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17 pages, 2985 KiB

Open AccessArticle

Buckling Analysis of Functionally Graded GPL-Reinforced Composite Plates Under Combined Thermal and Mechanical Loads

by Jin-Rae Cho

Materials 2025, 18(3), 567; https://doi.org/10.3390/ma18030567 - 26 Jan 2025

Viewed by 401

Abstract

The buckling-like mechanical behavior of functionally graded graphene platelet-reinforced composite (FG-GPLRC) structures is increasingly attracting research attention. However, buckling behavior has previously been studied separately as thermal buckling and mechanical buckling. In this context, this study investigates the buckling behavior of FG-GPLRC plates [...] Read more.

The buckling-like mechanical behavior of functionally graded graphene platelet-reinforced composite (FG-GPLRC) structures is increasingly attracting research attention. However, buckling behavior has previously been studied separately as thermal buckling and mechanical buckling. In this context, this study investigates the buckling behavior of FG-GPLRC plates under combined thermal and mechanical loads. The coupled buckling problem is formulated according to the minimum potential energy theorem using first-order shear deformation theory (FSDT). In addition, the problem is approximated by the 2-D natural element method (NEM), and the resulting coupled eigen matrix equations are derived to compute the critical buckling temperature rise (CBTR) and the mechanical buckling load. The developed numerical method can solve thermal, mechanical, and coupled thermo-mechanical buckling problems, and its reliability is examined through convergence and benchmark tests. Using the developed numerical method, the buckling behavior of FG-GPLRC plates under thermal and mechanical buckling loads is examined in depth with respect to the key parameters. In addition, a comparison with functionally graded CNT-reinforced composite (FG-CNTRC) plates is also presented. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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19 pages, 7232 KiB

Open AccessArticle

Finite Element Simulation of Acoustic Emissions from Different Failure Mechanisms in Composite Materials

by Manoj Rijal, David Amoateng-Mensah and Mannur J. Sundaresan

Materials 2024, 17(24), 6085; https://doi.org/10.3390/ma17246085 - 12 Dec 2024

Cited by 1 | Viewed by 832

Abstract

Damage in composite laminates evolves through complex interactions of different failure modes, influenced by load type, environment, and initial damage, such as from transverse impact. This paper investigates damage growth in cross-ply polymeric matrix laminates under tensile load, focusing on three primary failure [...] Read more.

Damage in composite laminates evolves through complex interactions of different failure modes, influenced by load type, environment, and initial damage, such as from transverse impact. This paper investigates damage growth in cross-ply polymeric matrix laminates under tensile load, focusing on three primary failure modes: transverse matrix cracks, delaminations, and fiber breaks in the primary loadbearing 0-degree laminae. Acoustic emission (AE) techniques can monitor and quantify damage in real time, provided the signals from these failure modes can be distinguished. However, directly observing crack growth and related AE signals is challenging, making numerical simulations a useful alternative. AE signals generated by the three failure modes were simulated using modified step impulses of appropriate durations based on incremental crack growth. Linear elastic finite element analysis (FEA) was applied to model the AE signal propagating as Lamb waves. Experimental attenuation data were used to modify the simulated AE waveforms by designing arbitrary magnitude response filters. The propagating waves can be detected as surface displacements or surface strains depending upon the type of sensor employed. This paper presents the signals corresponding to surface strains measured by surface-bonded piezoelectric sensors. Fiber break events showed higher-order Lamb wave modes with frequencies over 2 MHz, while matrix cracks primarily exhibited the fundamental S₀ and A₀ modes with frequencies ranging up to 650 kHz, with delaminations having a dominant A₀ mode and frequency content less than 250 kHz. The amplitude and frequency content of signals from these failure modes are seen to change significantly with source–sensor distance, hence requiring an array of dense sensors to acquire the signals effectively. Furthermore, the reasonable correlation between the simulated waveforms and experimental acoustic emission signals obtained during quasi-static tensile test highlights the effectiveness of FEA in accurately modeling these failure modes in composite materials. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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15 pages, 3374 KiB

Open AccessArticle

Reinforcing Bus Living Space with Recycled Carbon Fibers from Expired Prepreg in the Aircraft Industry

by Miguel Angel Martínez, Daniel Lavayen-Farfán, Juana Abenojar, María Jesús López-Boada and Daniel García-Pozuelo

Materials 2024, 17(23), 5958; https://doi.org/10.3390/ma17235958 - 5 Dec 2024

Viewed by 638

Abstract

Due to increasing mobility and energy conservation needs, improving bus and coach safety without adding weight is essential. Many crashes with fatal outcomes for vehicle occupants are associated with the rollover of the vehicle, revealing the structural weakness of the steel pillars between [...] Read more.

Due to increasing mobility and energy conservation needs, improving bus and coach safety without adding weight is essential. Many crashes with fatal outcomes for vehicle occupants are associated with the rollover of the vehicle, revealing the structural weakness of the steel pillars between windows, which must resist high levels of bending during rollovers. This study aims to reinforce these pillars with expired carbon fiber prepreg from the aircraft industry, improving safety and reducing environmental waste. To manufacture the pillars, shot-blasted hollow S275 steel tubes with a side length of 25 mm and a thickness of 1.5 mm were used. Bidirectional GG600T woven carbon fiber, CF, and aircraft-grade recycled carbon fiber-reinforced plastic, rCFRP, prepreg M21EV/IMA/3 were used as composite reinforcements. The first composite was made from a CF weave using the rigid epoxy resin Sicomin^® 8500/Sicomin^® SD8601. The rCFRP composite was frayed, and a new composite was made with the same rigid epoxy resin. Both composites were joined to the steel tube using a tough structural adhesive (SikaPower^® 1277). A third composite was obtained using the frayed rCFRP and the structural adhesive as a polymer matrix. All composites were treated with an APPT (atmospheric-pressure plasma torch) before being joined to the steel pillar with the structural adhesive. The comparison of the three reinforcements showed that the steel reinforced with the recycled prepreg composite manufactured with the rigid adhesive performed best, with a 50% increase in specific bending strength and only a 32% increase in weight. It also absorbed 71% more energy, which shows that this novel option for upcycling can noticeably increase the crashworthiness of structures. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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19 pages, 13917 KiB

Open AccessArticle

Investigation of Mechanical Properties and Color Changes of 3D-Printed Parts with Different Infill Ratios and Colors After Aging

by Oğuz Koçar, Nergizhan Anaç, Erhan Baysal, Furkan Parmaksız and İrfan Akgül

Materials 2024, 17(23), 5908; https://doi.org/10.3390/ma17235908 - 3 Dec 2024

Cited by 1 | Viewed by 928

Abstract

Since their inception, plastics have become indispensable materials. However, plastics used for extended periods in industrial applications are prone to aging, which negatively impacts their material behavior and performance. To ensure the long-term usability of these materials, they must be tested in real-time, [...] Read more.

Since their inception, plastics have become indispensable materials. However, plastics used for extended periods in industrial applications are prone to aging, which negatively impacts their material behavior and performance. To ensure the long-term usability of these materials, they must be tested in real-time, in-service environments to assess degradation. In practice, however, accelerated aging techniques are commonly employed to avoid time loss. Over time, various indicators of degradation in plastics emerge, such as changes in molecular weight, cracking, and mechanical properties like strain at break and impact strength. Among these, color deterioration or change is a critical factor that helps evaluate the service life of these materials. Considering the increasing use of plastics in 3D printing today, and the growing focus on strength over aesthetics in these applications, it is particularly useful to evaluate aging in plastics based on the relationship between color and strength. The wide application of 3D printing in various industries necessitates understanding material properties under aging conditions. This study examines the effects of aging on the mechanical behavior of polylactic acid (PLA) with three different colors (yellow, orange, and red) and three different infill ratios (20%, 60%, and 100%). The samples underwent an accelerated aging process of 432 h, which included 8 h of UV radiation, 15 min of water spraying, followed by 3 h and 45 min with the UV lamps turned off. Tensile tests, bending tests, hardness measurements, and color evaluations were conducted on the samples, linking the color changes after aging with the materials’ mechanical properties. The results show that after aging, yellow samples with a 100% infill ratio exhibited a 6.9% increase in tensile strength (44.50 MPa to 47.58 MPa). Orange samples with a 100% infill ratio were less affected by aging, while red samples experienced a decrease in tensile strength across all infill ratios. Regarding bending force, increases were observed in the orange, yellow, and red samples by 10.37%, 25.05%, and 8.87%, respectively. This study underscores the importance of color selection when designing 3D-printed materials for long-term applications. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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19 pages, 2022 KiB

Open AccessArticle

Environmental and Economic LCA Comparison of Flexural Strengthening Solutions for a Reinforced Concrete Beam

by Pedro Frazão Pedroso, João R. Correia, José D. Silvestre, João P. Firmo and Mário Garrido

Materials 2024, 17(23), 5879; https://doi.org/10.3390/ma17235879 - 30 Nov 2024

Viewed by 601

Abstract

The construction sector is one of the largest creators and distributors of wealth, contributing to economic growth worldwide. However, this economic growth comes together with very high environmental impacts. Thus, rehabilitation solutions that can adapt the current building stock to today’s structural requirements [...] Read more.

The construction sector is one of the largest creators and distributors of wealth, contributing to economic growth worldwide. However, this economic growth comes together with very high environmental impacts. Thus, rehabilitation solutions that can adapt the current building stock to today’s structural requirements are needed, increasing structural safety, while avoiding the production of demolition waste and the extraction of virgin raw materials, hence lowering the construction sector’s environmental impacts. Such rehabilitation solutions need to be environmentally and economically sound so that stakeholders can make informed decisions based on their needs and priorities. This paper presents a case study of an existing reinforced concrete beam, whose flexural resistance is increased using four alternative strengthening solutions: concrete jacketing, without and with increasing the cross-section size, and plate bonding, using either carbon fibre-reinforced polymer (CFRP) strips or steel plates. These solutions are studied via an environmental and economic cradle-to-gate life cycle assessment (LCA), resulting in a comprehensive comparison of their environmental and economic impacts, followed by a multicriteria and sensitivity analysis and eco-cost approach to determine the optimal solution. According to the criteria considered in the study, when environmental impacts are more valued, the concrete jacketing solution presents the best results and, when cost is dominant in the decision, the bonding of CFRP strips becomes the optimal solution. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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26 pages, 16612 KiB

Open AccessArticle

Dynamic Analysis and Vibration Control of Additively Manufactured Thin-Walled Polylactic Acid Polymer (PLAP) and PLAP Composite Beam Structures: Numerical Investigation and Experimental Validation

by Ali Raza, Magdalena Mieloszyk, Rūta Rimašauskienė and Vytautas Jūrėnas

Materials 2024, 17(22), 5478; https://doi.org/10.3390/ma17225478 - 9 Nov 2024

Viewed by 788

Abstract

This study primarily presents a numerical investigation of the dynamic behavior and vibration control in thin-walled, additively manufactured (AM) beam structures, validated through experimental results. Vibration control in thin-walled structures has gained significant attention recently because vibrations can severely affect structural integrity. Therefore, [...] Read more.

This study primarily presents a numerical investigation of the dynamic behavior and vibration control in thin-walled, additively manufactured (AM) beam structures, validated through experimental results. Vibration control in thin-walled structures has gained significant attention recently because vibrations can severely affect structural integrity. Therefore, it is necessary to minimize these vibrations or keep them within acceptable limits to ensure the structure’s integrity. In this study, the AM beam structures were made of polylactic acid polymer (PLAP), short carbon fiber reinforced in PLAP (SCFR|PLAP), and continuous carbon fiber reinforced in PLAP (CCFR|PLAP), with 0°|0° layer orientations. The finite element modeling (FEM) of the AM beam structures integrated with macro fiber composite (MFC) was carried out in Abaqus. The initial four modal frequencies of bending modes (BMs) and their respective modal shapes were acquired through numerical simulation. It is crucial to highlight the numerical findings that reveal discrepancies in the 1st modal frequencies of the beams, ranging up to 1.5% compared to their respective experimental values. For the 2nd, 3rd, and 4th modal frequencies, the discrepancies are within 10%. Subsequently, frequency response analysis (FRA) was carried out to observe the frequency-dependent vibration amplitude spectrum at the initial four BM frequencies. Despite discrepancy in the amplitude values between the numerical and experimental datasets, there was consistency in the overall amplitude behavior as frequency varied. THz spectroscopy was performed to identify voids or misalignment errors in the actual beam models. Finally, vibration amplitude control using MFC (M8507-P2) was examined in each kinematically excited numerical beam structure. After applying a counterforce with the MFC, the controlled vibration amplitudes for the PLAP, SCFR|PLAP, and CCFR|PLAP configurations were approximately ±19 µm, ±16 µm, and ±13 µm, respectively. The trend in the controlled amplitudes observed in the numerical findings was consistent with the experimental results. The numerical findings of the study reveal valuable insights for estimating trends related to vibration control in AM beam structures. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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17 pages, 11292 KiB

Open AccessArticle

Notch Effect in Acrylonitrile Styrene Acrylate (ASA) Single-Edge-Notch Bending Specimens Manufactured by Fused Filament Fabrication

by Sergio Cicero, Fabrizia Devito, Marcos Sánchez, Sergio Arrieta and Borja Arroyo

Materials 2024, 17(21), 5207; https://doi.org/10.3390/ma17215207 - 25 Oct 2024

Cited by 2 | Viewed by 891

Abstract

This paper analyses the notch effect in the fracture behaviour of acrylonitrile–styrene–acrylate (ASA) material manufactured by fused filament fabrication (FFF). The research is performed on 72 single-edge-notch bending (SENB) specimens containing U-notches with nominal notch radii varying from 0 mm (crack-like defects) up [...] Read more.

This paper analyses the notch effect in the fracture behaviour of acrylonitrile–styrene–acrylate (ASA) material manufactured by fused filament fabrication (FFF). The research is performed on 72 single-edge-notch bending (SENB) specimens containing U-notches with nominal notch radii varying from 0 mm (crack-like defects) up to 2.0 mm, and fabricated with three different raster orientations (0/90, 45/−45, 30/−60). Apparent fracture toughness values are obtained for the different conditions and the resulting notch effect is analysed through the Theory of Critical Distances. A fractographic analysis is also performed using Scanning Electron Microscopy (SEM) in order to justify the fracture (macroscopic) behaviour from the observed fracture micromechanisms. The notch effect observed in the three ASA raster orientations is very similar, and lower than that observed in other FFF polymeric alternatives (ABS, PLA). Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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13 pages, 6084 KiB

Open AccessArticle

Fractional Talbot Lithography for Predesigned Large-Area Liquid-Crystal Alignment

by Zhichao Ji, Zenghua Gan, Yu Wang, Zhijian Liu, Donghao Yang, Yujie Fan, Wenhua Li, Irena Drevensek-Olenik, Yigang Li and Xinzheng Zhang

Materials 2024, 17(19), 4810; https://doi.org/10.3390/ma17194810 - 30 Sep 2024

Viewed by 1082

Abstract

To address the increasing demands for cost-effective, large-area, and precisely patterned alignment of liquid crystals, a fractional Talbot lithography alignment technique was proposed. A light intensity distribution with a double spatial frequency of a photomask could be achieved based on the fractional Talbot [...] Read more.

To address the increasing demands for cost-effective, large-area, and precisely patterned alignment of liquid crystals, a fractional Talbot lithography alignment technique was proposed. A light intensity distribution with a double spatial frequency of a photomask could be achieved based on the fractional Talbot effect, which not only enhanced the resolution of lithography but also slashed system costs with remarkable efficiency. To verify the feasibility of the alignment method, we prepared a one-dimensional polymer grating as an alignment layer. A uniform alignment over a large area was achieved thanks to the perfect periodicity and groove depth of several hundred nanometers. The anchoring energy of the alignment layer was 1.82 × 10⁻⁴ J/m², measured using the twist balance method, which surpassed that of conventional rubbing alignment. Furthermore, to demonstrate its ability for non-uniform alignment, we prepared polymer concentric rings as an alignment layer, resulting in a liquid-crystal q-plate with q = 1 and

α_{0}

= π/2. This device, with a wide tuning range (phase retardation of ~6π @ 633 nm for 0 to 5 V), was used to generate special optical fields. The results demonstrate that this approach allows for the uniform large-area orientation of liquid-crystal molecules with superior anchoring energy and customizable patterned alignment, which has extensive application value in liquid-crystal displays, generating special optical fields and intricate liquid-crystal topological defects over a large area. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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22 pages, 10255 KiB

Open AccessArticle

Experimental and Numerical Insights into the Multi-Impact Response of Cork Agglomerates

by Guilherme J. Antunes e Sousa, Afonso J. C. Silva, Gabriel F. Serra, Fábio A. O. Fernandes, Susana P. Silva and Ricardo J. Alves de Sousa

Materials 2024, 17(19), 4772; https://doi.org/10.3390/ma17194772 - 28 Sep 2024

Viewed by 745

Abstract

Due to their extraordinary qualities, including fire resistance, excellent crashworthiness, low thermal conductivity, permeability, non-toxicity, and reduced density, cellular materials have found extensive use in various engineering applications. This study uses a finite element analysis (FEA) to model the dynamic compressive behaviour of [...] Read more.

Due to their extraordinary qualities, including fire resistance, excellent crashworthiness, low thermal conductivity, permeability, non-toxicity, and reduced density, cellular materials have found extensive use in various engineering applications. This study uses a finite element analysis (FEA) to model the dynamic compressive behaviour of agglomerated cork to ascertain how its material density and stress relaxation behaviour are related. Adding the Mullins effect into the constitutive modelling of impact tests, its rebound phase and subsequent second impact were further examined and simulated. Quasi-static and dynamic compression tests were used to evaluate the mechanical properties of three distinct agglomerated cork composite samples to feed the numerical model. According to the results, agglomerated cork has a significant capacity for elastic rebound, especially under dynamic strain rates, with minimal permanent deformation. For instance, the minimum value of its bounce-back energy is 11.8% of the initial kinetic energy, and its maximum permanent plastic deformation is less than 10%. The material’s model simulation adequately depicts the agglomerated cork’s response to initial and follow-up impacts by accurately reproducing the material’s dynamic compressive behaviour. In terms of innovation, this work stands out since it tackles the rebounding phenomena, which was not previously investigated in this group’s prior publication, either numerically or experimentally. Thus, this group has expanded the research on cork materials’ attributes. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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40 pages, 3816 KiB

Open AccessArticle

Multiscale Analysis of Sandwich Beams with Polyurethane Foam Core: A Comparative Study of Finite Element Methods and Radial Point Interpolation Method

by Jorge Belinha

Materials 2024, 17(18), 4466; https://doi.org/10.3390/ma17184466 - 11 Sep 2024

Viewed by 799

Abstract

This study presents a comprehensive multiscale analysis of sandwich beams with a polyurethane foam (PUF) core, delivering a numerical comparison between finite element methods (FEMs) and a meshless method: the radial point interpolation method (RPIM). This work aims to combine RPIM with homogenisation [...] Read more.

This study presents a comprehensive multiscale analysis of sandwich beams with a polyurethane foam (PUF) core, delivering a numerical comparison between finite element methods (FEMs) and a meshless method: the radial point interpolation method (RPIM). This work aims to combine RPIM with homogenisation techniques for multiscale analysis, being divided in two phases. In the first phase, bulk PUF material was modified by incorporating circular holes to create PUFs with varying volume fractions. Then, using a homogenisation technique coupled with FEM and four versions of RPIM, the homogenised mechanical properties of distinct PUF with different volume fractions were determined. It was observed that RPIM formulations, with higher-order integration schemes, are capable of approximating the solution and field smoothness of high-order FEM formulations. However, seeking a comparable field smoothness represents prohibitive computational costs for RPIM formulations. In a second phase, the obtained homogenised mechanical properties were applied to large-scale sandwich beam problems with homogeneous and approximately functionally graded cores, showing RPIM’s capability to closely approximate FEM results. The analysis of stress distributions along the thickness of the beam highlighted RPIM’s tendency to yield lower stress values near domain edges, albeit with convergence towards agreement among different formulations. It was found that RPIM formulations with lower nodal connectivity are very efficient, balancing computational cost and accuracy. Overall, this study shows RPIM’s viability as an alternative to FEM for addressing practical elasticity applications. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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22 pages, 11550 KiB

Open AccessArticle

Effects of Rubber Core on the Mechanical Behaviour of the Carbon–Aramid Composite Materials Subjected to Low-Velocity Impact Loading Considering Water Absorption

by Stefania Ursache, Camelia Cerbu, Anton Hadăr and Horia Alexandru Petrescu

Materials 2024, 17(16), 4055; https://doi.org/10.3390/ma17164055 - 15 Aug 2024

Viewed by 1065

Abstract

The large-scale use of composite materials reinforced with carbon–aramid hybrid fabric in various outdoor applications, which ensures increased mechanical resistance including in impact loadings, led to the need to investigate the effects of aggressive environmental factors (moisture absorption, temperature, thermal cycles, ultra-violet rays) [...] Read more.

The large-scale use of composite materials reinforced with carbon–aramid hybrid fabric in various outdoor applications, which ensures increased mechanical resistance including in impact loadings, led to the need to investigate the effects of aggressive environmental factors (moisture absorption, temperature, thermal cycles, ultra-violet rays) on the variation of their mechanical properties. Since the literature is still lacking in research on this topic, this article aims to compare the low-velocity impact behaviour of two carbon–aramid hybrid composite materials (with and without rubber core) and to investigate the effects of water absorption on impact properties. The main objectives of this research were as follows: (i) the investigation of the mechanical behavior in tests for two impact energies of 25 J and 50 J; (ii) comparison of the results obtained in terms of the force, displacement, velocity, and energy related to the time; (iii) analysis of the water absorption data; (iii) low-velocity impact testing of wet specimens after saturation; (iv) comparison between the impact behaviour of the wet specimens with that of the dried ones. One of the main findings was that for the wet specimens without rubber core, absorbed impact energy was 16% less than the one recorded for dried specimens at an impact energy of 50 J. The failure modes of the dried specimens without rubber core are breakage for both carbon and aramid fibres, matrix cracks, and delamination at matrix–fibre interfaces. The degradation for the wet specimens with rubber core is much more pronounced because the decrease in the absorbed impact energy was 53.26% after 10,513 h of immersion in water and all the layers were broken. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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19 pages, 8083 KiB

Open AccessArticle

Magnetodielectric and Rheological Effects in Magnetorheological Suspensions Based on Lard, Gelatin and Carbonyl Iron Microparticles

by Octavian Madalin Bunoiu, Ioan Bica, Eugen Mircea Anitas and Larisa Marina Elisabeth Chirigiu

Materials 2024, 17(16), 3941; https://doi.org/10.3390/ma17163941 - 8 Aug 2024

Viewed by 1215

Abstract

This study aims to develop low-cost, eco-friendly, and circular economy-compliant composite materials by creating three types of magnetorheological suspensions (MRSs) utilizing lard, carbonyl iron (CI) microparticles, and varying quantities of gelatin particles (GP). These MRSs serve as dielectric materials in cylindrical cells used [...] Read more.

This study aims to develop low-cost, eco-friendly, and circular economy-compliant composite materials by creating three types of magnetorheological suspensions (MRSs) utilizing lard, carbonyl iron (CI) microparticles, and varying quantities of gelatin particles (GP). These MRSs serve as dielectric materials in cylindrical cells used to fabricate electric capacitors. The equivalent electrical capacitance (C) of these capacitors is measured under different magnetic flux densities (

B \leq 160

mT) superimposed on a medium-frequency electric field (f = 1 kHz) over a period of 120 s. The results indicate that at high values of B, increasing the GP content to 20 vol.% decreases the capacitance C up to about one order of magnitude compared to MRS without GP. From the measured data, the average values of capacitance

C_{m}

are derived, enabling the calculation of relative dielectric permittivities (

ϵ_{r}^{'}

) and the dynamic viscosities (

η

) of the MRSs. It is demonstrated that

ϵ_{r}^{'}

and

η

can be adjusted by modifying the MRS composition and fine-tuned through the magnetic flux density B. A theoretical model based on the theory of dipolar approximations is used to show that

ϵ_{r}^{'}

,

η

, and the magnetodielectric effect can be coarsely adjusted through the composition of MRSs and finely adjusted through the values B of the magnetic flux density. The ability to fine-tune these properties highlights the versatility of these materials, making them suitable for applications in various industries, including electronics, automotive, and aerospace. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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26 pages, 9203 KiB

Open AccessArticle

Synthesis and Characterisation of Nanocrystalline Co_xFe_1−xGDC Powders as a Functional Anode Material for the Solid Oxide Fuel Cell

by Laura Quinlan, Talia Brooks, Nasrin Ghaemi, Harvey Arellano-Garcia, Maryam Irandoost, Fariborz Sharifianjazi and Bahman Amini Horri

Materials 2024, 17(15), 3864; https://doi.org/10.3390/ma17153864 - 4 Aug 2024

Viewed by 1563

Abstract

The necessity for high operational temperatures presents a considerable obstacle to the commercial viability of solid oxide fuel cells (SOFCs). The introduction of active co-dopant ions to polycrystalline solid structures can directly impact the physiochemical and electrical properties of the resulting composites including [...] Read more.

The necessity for high operational temperatures presents a considerable obstacle to the commercial viability of solid oxide fuel cells (SOFCs). The introduction of active co-dopant ions to polycrystalline solid structures can directly impact the physiochemical and electrical properties of the resulting composites including crystallite size, lattice parameters, ionic and electronic conductivity, sinterability, and mechanical strength. This study proposes cobalt–iron-substituted gadolinium-doped ceria (Co_xFe_1-xGDC) as an innovative, nickel-free anode composite for developing ceramic fuel cells. A new co-precipitation technique using ammonium tartrate as the precipitant in a multi-cationic solution with Co²⁺, Gd³⁺, Fe³⁺, and Ce³⁺ ions was utilized. The physicochemical and morphological characteristics of the synthesized samples were systematically analysed using a comprehensive set of techniques, including DSC/TGA for a thermal analysis, XRD for a crystallographic analysis, SEM/EDX for a morphological and elemental analysis, FT-IR for a chemical bonding analysis, and Raman spectroscopy for a vibrational analysis. The morphological analysis, SEM, showed the formation of nanoparticles (≤15 nm), which corresponded well with the crystal size determined by the XRD analysis, which was within the range of ≤10 nm. The fabrication of single SOFC bilayers occurred within an electrolyte-supported structure, with the use of the GDC as the electrolyte layer and the CoO–Fe₂O₃/GDC composite as the anode. SEM imaging and the EIS analysis were utilized to examine the fabricated symmetrical cells. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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13 pages, 2340 KiB

Open AccessArticle

A Perovskite Material Screening and Performance Study Based on Asymmetric Convolutional Blocks

by Shumin Ji, Yujie Zhang, Yanyan Huang, Zhongwei Yu, Yong Zhou and Xiaogang Lin

Materials 2024, 17(15), 3741; https://doi.org/10.3390/ma17153741 - 28 Jul 2024

Viewed by 1225

Abstract

This study introduces an innovative method for identifying high-efficiency perovskite materials using an asymmetric convolution block (ACB). Our approach involves preprocessing extensive data on perovskite oxide materials and developing a precise predictive model. This system is designed to accurately predict key properties such [...] Read more.

This study introduces an innovative method for identifying high-efficiency perovskite materials using an asymmetric convolution block (ACB). Our approach involves preprocessing extensive data on perovskite oxide materials and developing a precise predictive model. This system is designed to accurately predict key properties such as band gap and stability, thereby eliminating the reliance on traditional feature importance filtering. It exhibited outstanding performance, achieving an accuracy of 96.8% and a recall of 0.998 in classification tasks, and a coefficient of determination (R²) value of 0.993 with a mean squared error (MSE) of 0.004 in regression tasks. Notably, DyCoO₃ and YVO₃ were identified as promising candidates for photovoltaic applications due to their optimal band gaps. This efficient and precise method significantly advances the development of advanced materials for solar cells, providing a robust framework for rapid material screening. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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Review

Jump to: Research

22 pages, 2333 KiB

Open AccessReview

Recent Advancements in Fabrication of Metal Matrix Composites: A Systematic Review

by Pallab Sarmah and Kapil Gupta

Materials 2024, 17(18), 4635; https://doi.org/10.3390/ma17184635 - 21 Sep 2024

Cited by 5 | Viewed by 2142

Abstract

Metal matrix composites (MMCs) are essential materials in various industries due to superior properties, such as high strength-to-weight ratios, better corrosion resistance, improved wear resistance and adaptability, developed by continuous improvements in their fabrication methods. This helps to meet the growing demand for [...] Read more.

Metal matrix composites (MMCs) are essential materials in various industries due to superior properties, such as high strength-to-weight ratios, better corrosion resistance, improved wear resistance and adaptability, developed by continuous improvements in their fabrication methods. This helps to meet the growing demand for high-performance and sustainable products. The industries that stand to gain the most are automotive and aerospace, where MMCs are used for car parts, airplane frames, and jet engines that need to be strong and lightweight. Furthermore, MMCs are being extensively used in the biomedical industry for implants and medical equipment because of their suitable mechanical integrity and corrosion resistance. Applications in heavy construction, defense, and even space exploration are noteworthy. The advancements in fabrication of MMCs have revolutionized the composite industry with their improved mechanical, tribological, and metallurgical properties. This review article offers an introduction and thorough examination of the most recent advancements (mostly within the last five years) in fabrication methods of MMCs. The novelty and modernization in the traditional processes and advanced processes are covered, along with discussing the process parameters’ effects on the microstructure and properties of the composites. The review focuses on features and prospective applications of MMCs that have been greatly improved and extended due to such advancements. The most recent methods for developing MMCs, including friction stir processing (FSP), ultrasonic-assisted stir casting, and additive manufacturing, are discussed. Artificial intelligence and machine learning interventions for composite manufacturing are also included in this review. This article aims to assist researchers and scholars and encourage them to conduct future research and pursue innovations to establish the field further. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition)

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