. The failure process under dynamic loading conditions was monitored by a high-speed camera. Digital image correlation (DIC) method was further utilized to calculate the surface strain [...] Read more.

In this paper, dynamic fracture process and strain rate effect of a porous SiC ceramic were investigated. The failure process under dynamic loading conditions was monitored by a high-speed camera. Digital image correlation (DIC) method was further utilized to calculate the surface strain field. The high-speed images show that crack initiates in the center of the specimen and then propagates to the entire specimen under dynamic loading. In addition, DIC result showed that cracks occur on the surface of the specimen formed a band. And the band finally caused the collapse of the specimen. The test results showed that compressive strength of the porous SiC ceramic is rate sensitive. Under quasi-static conditions, the compressive strength is about 120 MPa, while in dynamic conditions strength increased to 247 MPa. Energy absorption during the deformation process is much larger under dynamic loading. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 883 KiB

Open AccessProceeding Paper

Effect of Multi-Impact on QIQH Carbon/Epoxy Composite Laminate

by Adadé Seyth Ezéckiel Amouzou, Olivier Sicot, Ameur Chettah and Shahram Aivazzadeh

Proceedings 2018, 2(8), 511; https://doi.org/10.3390/ICEM18-05400 - 28 Jun 2018

Viewed by 1676

This work is motivated by increasingly used of composite structures under severe loading conditions. During their use, these materials are often subjected to impact as for example, in the aeronautical field the fall of hailstone on structure composites. In fact, the low energy [...] Read more.

This work is motivated by increasingly used of composite structures under severe loading conditions. During their use, these materials are often subjected to impact as for example, in the aeronautical field the fall of hailstone on structure composites. In fact, the low energy traditional impact tests don’t allow to see the evolution of the damage and don’t permit also to compare the best tolerance to impact between different stratifications. The multi-impact tests made it possible to find a solution to this problem. In this work, multi-impact tests are performed on three carbon/epoxy stratifications. The final goal is to predict the durability of the composite structures during impact loading for their design. This study brings to light the response of multi-impact tests through force-time and force-displacement curves obtained experimentally. On the other hand, a parameter D has introduced following the experimental results. This made it possible to rank the three stratifications from their tolerance to multi-impact tests. To evaluate the post impact damage, ultrasonic testing techniques are used. The results allow to find the relationship between the damaged surface obtained by the ultrasonic control and the parameter D and to rank the three laminates configurations. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 617 KiB

Open AccessProceeding Paper

Composite Single-Bolted Joint Simulation for Dynamic Strength Prediction

by Zeliang Yu, Pu Xue and Yue Chen

Proceedings 2018, 2(8), 512; https://doi.org/10.3390/ICEM18-05424 - 2 Jul 2018

Cited by 1 | Viewed by 1642

Composite material has been widely used in various fields for its high specific strength and high specific stiffness, so the connectors applicable to composite structures capture many researchers’ attention. With the advantages of higher carrying capacity and repetitive assembling and disassembling, bolted joint [...] Read more.

Composite material has been widely used in various fields for its high specific strength and high specific stiffness, so the connectors applicable to composite structures capture many researchers’ attention. With the advantages of higher carrying capacity and repetitive assembling and disassembling, bolted joint becomes one of the most popular connectors in engineering practice. Cutting off the fiber and causing stress concentration are more serious to composite than metal, so it is necessary to predict the strength of the composite joints. Most investigations focus on the response under quasi-static loading, while dynamic effects should be in consideration in increasing impact conditions. The dynamic mechanical properties of composite joint may have a significant impact on the structural deformation and damage modes. For this purpose, this paper conducts dynamic composite single-bolted joint simulations in ABAQUS/Explicit, which used for predicting dynamic strength of the composite joint. T800/X850 laminates were tested to investigate their dynamic properties in our lab. Then the three-dimension progression damage model was established, while the dynamic constitutive model, damage initial criteria and damage evolution law of composite materials were coded in VUMAT of the finite element software ABAQUS/Explicit. The model was validated by quasi-static experiments of composite joint. The simulation results indicate that the yield strength and ultimate strength of the single-bolted composite joint are obviously increasing when consider the strain rate effect and dynamic loading. And the load-displacement curves show significant difference in damage stage. The main damages are sub-layer buckling and fiber breakage caused by extrusion. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 378 KiB

Open AccessProceeding Paper

Model Based Bolt Preload Monitoring Using Digital Image Correlation

by Carlos Jiménez-Peña, Alberto Lavatelli, Ruben Balcaen, Barbara Rossi and Dimitri Debruyne

Proceedings 2018, 2(8), 514; https://doi.org/10.3390/ICEM18-05413 - 29 Jun 2018

Cited by 3 | Viewed by 2255

Bolt preload is one of the most significant parameters in bolted connections, which affects the static and fatigue performance of bolted connections. Traditional preload measuring methods give an estimation of the preload at the moment of tightening but cannot monitor preloading losses. In [...] Read more.

Bolt preload is one of the most significant parameters in bolted connections, which affects the static and fatigue performance of bolted connections. Traditional preload measuring methods give an estimation of the preload at the moment of tightening but cannot monitor preloading losses. In this investigation an initial proof of concept of a DIC based approach to relate bolt elongation to bolt preload is presented. Bolt elongation tests were performed to M16 bolts and a calibration method was proposed to obtain the bolt preload-elongation relationship for a given clamping length range. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 863 KiB

Open AccessProceeding Paper

Fast Assessment of Post-Fire Residual Strength of Reinforced Concrete Frame Buildings Based on Non-Destructive Tests

by Pablo Alcaíno, Hernán Santa María, Michael Cortés and Jennyfer Alfaro

Proceedings 2018, 2(8), 515; https://doi.org/10.3390/ICEM18-05394 - 27 Jun 2018

Cited by 1 | Viewed by 1634

Assessment of the residual strength of reinforced concrete buildings subjected to fire is a problem that many times requires a very fast resolution that is necessary for the action of firemen and/or for forensic fire investigation and/or structural assessment of post-fire condition of [...] Read more.

Assessment of the residual strength of reinforced concrete buildings subjected to fire is a problem that many times requires a very fast resolution that is necessary for the action of firemen and/or for forensic fire investigation and/or structural assessment of post-fire condition of the building: in all cases safety and integrity of firemen and researchers can be at risk, and it is necessary to have quick and sufficiently reliable information in order to choose whether enter freely, enter with caution or simply do not enter the burned structure, so there is no time or background to develop mathematical models of damage propagation and/or of the structure. This work presents an experimental methodology for a fast assessment of post-fire residual strength of reinforced concrete frame buildings based on the high correlation between the loss of strength and non-destructive tests results of frame concrete elements subject to fire action. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 495 KiB

Open AccessProceeding Paper

Effect of Malleus Handle Fracture on Middle Ear Sound Transmission: Laser Doppler Vibrometry Measurements and Finite Element Simulations

by Kilian Gladiné, Pieter Muyshondt, Daniël De Greef and Joris Dirckx

Proceedings 2018, 2(8), 516; https://doi.org/10.3390/ICEM18-05423 - 30 Jun 2018

Viewed by 1953

Malleus handle fractures are rare but can cause tremendous hearing loss. Due to the small number of known clinical malleus fracture cases, little is known about the mechanics of middle ears with a malleus fracture. Laser Doppler vibrometry and finite element simulations are [...] Read more.

Malleus handle fractures are rare but can cause tremendous hearing loss. Due to the small number of known clinical malleus fracture cases, little is known about the mechanics of middle ears with a malleus fracture. Laser Doppler vibrometry and finite element simulations are used to gain more knowledge about malleus fractures. The experimental measurements show remarkably that at low frequencies an increase in sound transmission can occur and minimal hearing loss occurs below the intact middle ear resonance frequency due to a resonance shift. The simulations do not show these observations when only a fracture is introduced. The addition of other features possibly related to malleus fractures to the models such as the post-fracture eardrum prestress release improve the simulation results. However, features such as post-fracture eardrum deformation could play an important role too. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 547 KiB

Open AccessProceeding Paper

Analysis of Inclined Cracks in Thin-Walled Circular Tube under Mixed-Mode I + II Fracture

by Boy Raymond Mabuza

Proceedings 2018, 2(8), 517; https://doi.org/10.3390/ICEM18-05421 - 30 Jun 2018

Cited by 1 | Viewed by 1875

This paper provides a study on mixed-mode fracture mechanics in thin-walled tube which is subjected to tension, shear and torsion loading. This type of loading causes an inclined crack to develop and generate a mixture of normal and shear stresses ahead of a [...] Read more.

This paper provides a study on mixed-mode fracture mechanics in thin-walled tube which is subjected to tension, shear and torsion loading. This type of loading causes an inclined crack to develop and generate a mixture of normal and shear stresses ahead of a crack tip. The stress state ahead of a crack tip is frequently based on mixed-mode type of interactions which designate the amplitude of the crack tip stresses. The analytical expressions for the stress intensity factors for mixed-mode I + II approach are presented. The Paris law for mixed-modes I + II has been discussed. Mixed-mode fracture mechanics is used with theoretical models to predict the path of crack growth when an inclined crack is subjected to a combination of mode I and mode II deformations. The torque at which crack propagation can be expected has been determined. The numerical calculations have been carried out by using MATLAB code. The results are good and could be useful for companies working with thin-walled circular tubes. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 840 KiB

Open AccessProceeding Paper

Double-Shot 3-D Displacement Field Measurement Using Hyperspectral Interferometry

by Tobias V. Reichold, Pablo D. Ruiz and Jonathan M. Huntley

Proceedings 2018, 2(8), 518; https://doi.org/10.3390/ICEM18-05406 - 28 Jun 2018

Cited by 1 | Viewed by 2134

A combination of a Michelson interferometer, a micro-optic element and a hyperspectral imager is used with broadband illumination to measure depth-resolved out-of-plane displacements without any scanning. Reference and deformed states of a transparent sample are recorded in single shots and used to evaluate [...] Read more.

A combination of a Michelson interferometer, a micro-optic element and a hyperspectral imager is used with broadband illumination to measure depth-resolved out-of-plane displacements without any scanning. Reference and deformed states of a transparent sample are recorded in single shots and used to evaluate the displacement field at different interfaces. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 417 KiB

Open AccessProceeding Paper

Efficient Use of the Output Information to Improve Modal Parameter Estimation

by Oscar Olarte, Mahmoud El-Kafafy and Patrick Guillaume

Proceedings 2018, 2(8), 519; https://doi.org/10.3390/ICEM18-05391 - 26 Jun 2018

Viewed by 1481

In modal identification, the value of the model parameters and the associated uncertainty depends on the quality of the measurements. The maximum likelihood estimator (

m l e

) is a consistent and efficient estimator. This means that the value of the parameters [...] Read more.

In modal identification, the value of the model parameters and the associated uncertainty depends on the quality of the measurements. The maximum likelihood estimator (

m l e

) is a consistent and efficient estimator. This means that the value of the parameters trends asymptotically close to the true value, while the variance of such parameters is the lowest possible with the associated data. The

m l e

implementation and application can be complex and generally need strong computational requirements. In applications where the number of inputs and outputs are elevated (as in modal analysis) is common to reduce the covariance matrix to a diagonal one where only the variances are considered. This implementation is still consistent but not efficient. However, it generates acceptable results. The current work shows that using efficiently the output information as complement to the input–output relations, it is possible to improve the model identification reaching similar levels than the

m l e

, while reducing the execution time and the computational load. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 598 KiB

Open AccessProceeding Paper

Design and Calibration of a 6-Component Balance on a Bicycle Steer

by Jordi D’hondt, Sien Dieltiens and Marc Juwet

Proceedings 2018, 2(8), 520; https://doi.org/10.3390/ICEM18-05414 - 29 Jun 2018

Cited by 1 | Viewed by 1875

The present article describes the methodology used to design and calibrate a 6-component balance. This balance is utilized in an instrumented bike measuring the forces applied on the handlebars. This instrumentation bike maps all riders induced loads. In the designing process, Finite Element [...] Read more.

The present article describes the methodology used to design and calibrate a 6-component balance. This balance is utilized in an instrumented bike measuring the forces applied on the handlebars. This instrumentation bike maps all riders induced loads. In the designing process, Finite Element Analysis was used. Calibrating the balance was done using the Least Square Regression Method which allows combining multiple loads during calibration and thus requires less samples. The balance operates with a maximum full scale error of 0.53%. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 480 KiB

Open AccessProceeding Paper

Application of Electronic Speckle Pattern Interferometry Method for Simultaneous Measurement of Young’s Modulus and the Poisson’s Ratio of Metals

by Alexandre Michtchenko

Proceedings 2018, 2(8), 521; https://doi.org/10.3390/ICEM18-05396 - 28 Jun 2018

Cited by 1 | Viewed by 1461

In this paper, mechanical experiments with a low-cost interferometry set-up are presented. The set-up is suitable for an undergraduate laboratory where optical equipment is absent. The arrangement consists of two planes of illumination, allowing the measurement of the two perpendicular in-plane displacement directions. [...] Read more.

In this paper, mechanical experiments with a low-cost interferometry set-up are presented. The set-up is suitable for an undergraduate laboratory where optical equipment is absent. The arrangement consists of two planes of illumination, allowing the measurement of the two perpendicular in-plane displacement directions. An axial load was applied to three different metals, and the longitudinal and transversal displacements were measured sequentially. A digital camera was used to acquire the images of the different states of the load of the illuminated area. A personal computer was used to perform the digital subtraction of the images to obtain the fringe correlations, which are needed to calculate the displacements. Finally, Young’s modulus and Poisson’s ratio of the metals were calculated using the displacement data. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2303 KiB

Open AccessProceeding Paper

Preliminary High-Temperature Tests of Textile Reinforced Concrete (TRC)

by Panagiotis Kapsalis, Tine Tysmans, Svetlana Verbruggen and Thanasis Triantafillou

Proceedings 2018, 2(8), 522; https://doi.org/10.3390/ICEM18-05416 - 29 Jun 2018

Cited by 3 | Viewed by 1832

Fire-testing of Textile Reinforced Concrete (TRC) is an interesting field in which quite limited research has been conducted so far. In this paper some preliminary tests are presented, where mortars used as binders are heated to 850 °C and their residual strength is [...] Read more.

Fire-testing of Textile Reinforced Concrete (TRC) is an interesting field in which quite limited research has been conducted so far. In this paper some preliminary tests are presented, where mortars used as binders are heated to 850 °C and their residual strength is tested, while the Ultrasonic Pulse Velocity (UPV) is also measured, before and after heating, and compared. Additionally, TRC specimens are subjected to flame exposure with a simple set-up and the residual strength is also tested by flexural tests. It is concluded that even with simple set-ups, interesting results can be obtained regarding the structural degradation of the material. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 513 KiB

Open AccessProceeding Paper

A Study on Designing Balloon Expandable Magnesium Alloy Stent for Optimization of Mechanical Characteristics

by Ichiro Shimizu, Akira Wada and Makoto Sasaki

Proceedings 2018, 2(8), 523; https://doi.org/10.3390/ICEM18-05398 - 28 Jun 2018

Cited by 2 | Viewed by 2296

Recently, the demand for a bio-absorbable coronary stent to promote recovery after an operation has increased. An option for such a stent is one made of a magnesium alloy, which has biodegradable properties. However, magnesium alloys have lower rigidity and lower ductility than [...] Read more.

Recently, the demand for a bio-absorbable coronary stent to promote recovery after an operation has increased. An option for such a stent is one made of a magnesium alloy, which has biodegradable properties. However, magnesium alloys have lower rigidity and lower ductility than other metals; as such, an appropriate stent structure is required to ensure radial rigidity. In this study, design parameters for an AZ31 magnesium alloy stent with sufficient radial rigidity were investigated. The necessary radial rigidity was determined by comparison tests against commercially available stents. The design parameters of the cell struts were selected and the optimum values to achieve high radial rigidity were investigated by means of elastic–plastic finite element analysis. Finally, a trial model stent based on the optimized design parameters was produced. It was confirmed that the model had sufficient radial rigidity, with no fracturing evident during crimping and expansion processes. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 644 KiB

Open AccessProceeding Paper

Investigation of the Interstitial Pore Pressure of Saturated Concrete under High Confinement

by Abdallah Accary, Laurent Daudeville and Yann Malecot

Proceedings 2018, 2(8), 524; https://doi.org/10.3390/ICEM18-05397 - 28 Jun 2018

Cited by 3 | Viewed by 1711

The objective of this study is to measure the interstitial pore pressure into saturated concrete under hundreds of megapascals of confinement. This study is carried out within a more general context aiming to understand the behavior of concrete structures under impact. It is [...] Read more.

The objective of this study is to measure the interstitial pore pressure into saturated concrete under hundreds of megapascals of confinement. This study is carried out within a more general context aiming to understand the behavior of concrete structures under impact. It is well known that the water saturation in massive concrete structures evolves from quasi-dry state at the surface to reach a quasi-saturated state at the core. Since the response of these structures under impact is highly linked to the state of saturation into the material, it is suspected that the pore pressure plays a major effect. This paper presents a new testing technique developed to measure the concrete pore pressure at high confining pressure. This latter is generated by means of a high capacity GIGA press. The new concept consists in implementing a pressure sensor into a water collecting cap. This cap is designed specially to collect water from concrete subjected to mechanical confinement pressure. Experimental results show that concrete pore pressure can reach values of the order of the confining pressure. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1037 KiB

Open AccessProceeding Paper

Damage Characterisation for Cement and Concrete Using Microwave Induced Damage

by Gareth R. Tear, Amitay H. Cohen, Danyal Magnus, David R. Sory and William G. Proud

Proceedings 2018, 2(8), 525; https://doi.org/10.3390/ICEM18-05418 - 30 Jun 2018

Cited by 1 | Viewed by 2692

Damage leading to failure in concrete and related materials is a complex behavior. Whilst many numerical approaches are available for simulating the degradation of material strength, it is difficult to discriminate between these models experimentally in the high strain rate ballistic impact regime. [...] Read more.

Damage leading to failure in concrete and related materials is a complex behavior. Whilst many numerical approaches are available for simulating the degradation of material strength, it is difficult to discriminate between these models experimentally in the high strain rate ballistic impact regime. An experimental method has been developed to determine when local material failure has occurred, and whether the failure can be classed as fracture or granular flow. This method is tested on Kolsky bar and ballistic impact experiments. Comparison with numerical simulations is presented. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1655 KiB

Open AccessProceeding Paper

Dynamic and Quasi-Static Testing and Modeling of Hot Stamped Tailor-Welded Axial Crush Rails

by Cale Peister, Cameron O’Keeffe, Jose Imbert, Clifford Butcher, Michael Worswick, Skye Malcolm, Jim Dykeman, Cyrus Yau, Ron Soldaat and Willie Bernert

Proceedings 2018, 2(8), 526; https://doi.org/10.3390/ICEM18-05401 - 26 Sep 2018

Cited by 3 | Viewed by 2168

In the current research, the use of tailor-welded blanks (TWBs) comprising Usibor^® 1500-AS laser welded to more ductile Ductibor^® 500-AS is considered. The TWBs were hot stamped to form top-hat cross-section channels with axially tailored properties. Axial crush rails were assembled [...] Read more.

In the current research, the use of tailor-welded blanks (TWBs) comprising Usibor^® 1500-AS laser welded to more ductile Ductibor^® 500-AS is considered. The TWBs were hot stamped to form top-hat cross-section channels with axially tailored properties. Axial crush rails were assembled by spot welding together two of these hot stamped channels along their flanges. The tailored rails were crush tested under dynamic (crash) and quasi-static conditions using an 855 kg crash sled facility at 10.6 m/s impact speed, and a 670 kN servo-hydraulic press at 0.5 mm/s, respectively. Non-tailored channels composed entirely of Ductibor^® 500-AS were also tested for base material characterization and as a comparison to the tailored conditions. Numerical models of the crash experiments were developed. The material models include measured fracture loci using the generalized incremental stress state dependent damage model (GISSMO), with rate sensitive constitutive behavior. Spot weld failure was also considered based on tests of spot welded coupons. The accuracy of the predicted force-displacement and energy absorption response, extent of parent metal cracking, and extent of weld failure are evaluated in comparison to the experiments. The difference in response between quasi-static and dynamic testing is also evaluated. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1369 KiB

Open AccessProceeding Paper

Digital Holographic Interferometry in the Long-Wave Infrared Range for Measuring Large Deformations of Space Components under Thermal-Vacuum Testing

by Jean-François Vandenrijt, Cédric Thizy, Fabian Languy and Marc Georges

Proceedings 2018, 2(8), 534; https://doi.org/10.3390/ICEM18-05430 - 9 Jul 2018

Cited by 1 | Viewed by 1609

Holographic interferometry at around 10 µm wavelengths has many advantages. It offers the possibility of large deformation measurement, while being much less sensitive to external perturbations. We present the state-of-the art of this technique applied to several industrial cases of the space industry. [...] Read more.

Holographic interferometry at around 10 µm wavelengths has many advantages. It offers the possibility of large deformation measurement, while being much less sensitive to external perturbations. We present the state-of-the art of this technique applied to several industrial cases of the space industry. In particular, we demonstrate that the technique is well adapted to measurement of full-field deformation maps of space structures undergoing large temperature variations typical to what they experience in space conditions. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 841 KiB

Open AccessProceeding Paper

Experimental Modal Analysis of Violins Made from Composites

by Tim Duerinck, Mathias Kersemans, Ewa Skrodzka, Marc Leman, Geerten Verberkmoes and Wim Van Paepegem

Proceedings 2018, 2(8), 535; https://doi.org/10.3390/ICEM18-05457 - 19 Jul 2018

Cited by 3 | Viewed by 1886

Six prototype violins made from composite materials are made and investigated using experimental modal analysis with the roving hammer method. The average FRF’s obtained show an influence of the materials on the vibrational response up to 2200 Hz. The A0 breathing mode and [...] Read more.

Six prototype violins made from composite materials are made and investigated using experimental modal analysis with the roving hammer method. The average FRF’s obtained show an influence of the materials on the vibrational response up to 2200 Hz. The A0 breathing mode and B1- mode are identified and are found to be significantly lower than in classical wooden violins. Additional measurements with a Laser Doppler Vibrometer and shaker found the same modes with a small difference in frequency (3–8 Hz). Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 1772 KiB

Open AccessProceeding Paper

Matching Spectroscopy with the Ultrasonic Polar Scan for Advanced NDT of Composites

by Erik Verboven, Mathias Kersemans, Arvid Martens, Jannes Daemen, Steven Delrue, Koen Van Den Abeele and Wim Van Paepegem

Proceedings 2018, 2(8), 536; https://doi.org/10.3390/ICEM18-05458 - 19 Jul 2018

Cited by 2 | Viewed by 1729

The Pulsed Ultrasonic Polar Scan (P-UPS) is a powerful technique for characterizing anisotropic materials like fiber reinforced plastics. A time-domain analysis of the ultrasonic signals yields amplitude and time-of-flight polar diagrams that provide a fingerprint of the local stiffness properties. Though, this simple [...] Read more.

The Pulsed Ultrasonic Polar Scan (P-UPS) is a powerful technique for characterizing anisotropic materials like fiber reinforced plastics. A time-domain analysis of the ultrasonic signals yields amplitude and time-of-flight polar diagrams that provide a fingerprint of the local stiffness properties. Though, this simple analysis ignores a lot of information contained in the ultrasonic signals. In this study, we propose to use the P-UPS technique in combination with the spectroscopic analysis of broadband pulses, to obtain plane wave transmission spectra for all in-plane polar angles. This allows us to combine on one hand the strengths of the P-UPS technique, that does not require a priori knowledge about the sample anisotropy, and on the other hand the frequency-domain analysis that utilizes information contained in the broadband pulses. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 2029 KiB

Open AccessProceeding Paper

The Use of 2D and 3D High-Speed Digital Image Correlation in Full Field Strain Measurements of Composite Materials Subjected to High Strain Rates

by Ahmed Elmahdy and Patricia Verleysen

Proceedings 2018, 2(8), 538; https://doi.org/10.3390/ICEM18-05439 - 9 Jul 2018

Cited by 3 | Viewed by 1989

The aim of this paper is to assess and compare the performance of both high speed 2D and 3D digital image correlation (DIC) configurations in the characterization of unidirectional carbon fiber reinforced epoxy composites in high strain rate tension in the transverse direction. [...] Read more.

The aim of this paper is to assess and compare the performance of both high speed 2D and 3D digital image correlation (DIC) configurations in the characterization of unidirectional carbon fiber reinforced epoxy composites in high strain rate tension in the transverse direction. The criteria for assessment were in terms of strain resolution and measuring the strain localization within the gauge section. Results showed the high-speed 3D DIC technique has lower strain resolution compared to the high-speed 2D DIC technique. In addition, the analysis of the full strain fields indicated that the 3D DIC technique could accurately locate and measure the concentrations of strains within the gauge section of the tested samples. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1051 KiB

Open AccessProceeding Paper

Investigation on Non-Linear Vibration Response of Cantilevered Thin Plates with Crack Using Electronic Speckle Pattern Interferometry

by Nan Tao, Yinhang Ma, Hanyang Jiang, Meiling Dai and Fujun Yang

Proceedings 2018, 2(8), 539; https://doi.org/10.3390/ICEM18-05456 - 19 Jul 2018

Cited by 2 | Viewed by 1617

The time-averaged electronic speckle pattern interferometry (ESPI) is employed to measure the frequencies and mode shapes of thin, cantilevered plates with root-slit. The first 12 order linear resonance frequency and mode shape of an intact cantilevered plate is determined by using FEM calculation. [...] Read more.

The time-averaged electronic speckle pattern interferometry (ESPI) is employed to measure the frequencies and mode shapes of thin, cantilevered plates with root-slit. The first 12 order linear resonance frequency and mode shape of an intact cantilevered plate is determined by using FEM calculation. The dynamic response of the intact specimen forced by a PZT actuator is measured and its super-harmonic resonance of forced response is investigated experimentally. The results show that the principal mode shape of super-harmonic vibration is similar to its natural modal. In contrast to linear forcing vibration, the threshold of force for super-harmonic resonance is much higher than that of the former. In addition, linear free response of four cantilevered root-slit plates with variation length of slit are analyzed by applying the FEM calculation, and their responses of forcing vibration were measured by using the ESPI method. The validity and accuracy of the numerical prediction are confirmed through experimental studies. The present work shows that the ESPI technique can provide whole-field and real-time measurement for vibration analysis and can also be employed for validation of the FEM calculation. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1382 KiB

Open AccessProceeding Paper

Blast Wave Assessment in a Compound Survival Container: Small-Scale Testing

by A. Caçoilo, R. Mourão, B. Belkassem, F. Teixeira-Dias, J. Vantomme and D. Lecompte

Proceedings 2018, 2(8), 540; https://doi.org/10.3390/ICEM18-05459 - 23 Jul 2018

Cited by 2 | Viewed by 1790

Propagation of shock waves in partially- or fully-confined environments is a complex phenomenon due to the possibility of multiple reflections, diffractions and superposition of waves. In a military context, the study of such phenomena is of extreme relevance to the evaluation of protection [...] Read more.

Propagation of shock waves in partially- or fully-confined environments is a complex phenomenon due to the possibility of multiple reflections, diffractions and superposition of waves. In a military context, the study of such phenomena is of extreme relevance to the evaluation of protection systems, such as survival containers, for personnel and equipment. True scale testing of such structures is costly and time consuming but small-scale models in combination with the Hopkinson-Cranz scaling laws are a viable alternative. This paper combines the use of a small-scale model of a compound survival container with finite element analysis (with LS-DYNA) to develop and validate a numerical model of the blast wave propagation. The first part of the study details the experimental set-up, consisting of a small-scale model of a survival container, which is loaded by the detonation of a scaled explosive charge. The pressure-time histories are recorded in several locations of the model. The second part of the study presents the numerical results and a comparison with the experimental data. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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6 pages, 925 KiB

Open AccessProceeding Paper

Load-Displacement Assessment of One-Way Reinforced Concrete (RC) Slabs Externally Strengthened Using CFRP Strips under Blast Loads

by R. Mourão, A. Maazoun, F. Teixeira-Dias, J. Vantomme and D. Lecompte

Proceedings 2018, 2(8), 541; https://doi.org/10.3390/ICEM18-05435 - 12 Jul 2018

Cited by 3 | Viewed by 1690

Dynamic behaviour of Reinforced Concrete (RC) structures can be assessed using a Single-Degree-of-Freedom (SDOF) approach. Such a method is highly dependent on the resistance curve of the structure which is generally represented by a bilinear elasto-perfectly-plastic approximation. This approximation might lead to erroneous [...] Read more.

Dynamic behaviour of Reinforced Concrete (RC) structures can be assessed using a Single-Degree-of-Freedom (SDOF) approach. Such a method is highly dependent on the resistance curve of the structure which is generally represented by a bilinear elasto-perfectly-plastic approximation. This approximation might lead to erroneous results when it refers to the use of externally bonded Fibre Reinforced composites for flexural capacity upgrade of Reinforced Concrete (RC), mainly when the concrete-to-FRP interface failure is to be included. One-way slabs are experimentally and numerically investigated in this study in a 3-point flexural configuration. Assessment on the load-displacement behaviour of a reference specimen and its retrofitted counterpart is performed. Special attention is given to the behaviour of the structure after the concrete-to-FRP failure. Comparison is made between experimental and numerical results and a good agreement is obtained. A complementary analytical study based on the SDOF method is conducted to understand the influence of several resistance curves on the overall displacement of the same structure when subjected to different pressure-impulse combinations. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 294 KiB

Open AccessProceeding Paper

Hypersonic Free Flight Investigation on Rudder Reflection of Aircraft

by Fei Xue, Yuchao Wang, Zenghui Jiang and Yinong Yang

Proceedings 2018, 2(8), 542; https://doi.org/10.3390/ICEM18-05434 - 12 Jul 2018

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In order to study the control effect of the rudder surface of the hypersonic vehicle and the coupling dynamic characteristics of the rudder surface deflection and the flight attitude, a technical platform for the deflection and motion coupling of the aircraft rudder surface [...] Read more.

In order to study the control effect of the rudder surface of the hypersonic vehicle and the coupling dynamic characteristics of the rudder surface deflection and the flight attitude, a technical platform for the deflection and motion coupling of the aircraft rudder surface was designed. The platform ejection mechanism can launch the model into the wind tunnel flow field according to the preset attitude, and model can free flight without support interference. The innovative design of the model internal rudder partial system can guarantee the model to deflect the rudder surface in the free flight process, simulate the real steering process of the aircraft. By changing spring with different springs, the speed of the rudder surface can be changed. The dual optical path and image acquisition technology can capture the motion picture before and after the deflection of the rudder surface from two angles. After the image is matched by model matching, the six degrees of freedom parameter of the model can be changed with the time curve before and after the deflection of the rudder surface, and the area of the six freedom degree curve of the different state model is compared. In other words, the specific influence of dynamic rudder rotation on the motion of the model is known. The wind tunnel test of the model in the hypersonic wind tunnel of the 500 mm is carried out using this platform. The test results are highly repeatable, and the test platform technology is mature and reliable. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 3029 KiB

Open AccessProceeding Paper

Design and Testing of Various Ceiling Elements Made of Carbon Reinforced Concrete

by Alexander Schumann, Sebastian May and Manfred Curbach

Proceedings 2018, 2(8), 543; https://doi.org/10.3390/ICEM18-05436 - 12 Jul 2018

Cited by 5 | Viewed by 1694

In this paper the design and recalculation of new type ceiling elements made of carbon reinforced concrete (CRC) is described. With the use of the high-potential composite material carbon reinforced concrete, structures can be, compared to conventional steel reinforced concrete (RC), designed and [...] Read more.

In this paper the design and recalculation of new type ceiling elements made of carbon reinforced concrete (CRC) is described. With the use of the high-potential composite material carbon reinforced concrete, structures can be, compared to conventional steel reinforced concrete (RC), designed and manufactured slimmer and lighter. Because of this and the increased sustainability of ceiling elements made of CRC a noteworthy amount of concrete can be saved. To show the potential of CRC elements, four different structures for various fields of application are shown. The first ceiling element, which will be introduced, fits perfectly for the use in multi-storey car parks because of the high resistance of the carbon fibers against corrosion. Another CRC structure in this paper was created in a research project as a demonstrator to show the potential of the newly developed concrete mixture for CRC. To prove the ability of this new developed concrete, large-scale CRC I-beams were produced in a precast concrete factory. The third ceiling element was designed and manufactured in form of a shell to combine the high strength composite material with an improved design for ceiling elements. The last introduced CRC element was developed as demonstrator in another research project and was designed in form of a ribbed slab. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 332 KiB

Open AccessProceeding Paper

Sensitivity Analysis of Fiber-Matrix Interface Parameters in an SMC Composite Damage Model

by Johannes Görthofer, Malte Schemmann, Thomas Seelig, Andrew Hrymak and Thomas Böhlke

Proceedings 2018, 2(8), 544; https://doi.org/10.3390/ICEM18-05438 - 12 Jul 2018

Cited by 2 | Viewed by 1979

This contribution shortly introduces the anisotropic, micromechanical damage model for sheet molding compound (SMC) composites presented in the authors’ previous publication [1]. As the considered material is a thermoset matrix reinforced with long (≈25 mm) glass fibers, the leading damage mechanisms are matrix [...] Read more.

This contribution shortly introduces the anisotropic, micromechanical damage model for sheet molding compound (SMC) composites presented in the authors’ previous publication [1]. As the considered material is a thermoset matrix reinforced with long (≈25 mm) glass fibers, the leading damage mechanisms are matrix micro-cracking and fiber-matrix interface debonding. Those mechanisms are modeled on the microscale and within a Mori-Tanaka homogenization framework. The model can account for arbitrary fiber orientation distributions. Matrix damage is considered as an isotropic stiffness degradation. Interface debonding is modeled via a Weibull interface strength distribution and the inhomogeneous stress distribution on the lateral fiber surface. Hereby, three independent parameters are introduced, that describe the interface strength and damage behavior, respectively. Due to the high non-linearity of the model, the influence of these parameters is not entirely clear. Therefore, the focus of this contribution lies on the variation and discussion of the above mentioned interface parameters. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 674 KiB

Open AccessProceeding Paper

Stress Attenuation and Energy Absorption of the Coral Sand with Different Particle Sizes under Impacts

by Xiao Yu, Li Chen, Qin Fang and Wuzheng Chen

Proceedings 2018, 2(8), 545; https://doi.org/10.3390/ICEM18-05440 - 12 Jul 2018

Cited by 2 | Viewed by 1598

The stress wave attenuation and energy absorption in the coral sand were respectively investigated. A series of experiments were carried out by using a new methodology with an improved split Hopkinson pressure bar (SHPB). Four types of coral sand, i.e., particle sizes of [...] Read more.

The stress wave attenuation and energy absorption in the coral sand were respectively investigated. A series of experiments were carried out by using a new methodology with an improved split Hopkinson pressure bar (SHPB). Four types of coral sand, i.e., particle sizes of 1.18–0.60 mm, 0.60–0.30 mm, 0.30–0.15 mm, and 0.15–0.075 mm, were carefully sieved and tested. Significant effects of coral sand on stress wave attenuation and energy absorption were observed. Correlation between stress wave attenuation and energy absorption of coral sand was validated. Conclusions on particle size effect of stress wave attenuation and energy absorption, which support each other, were drawn. There existed a common critical stress zone for coral sand with different particle sizes. When the stress below this zone, sand with small particle sizes attenuates stress wave better and absorb energy more; when the stress beyond this zone, sand with larger particle sizes behave better on stress wave attenuation and energy absorption. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 2811 KiB

Open AccessProceeding Paper

Detachment of Plasters in Masonry Buildings: Analysis by Acoustic Emission and Numerical Simulation

by Alessandro Grazzini, Giuseppe Lacidogna, Silvio Valente and Federico Accornero

Proceedings 2018, 2(8), 546; https://doi.org/10.3390/ICEM18-05431 - 9 Jul 2018

Viewed by 1367

An innovative laboratory procedure is described for testing the mechanical adhesion of new dehumidified mortars applied in the restoration works. A specific adherence test was carried out on composite specimens made by stone block and repair mortar. During the laboratory test the acoustic [...] Read more.

An innovative laboratory procedure is described for testing the mechanical adhesion of new dehumidified mortars applied in the restoration works. A specific adherence test was carried out on composite specimens made by stone block and repair mortar. During the laboratory test the acoustic emission (AE) technique was employed, in order to estimate the amount of energy released from fracture propagation in the adherence surface between mortar and stone. A numerical simulation follows the experimental data. The evolution of detachment process of mortar in a coupled stone brick–mortar system was analysed by AE signals, which can improve the numerical model and predict the failure mode in the adhesion surface of repair plaster. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 366 KiB

Open AccessProceeding Paper

Inversion for Damping Ratio of Flat Blade Based on BP Neural Network

by Xiamei Zhang and Shudan Xia

Proceedings 2018, 2(8), 547; https://doi.org/10.3390/ICEM18-05429 - 9 Jul 2018

Cited by 1 | Viewed by 1517

Aero engine is impacted by foreign objects frequently during daily usage, including runway gravel, birds, fuselage components and so on, so the fan and compressor may damage, resulting in serious air crash. Thus, simulating the impact of blades and establishing the numerical analysis [...] Read more.

Aero engine is impacted by foreign objects frequently during daily usage, including runway gravel, birds, fuselage components and so on, so the fan and compressor may damage, resulting in serious air crash. Thus, simulating the impact of blades and establishing the numerical analysis model of dynamic response demand immediate attention. In the analysis model, damping coefficient is one of the most important physical parameters of the blade structure and cannot be directly measured. Rayleigh damping is widely applied and can be converted to direct modal damping in ABAQUS. BP neural network is a multi-layer feedforward neural network using back propagation algorithm to adjust the network weights. It can be proved that there exists a three-layer BP network to realize the mapping of arbitrary continuous functions with arbitrary precision. In this study, a novel method for obtaining the damping ratio of the flat blade which applies BP neural network inversion is proposed. In order to demonstrate this method, a simplified experiment was conducted. Firstly, fix a section of aluminum plate and then conduct two set of drop tests on different positions with different impact velocities by a steel ball. At the same time, vibration response was recorded by displacement sensor. Secondly, establish a finite element model using ABAQUS to simulate the drop test. Adopt twenty groups of models with different damping ratio and then obtain their amplitudes and decay time, respectively. Thirdly, train a BP neural network using MATLAB program and then establish the mapping relationship between amplitude, decay time and damping ratio. Fourth, a set of experimental amplitude and decay time is substituted into the previously obtained BP neural network mapping model, and then the real damping ratio is obtained by inference. Finally, the real damping ratio is applied to the flat blade impact simulation of the other set of drop test for validation. The numerical results are consistent with the experimental data, which indicates that the damping ratio obtained by BP neural network inversion is reasonable and reliable. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 1226 KiB

Open AccessProceeding Paper

Transparent Object Shape Measurement Based on Deflectometry

by Zhichao Hao and Yuankun Liu

Proceedings 2018, 2(8), 548; https://doi.org/10.3390/ICEM18-05428 - 9 Jul 2018

Cited by 1 | Viewed by 1827

This paper proposes a method for obtaining surface normal orientation and 3-D shape of plano-convex lens using refraction stereo. We show that two viewpoints are sufficient to solve this problem under the condition that the refractive index of the object is known. What [...] Read more.

This paper proposes a method for obtaining surface normal orientation and 3-D shape of plano-convex lens using refraction stereo. We show that two viewpoints are sufficient to solve this problem under the condition that the refractive index of the object is known. What we need to know is that (1) an accurate function that maps each pixel to the refraction point caused by the refraction of the object. (2) light is refracted only once. In the simulation, the actual measurement process is simplified: light is refracted only once; and the accurate one-to-one correspondence between incident ray and refractive ray is realized by known object points. The deformed grating caused by refraction point is also constructed in the process of simulation. A plano-convex lens with a focal length of 242.8571 mm is used for stereo data acquisition, normal direction acquisition, and the judgment of normal direction consistency. Finally, restoring the three-dimensional information of the plano-convex lens by computer simulation. Simulation results suggest that our method is feasibility. In the actual experiment, considering the case of light is refracted more than once, combining the calibration data acquisition based on phase measurement, phase-shifting and temporal phase-unwrapping techniques to complete (1) calibrating the corresponding position relationship between the monitor and the camera (2) matching incident ray and refractive ray. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 1428 KiB

Open AccessProceeding Paper

Ultrasonic Measurement of Velocity Profile on Bubbly Flow Using a Single Resonant Frequency

by Wongsakorn Wongsaroj, Ari Hamdani, Natee Thong-un, Hideharu Takahashi and Hiroshige Kikura

Proceedings 2018, 2(8), 549; https://doi.org/10.3390/ICEM18-05445 - 16 Jul 2018

Cited by 6 | Viewed by 1983

The present paper describes a measurement technique for phase-separated velocity profile measurements in the two-phase bubbly flow. The Ultrasonic Velocity Profiler (UVP) method which is nonintrusive measurement, is applied to obtain an instantaneous velocity profile of liquid and bubble separately by using only [...] Read more.

The present paper describes a measurement technique for phase-separated velocity profile measurements in the two-phase bubbly flow. The Ultrasonic Velocity Profiler (UVP) method which is nonintrusive measurement, is applied to obtain an instantaneous velocity profile of liquid and bubble separately by using only one resonant frequency. To achieve this target, developed algorithm, which can decompose frequency component of the Doppler signal affected by liquid and bubble, is applied in the UVP system to obtain and separate instantaneous velocity profile of both phases. For confirming the applicability of modified measurement system, the developed UVP was used for the measurement of the velocity profile in bubbly flow on vertical pipe flow apparatus, the measurement accuracy was validated by UVP Original and Particle Image Velocimetry (PIV) method. Finally, the UVP was applied to experiment for observing velocity distribution of both phases in a bubble column. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 1286 KiB

Open AccessProceeding Paper

3D Shape Measurement Based on Digital Speckle Projection and Spatio-Temporal Correlation

by Qican Zhang, Renchao Xu, Yihang Liu and Zhenyi Chen

Proceedings 2018, 2(8), 552; https://doi.org/10.3390/ICEM18-05437 - 12 Jul 2018

Cited by 1 | Viewed by 1817

With the non-periodicity and discrete nature, and unnecessary of phase unwrapping process, digital speckle correlation method shows its significant advantages in three-dimensional (3D) shape measurement. Combining with the spatial correlation and temporal correlation method in the digital speckle correlation, a spatio-temporal digital speckle [...] Read more.

With the non-periodicity and discrete nature, and unnecessary of phase unwrapping process, digital speckle correlation method shows its significant advantages in three-dimensional (3D) shape measurement. Combining with the spatial correlation and temporal correlation method in the digital speckle correlation, a spatio-temporal digital speckle correlation was developed in this paper, which can improve the accuracy of 3D shape measurement and effectively reduce the number of the recorded speckle images for restoring the corresponding 3D shape at the same time. In the experiment, only 5 frames of the required speckle images was needed to reconstruct the 3D shape of a complex object with spatio-temporal digital speckle correlation method, and its accuracy was same as the result when 20 frames speckle images were used in temporal correlation method. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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8 pages, 725 KiB

Open AccessProceeding Paper

An Innovative Circular Ring Method for Measuring Young’s Modulus of Thin Flexible Multi-Layered Materials

by Atsumi Ohtsuki

Proceedings 2018, 2(8), 553; https://doi.org/10.3390/ICEM18-05441 - 12 Jul 2018

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An innovative mechanical testing method (Compressive Circular Ring Method) is provided for measuring Young’s modulus of each layer in a flexible multi-layered material. The method is based on a nonlinear large deformation theory. By just measuring the vertical displacement or the [...] Read more.

An innovative mechanical testing method (Compressive Circular Ring Method) is provided for measuring Young’s modulus of each layer in a flexible multi-layered material. The method is based on a nonlinear large deformation theory. By just measuring the vertical displacement or the horizontal displacement of the ring, Young’s modulus of each layer can be easily obtained for various thin multi-layered materials. Measurements were carried out on an electrodeposited twolayered wire. The results confirm that the new method is suitable for flexible multi-layered thin wires. In the meantime, the new method can be applied widely to measure Young’s modulus of thin layers formed by PVD, CVD, Coating, Paint, Cladding, Lamination, and others. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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10 pages, 3244 KiB

Open AccessProceeding Paper

Non-Destructive Testing of Composites by Ultrasound, Local Defect Resonance and Thermography

by Mathias Kersemans, Erik Verboven, Joost Segers, Saeid Hedayatrasa and Wim Van Paepegem

Proceedings 2018, 2(8), 554; https://doi.org/10.3390/ICEM18-05464 - 30 Jul 2018

Cited by 15 | Viewed by 4271

Different non-destructive testing techniques have been evaluated for detecting and assessing damage in carbon fiber reinforced plastics: (i) ultrasonic C-scan, (ii) local defect resonance of front/back surface and (iii) lock-in infrared thermography in reflection. Both artificial defects (flat bottom holes and inserts) and [...] Read more.

Different non-destructive testing techniques have been evaluated for detecting and assessing damage in carbon fiber reinforced plastics: (i) ultrasonic C-scan, (ii) local defect resonance of front/back surface and (iii) lock-in infrared thermography in reflection. Both artificial defects (flat bottom holes and inserts) and impact damage (barely visible impact damage) have been considered. The ultrasonic C-scans in reflection shows good performance in detecting the defects and in assessing actual defect parameters (e.g., size and depth), but it requires long scanning procedures and water coupling. The local defect resonance technique shows acceptable defect detectability, but has difficulty in extracting actual defect parameters without a priori knowledge. The thermographic inspection is by far the fastest technique, and shows good detectability of shallow defects (depth < 2 mm). Lateral sizing of shallow damage is also possible. The inspection of deeper defects (depth > 3–4 mm) in reflection is problematic and requires advanced post-processing approaches in order to improve the defect contrast to detectable limits. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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7 pages, 343 KiB

Open AccessProceeding Paper

Discrete Element Modelling of Compressive Strength Testing of No-Fines Concrete

by Zoltán Gyurkó and Rita Nemes

Proceedings 2018, 2(8), 555; https://doi.org/10.3390/ICEM18-05470 - 2 Aug 2018

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Discrete Element modelling of concrete requires the precise calibration of model parameters that is a long lasting and computationally expensive task in case of complex models. Present study introduces a method for estimating a model parameter (normal strength of parallel bonds) for concretes [...] Read more.

Discrete Element modelling of concrete requires the precise calibration of model parameters that is a long lasting and computationally expensive task in case of complex models. Present study introduces a method for estimating a model parameter (normal strength of parallel bonds) for concretes with different particle size distribution and aggregate type. The parameter estimation leads to an optimization problem based on physical measurement data. In the present paper, a model and its parameters are proposed to estimate normal strength of parallel bonds based on the density and compressive strength of concrete. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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5 pages, 308 KiB

Open AccessProceeding Paper

Phase-Shifting Shearing Interference Microscope with Savart Shear Prism and Rotatable Analyzer

by Shyh-Tsong Lin, Hưng-Xuân Trịnh, Zhe-Wei Chen and Yu-Hsin Lin

Proceedings 2018, 2(8), 556; https://doi.org/10.3390/ICEM18-05483 - 28 Aug 2018

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A phase-shifting shearing interference microscope (PSSIM) is introduced in this paper. It is constructed by placing a Savart shear prism between the objective and sample of a polarizing microscope with a rotatable analyzer as the phase-shifter, and it is capable of determining contour [...] Read more.

A phase-shifting shearing interference microscope (PSSIM) is introduced in this paper. It is constructed by placing a Savart shear prism between the objective and sample of a polarizing microscope with a rotatable analyzer as the phase-shifter, and it is capable of determining contour height variation and deformation strain using the principle of shearing interferometry. This paper not only interprets the measurement theory but also presents an experimental setup of the PSSIM. Moreover, this paper exhibits the results from the uses of the setup; the results demonstrate the validity and applicability of the PSSIM. Full article

(This article belongs to the Proceedings of The 18th International Conference on Experimental Mechanics)

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