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4 pages, 174 KiB

Open AccessEditorial

Special Issue: “Feature Papers in Materials Simulation and Design”

by Michele Bacciocchi and Abbas S. Milani

Materials 2023, 16(5), 1900; https://doi.org/10.3390/ma16051900 - 24 Feb 2023

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Abstract

The title of the current Special Issue, “Feature Papers in Materials Simulation and Design”, has identified the aims of this collection since its opening: the gathering of research works and comprehensive review papers that advance the understanding and prediction of material behavior at [...] Read more.

The title of the current Special Issue, “Feature Papers in Materials Simulation and Design”, has identified the aims of this collection since its opening: the gathering of research works and comprehensive review papers that advance the understanding and prediction of material behavior at different scales, from atomistic to macroscopic, through innovative modeling and simulation [...] Full article

(This article belongs to the Special Issue Feature Papers in Materials Simulation and Design)

Research

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33 pages, 12603 KiB

Open AccessEditor’s ChoiceArticle

Application of the ps−Version of the Finite Element Method to the Analysis of Laminated Shells

by Cheng Angelo Yan and Riccardo Vescovini

Materials 2023, 16(4), 1395; https://doi.org/10.3390/ma16041395 - 7 Feb 2023

Cited by 2 | Viewed by 1801

Abstract

The development of accurate and efficient numerical methods is of crucial importance for the analysis and design of composite structures. This is even more true in the presence of variable stiffness (VS) configurations, where intricate load paths can be responsible for complex and [...] Read more.

The development of accurate and efficient numerical methods is of crucial importance for the analysis and design of composite structures. This is even more true in the presence of variable stiffness (VS) configurations, where intricate load paths can be responsible for complex and localized stress profiles. In this work, we present the

p s -

version of the finite elements method (

p s -

FEM), a novel FE approach which can perform global/local analysis through different refinement strategies efficiently and easily. Within this framework, the global behavior is captured through a

p -

refinement by increasing the polynomial order of the elements. For the local one, a mesh−superposition technique, called

s -

refinement, is used to improve locally the solution by defining a local/fine mesh overlaid to the global/coarse one. The combination of

p -

and

s -

refinements enables us to achieve excellent accuracy−to−cost ratios. This paper aims to present the numerical formulation and the implementation aspects of this novel approach to VS composite shell analysis. Numerical tests are reported to illustrate the potential of the method. The results provide a clear insight of its potential to guarantee fast convergence and easy mesh refinement where needed. Full article

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12 pages, 3298 KiB

Open AccessArticle

Viscoelasticity in Large Deformation Analysis of Hyperelastic Structures

by Shahriar Dastjerdi, Bekir Akgöz and Ömer Civalek

Materials 2022, 15(23), 8425; https://doi.org/10.3390/ma15238425 - 26 Nov 2022

Cited by 3 | Viewed by 1759

Abstract

In this paper, an annular/circular plate made of hyperelastic material and considering the viscoelastic property was investigated based on a novel nonlinear elasticity theory. A new approach for hyperelastic materials in conjunction with the Kelvin–Voigt scheme is employed to obtain the structure’s large [...] Read more.

In this paper, an annular/circular plate made of hyperelastic material and considering the viscoelastic property was investigated based on a novel nonlinear elasticity theory. A new approach for hyperelastic materials in conjunction with the Kelvin–Voigt scheme is employed to obtain the structure’s large deformation under uniform transverse loading. The constitutive equations were extracted using the energy method. The derived partial differential time-dependent equations have been solved via the semi-analytical polynomial method (SAPM). The obtained results have been validated by ABAQUS software and the available paper. In consequence, a good agreement between the results was observed. Finally, several affecting parameters on the analysis have been attended to and studied, such as the nonlinear elasticity analysis, the boundary conditions, loading, and the material’s viscosity. It can be possible to obtain the needed time for achieving the final deformation of the structure based on the applied analysis in this research. Full article

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19 pages, 4172 KiB

Open AccessArticle

An Experimental and Numerical Study of the Influence of Temperature on Mode II Fracture of a T800/Epoxy Unidirectional Laminate

by Yu Gong, Linfei Jiang, Linkang Li and Jian Zhao

Materials 2022, 15(22), 8108; https://doi.org/10.3390/ma15228108 - 16 Nov 2022

Cited by 11 | Viewed by 1780

Abstract

Studies on mode II fracture have promoted the establishment of the delamination theory for unidirectional composite laminates at room temperature. However, under thermal conditions, the fracture behavior of composite laminates will exhibit certain differences. The delamination theory should be extended to consider the [...] Read more.

Studies on mode II fracture have promoted the establishment of the delamination theory for unidirectional composite laminates at room temperature. However, under thermal conditions, the fracture behavior of composite laminates will exhibit certain differences. The delamination theory should be extended to consider the temperature effect. To achieve this goal, in this study, the mode II static delamination growth behavior of an aerospace-grade T800/epoxy composite is investigated at 23 °C, 80 °C and 130 °C. The mode II fracture resistance curve (R-curve) is experimentally determined. A fractographic study on the fracture surface is performed using a scanning electron microscope (SEM), in order to reveal the failure mechanism. In addition, a numerical framework based on the cohesive zone model with a bilinear constitutive law is established for simulating the mode II delamination growth behavior at the thermal condition. The effects of the interfacial parameters on the simulations are investigated and a suitable value set for the interfacial parameters is determined. Good agreements between the experimental and numerical load–displacement responses illustrate the applicability of the numerical model. The research results provide helpful guidance for the design of composite laminates and an effective numerical method for the simulation of mode II delamination growth behavior. Full article

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12 pages, 4321 KiB

Open AccessArticle

The Effect of Different Morphologies of WO₃/GO Nanocomposite on Photocatalytic Performance

by Banu Esencan Türkaslan, Aziz Kerim Çelik, Ayça Dalbeyler and Nicholas Fantuzzi

Materials 2022, 15(22), 8019; https://doi.org/10.3390/ma15228019 - 14 Nov 2022

Cited by 9 | Viewed by 1777

Abstract

Tungsten trioxide/graphene oxide (WO₃/GO) nanocomposites have been successfully synthesized using in situ and ex situ chemical approaches. Graphite and tungsten carbide (WC) were employed to perform in situ synthesis, and WO₃ and GO were employed to perform the ex situ [...] Read more.

Tungsten trioxide/graphene oxide (WO₃/GO) nanocomposites have been successfully synthesized using in situ and ex situ chemical approaches. Graphite and tungsten carbide (WC) were employed to perform in situ synthesis, and WO₃ and GO were employed to perform the ex situ synthesis of WO₃/GO nanocomposites. GO, which was required for ex situ synthesis, is synthesized via the modified and improved Hummers method. XRD, SEM/EDS, and FTIR are used for the characterization of the nanocomposite. From the XRD of the WO₃/GO nanocomposites, it was observed that WO₃ distributed uniformly on graphene oxide sheets or was incorporated between the sheets. The photocatalytic activities of WO₃/GO nanocomposites were evaluated by methylene blue (MB) adsorption and visible light photocatalytic degradation activities by UV-vis spectroscopy. The results showed that the efficiency of the photocatalytic activity of the nanocomposite depends on different synthesis methods and the morphology resulting from the changed method. WO₃/GO nanocomposites synthesized by both methods exhibited much higher photocatalytic efficiencies than pure WO₃, and the best degradation efficiencies for MB was 96.30% for the WO₃/GO in situ synthesis nanocomposite. Full article

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12 pages, 2136 KiB

Open AccessArticle

Bimetallic Thin-Walled Box Beam Thermal Buckling Response

by Sandra Kvaternik Simonetti, Goran Turkalj, Damjan Banić and Domagoj Lanc

Materials 2022, 15(21), 7537; https://doi.org/10.3390/ma15217537 - 27 Oct 2022

Cited by 1 | Viewed by 1333

Abstract

A beam model for thermal buckling analysis of a bimetallic box beam is presented. The Euler–Bernoulli–Vlasov beam theory is employed considering large rotations but small strains. The nonlinear stability analysis is performed using an updated Lagrangian formulation. In order to account for the [...] Read more.

A beam model for thermal buckling analysis of a bimetallic box beam is presented. The Euler–Bernoulli–Vlasov beam theory is employed considering large rotations but small strains. The nonlinear stability analysis is performed using an updated Lagrangian formulation. In order to account for the thermal effects of temperature-dependent (TD) and temperature-independent (TID) materials, a uniform temperature rise through beam wall thickness is considered. The numerical results for thin-walled box beams are presented to investigate the effects of different boundary conditions, beam lengths and material thickness ratios on the critical buckling temperature and post-buckling responses. The effectiveness and accuracy of the proposed model are verified by means of comparison with a shell model. It is revealed that all of the abovementioned effects are invaluable for buckling analysis of thin-walled beams under thermal load. Moreover, it is shown that the TD solutions give lower values than the TID one, emphasizing the importance of TD materials in beams. Full article

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25 pages, 10881 KiB

Open AccessArticle

Nonlocal Free Vibration of Embedded Short-Fiber-Reinforced Nano-/Micro-Rods with Deformable Boundary Conditions

by Ömer Civalek, Büşra Uzun and Mustafa Özgür Yaylı

Materials 2022, 15(19), 6803; https://doi.org/10.3390/ma15196803 - 30 Sep 2022

Cited by 7 | Viewed by 1805

Abstract

An efficient eigenvalue algorithm is developed for the axial vibration analysis of embedded short-fiber-reinforced micro-/nano-composite rods under arbitrary boundary conditions. In the formulation, nonlocal elasticity theory is used to capture the size effect, and the deformable boundary conditions at the ends are simulated [...] Read more.

An efficient eigenvalue algorithm is developed for the axial vibration analysis of embedded short-fiber-reinforced micro-/nano-composite rods under arbitrary boundary conditions. In the formulation, nonlocal elasticity theory is used to capture the size effect, and the deformable boundary conditions at the ends are simulated using two elastic springs in the axial direction. In addition, to determine the reinforcing effect of restrained nano-/micro-rods, a new system of linear equations with the concept of the infinite power series is presented. After performing the mathematical processes known as Fourier sine series, Stokes’ transformation and successive integration, we finally obtain a coefficient matrix in terms of infinite series for various rigid or deformable boundary conditions. Some accurate eigenvalue solutions of the free axial vibration frequencies of the short-fiber-reinforced micro-/nano-composite rods with and without being restrained by the means of elastic springs are given to show the performance of the present method. The presence of the elastic spring boundary conditions changes the axial vibration frequencies and corresponding mode shapes. Full article

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21 pages, 7238 KiB

Open AccessArticle

On the Numerical Modeling of Flax/PLA Bumper Beams

by Liu Jiao-Wang, José A. Loya and Carlos Santiuste

Materials 2022, 15(16), 5480; https://doi.org/10.3390/ma15165480 - 9 Aug 2022

Cited by 6 | Viewed by 1806

Abstract

Significant progress has been made in green composites developing fully biodegradable composites made of microbially degradable polymers reinforced with natural fibers. However, an improvement in the development of numerical models to predict the damage of green composites is necessary to extend their use [...] Read more.

Significant progress has been made in green composites developing fully biodegradable composites made of microbially degradable polymers reinforced with natural fibers. However, an improvement in the development of numerical models to predict the damage of green composites is necessary to extend their use in industrial applications of structural responsibility. This paper is focused on developing a numerical model that can predict the failure modes of four types of bumper beams made of flax/PLA green composites with different cross sections. The predictions regarding energy absorption, contact force history, and extension of delamination were compared with experimental results to validate the FEM model, and both results revealed a good agreement. Finally, the FEM model was used to analyze the failure modes of the bumper beams as a function of the impact energy and cross-section roundness. The impact energy threshold defined as the maximum absorbed-energy capability of the beam match with the impact energy that produces delaminations extended through all the cross sections. Experimental and numerical results revealed that the threshold energy, where the maximum energy-absorption capability is reached, for Type A is over 60 J; for Type B and C is around 60 J; and for Type D is at 50 J. Since delamination is concentrated at the cross-section corners, the threshold energy decreases with the cross-section roundness because the higher the roundness ratio, the wider the delamination extension. Full article

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20 pages, 7285 KiB

Open AccessArticle

Can a Black-Box AI Replace Costly DMA Testing?—A Case Study on Prediction and Optimization of Dynamic Mechanical Properties of 3D Printed Acrylonitrile Butadiene Styrene

by Ronak Vahed, Hamid R. Zareie Rajani and Abbas S. Milani

Materials 2022, 15(8), 2855; https://doi.org/10.3390/ma15082855 - 13 Apr 2022

Cited by 11 | Viewed by 1911

Abstract

The complex and non-linear nature of material properties evolution during 3D printing continues to make experimental optimization of Fused Deposition Modeling (FDM) costly, thus entailing the development of mathematical predictive models. This paper proposes a two-stage methodology based on coupling limited data experiments [...] Read more.

The complex and non-linear nature of material properties evolution during 3D printing continues to make experimental optimization of Fused Deposition Modeling (FDM) costly, thus entailing the development of mathematical predictive models. This paper proposes a two-stage methodology based on coupling limited data experiments with black-box AI modeling and then performing heuristic optimization, to enhance the viscoelastic properties of FDM processed acrylonitrile butadiene styrene (ABS). The effect of selected process parameters (including nozzle temperature, layer height, raster orientation and deposition speed) as well as their combinative effects are also studied. Specifically, in the first step, a Taguchi orthogonal array was employed to design the Dynamic Mechanical Analysis (DMA) experiments with a minimal number of runs, while considering different working conditions (temperatures) of the final prints. The significance of process parameters was measured using Lenth’s statistical method. Combinative effects of FDM parameters were noted to be highly nonlinear and complex. Next, artificial neural networks were trained to predict both the storage and loss moduli of the 3D printed samples, and consequently, the process parameters were optimized via Particle Swarm Optimization (PSO). The optimized process of the prints showed overall a closer behavior to that of the parent (unprocessed) ABS, when compared to the unoptimized set-up. Full article

(This article belongs to the Special Issue Feature Papers in Materials Simulation and Design)

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29 pages, 9696 KiB

Open AccessEditor’s ChoiceArticle

The Use of a High-Pressure Water-Ice Jet for Removing Worn Paint Coating in Renovation Process

by Grzegorz Chomka, Jarosław Chodór, Leon Kukiełka and Maciej Kasperowicz

Materials 2022, 15(3), 1168; https://doi.org/10.3390/ma15031168 - 3 Feb 2022

Cited by 3 | Viewed by 2362

Abstract

The paper presents the results of investigations into the possibility of using ahigh-pressure water-ice jet as a new method for removing a worn-out paint coating from the surface of metal parts (including those found in means of transportation) and for preparing the base [...] Read more.

The paper presents the results of investigations into the possibility of using ahigh-pressure water-ice jet as a new method for removing a worn-out paint coating from the surface of metal parts (including those found in means of transportation) and for preparing the base surface for the application of renovation paint coating. Experimental investigations were carried out in four stages, on flat specimens, sized S × H = 75 × 115 mm, cut from sheet metal made of various materials such as steel X5CrNi18-10, PA2 aluminium alloy and PMMA polymethyl methacrylate (plastic). In the first stage, the surfaces of the samples were subjected to observation of surface morphology under a scanning electron microscope, and surface topography (ST) measurements were made on a profilographometer. Two ST parameters were analysed in detail: the maximum height of surface roughness Sz and the arithmetic mean surface roughness Sa. Next, paint coatings were applied to the specimens as a base. In the third stage, the paint coating applied was removed by means of a high-pressure water-ice jet (HPWIJ) by changing the values of the technological parameters, i.e., water jet pressure p_w, dry ice mass flow rate

{\dot{m}}_{L}

, distance between the sprinkler head outlet and the surface being treated (the so-called working jet length) l₂ and spray angle κ for the following constants: the number of TS = 4 holes, water hole diameter φ = 1.2 mm and sprinkler head length L_k = 200 mm. Afterwards, the surface morphology was observed again and the surface topography of the specimen was investigated by measuring selected 3D parameters of the ST structure, Sz and Sa. The results of investigations into the influence of selected HPWIJ treatment parameters on the surface Q_F removal efficiency obtained are also presented. Univariate regression functions were developed for the mean stripping efficiency based on the following: dry ice mass flow rate

{\dot{m}}_{L}

, working jet length l₂ and spray angle κ. Based on these functions, the values of optimal parameters were determined that allow the maximum efficiency of the process to be obtained. A 95% confidence region for the regression function was also developed. The results demonstrated that HPWIJ treatment does not interfere with the geometric structure of the base material, and they confirmed the possibility of using this treatment as an efficient method of removing a worn paint layer from bases made of various metal and plastic materials, and preparing it for applying a new layer during renovation. Full article

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9 pages, 5330 KiB

Open AccessArticle

Autonomous Design of Photoferroic Ruddlesden-Popper Perovskites for Water Splitting Devices

by Alexandra Craft Ludvigsen, Zhenyun Lan and Ivano E. Castelli

Materials 2022, 15(1), 309; https://doi.org/10.3390/ma15010309 - 2 Jan 2022

Cited by 5 | Viewed by 2550

Abstract

The use of ferroelectric materials for light-harvesting applications is a possible solution for increasing the efficiency of solar cells and photoelectrocatalytic devices. In this work, we establish a fully autonomous computational workflow to identify light-harvesting materials for water splitting devices based on properties [...] Read more.

The use of ferroelectric materials for light-harvesting applications is a possible solution for increasing the efficiency of solar cells and photoelectrocatalytic devices. In this work, we establish a fully autonomous computational workflow to identify light-harvesting materials for water splitting devices based on properties such as stability, size of the band gap, position of the band edges, and ferroelectricity. We have applied this workflow to investigate the Ruddlesden-Popper perovskite class and have identified four new compositions, which show a theoretical efficiency above 5%. Full article

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13 pages, 3182 KiB

Open AccessArticle

The Influence of Specimen Geometry and Loading Conditions on the Mechanical Properties of Porous Brittle Media

by Anatoly M. Bragov, Andrey K. Lomunov, Leonid A. Igumnov, Aleksandr A. Belov and Victor A. Eremeyev

Materials 2021, 14(23), 7144; https://doi.org/10.3390/ma14237144 - 24 Nov 2021

Cited by 1 | Viewed by 1630

Abstract

Dynamic tests of fine-grained fired dioxide-zirconia ceramics under compression under uniaxial stress conditions were carried out. The influence of the specimen length on the obtained strength and deformation properties of ceramics is investigated. The thickness of the specimen has a significant impact on [...] Read more.

Dynamic tests of fine-grained fired dioxide-zirconia ceramics under compression under uniaxial stress conditions were carried out. The influence of the specimen length on the obtained strength and deformation properties of ceramics is investigated. The thickness of the specimen has a significant impact on the course of the obtained dynamic stress–strain diagrams: short specimens have a much more sloping area of active loading branch. The main contribution to the modulus of the load branch resulting from tests of brittle porous media is made by the geometry of the specimens and the porosity of the material. When choosing the length of specimens for dynamic tests, the optimal geometry of the tested specimens is preferable in accordance with the Davies–Hunter criterion, when the contributions of axial and radial inertia are mutually compensated, and the contribution of the effects of friction in the resulting diagram is minimal. When choosing the geometry of specimens of brittle porous media, the structure of the material should be taken into account so that the size of the specimen (both length and diameter) exceeds the size of the internal fractions of the material by at least five times. Full article

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14 pages, 4857 KiB

Open AccessArticle

FDM Layering Deposition Effects on Mechanical Response of TPU Lattice Structures

by Chiara Ursini and Luca Collini

Materials 2021, 14(19), 5645; https://doi.org/10.3390/ma14195645 - 28 Sep 2021

Cited by 19 | Viewed by 3981

Abstract

Nowadays, fused deposition modeling additive technology is becoming more and more popular in parts manufacturing due to its ability to reproduce complex geometries with many different thermoplastic materials, such as the TPU. On the other hand, objects obtained through this technology are mainly [...] Read more.

Nowadays, fused deposition modeling additive technology is becoming more and more popular in parts manufacturing due to its ability to reproduce complex geometries with many different thermoplastic materials, such as the TPU. On the other hand, objects obtained through this technology are mainly used for prototyping activities. For this reason, analyzing the functional behavior of FDM parts is still a topic of great interest. Many studies are conducted to broaden the spectrum of materials used to ensure an ever-increasing use of FDM in various production scenarios. In this study, the effects of several phenomena that influence the mechanical properties of printed lattice structures additively obtained by FDM are evaluated. Three different configurations of lattice structures with designs developed from unit cells were analyzed both experimentally and numerically. As the main result of the study, several parameters of the FDM process and their correlation were identified as possible detrimental factors of the mechanical properties by about 50% of the same parts used as isotropic cell solids. The best parameter configurations in terms of mechanical response were then highlighted by numerical analysis. Full article

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11 pages, 2719 KiB

Open AccessArticle

Phonon Transport and Thermoelectric Properties of Imidazole-Graphyne

by Yanyan Chen, Jie Sun, Wei Kang and Qian Wang

Materials 2021, 14(19), 5604; https://doi.org/10.3390/ma14195604 - 27 Sep 2021

Cited by 4 | Viewed by 2491

Abstract

The pentagon has been proven to be an important structural unit for carbon materials, leading to different physical and chemical properties from those of hexagon-based allotropes. Following the development from graphene to penta-graphene, a breakthrough has very recently been made for graphyne—for example, [...] Read more.

The pentagon has been proven to be an important structural unit for carbon materials, leading to different physical and chemical properties from those of hexagon-based allotropes. Following the development from graphene to penta-graphene, a breakthrough has very recently been made for graphyne—for example, imidazole-graphyne (ID-GY) was formed by assembling experimentally synthesized pentagonal imidazole molecules and acetylenic linkers. In this work, we study the thermal properties and thermoelectric performance of ID-GY by combining first principle calculations with the Boltzmann transport theory. The calculated lattice thermal conductivity of ID-GY is 10.76 W/mK at 300 K, which is only one tenth of that of γ-graphyne (106.24 W/mK). A detailed analysis of the harmonic and anharmonic properties, including the phonon group velocity, phonon lifetime, atomic displacement parameter, and bond energy curves, reveals that the low lattice thermal conductivity can be attributed to the low Young’s modulus, low Debye temperature, and high Grüneisen parameter. Furthermore, at room temperature, ID-GY can reach a high ZT value of 0.46 with a 5.8 × 10¹² cm⁻² hole concentration, which is much higher than the value for many other carbon-based materials. This work demonstrates that changing structural units from hexagonal to pentagonal can significantly reduce the lattice thermal conductivity and enhance the thermoelectric performance of carbon-based materials. Full article

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23 pages, 10365 KiB

Open AccessArticle

Numerical Reliability Study Based on Rheological Input for Bingham Paste Pumping Using a Finite Volume Approach in OpenFOAM

by Robin De Schryver, Khadija El Cheikh, Karel Lesage, Mert Yücel Yardimci and Geert De Schutter

Materials 2021, 14(17), 5011; https://doi.org/10.3390/ma14175011 - 2 Sep 2021

Cited by 10 | Viewed by 2472

Abstract

Rheological quantification is important in many industries, the concrete industry in particular, e.g., pumping, form filling, etc. Instead of performing expensive and time-consuming experiments, numerical simulations are a powerful means in view of rheological assessment. However, due to the unclear numerical reliability and [...] Read more.

Rheological quantification is important in many industries, the concrete industry in particular, e.g., pumping, form filling, etc. Instead of performing expensive and time-consuming experiments, numerical simulations are a powerful means in view of rheological assessment. However, due to the unclear numerical reliability and the uncertainty of rheological input data, it is important for the construction industry to assess the numerical outcome. To reduce the numerical domain of cementitious suspensions, we assessed the numerical finite volume simulations of Bingham paste pumping flows in OpenFOAM. We analysed the numerical reliability, first, irrespective of its rheological input by comparison with the literature and theory, and second, dependent on a certain rheological quantification by comparison with pumping experiments. Irrespective of the rheological input, the numerical results were significantly accurate. Dependent on the rheological input, a numerical mismatch, however, existed. Errors below

1 %

can be expected for proposed numerical rules of thumb: a bi-viscous regularisation, with pressure numbers higher than

5 / 4

. To improve bias due to uncertain rheology, a rheological configuration close to the engineer’s aimed application should be used. However, important phenomena should not be overlooked. Further assessment for lubrication flows, in, e.g., concrete pumping, is still necessary to address concerns of reliability and stability. Full article

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20 pages, 6189 KiB

Open AccessArticle

The Kinematics of Scale Deflection in the Course of Multi-Step Seed Extraction from European Larch Cones (Larix decidua Mill.) Taking into Account Their Cellular Structure

by Ewa Tulska, Monika Aniszewska and Arkadiusz Gendek

Materials 2021, 14(17), 4913; https://doi.org/10.3390/ma14174913 - 29 Aug 2021

Cited by 4 | Viewed by 2177

Abstract

The objective of the study was to elucidate the kinematics of cone opening in the European larch (Larix decidua Mill.) during a four-step seed extraction process and to determine optimum process time on that basis. Each step lasted 8 h with 10 [...] Read more.

The objective of the study was to elucidate the kinematics of cone opening in the European larch (Larix decidua Mill.) during a four-step seed extraction process and to determine optimum process time on that basis. Each step lasted 8 h with 10 min of water immersion between the steps. The study also described the microscopic cellular structure of scales in cones with a moisture content of 5% and 20%, as well as evaluated changes in cell wall thickness. The obtained results were compared with the structural investigations of scales conducted using scanning electron microscopy (SEM) of characteristic sites on the inner and outer sides of the scales. The greatest increment in the scale opening angle was noted on the first day of the process (34°) and in scales from the middle cone segment (39°). In scales with a moisture content of 5% and 20%, the greatest changes in cell wall thickness were recorded for large cells (57%). The inner and outer structure of scales differed in terms of the presence and size of cells depending on the moisture content of the cones (5%, 10%, or 20%). The study demonstrated that the moisture content of cones was the crucial determinant of the cellular structure and opening of scales in larch cones. The scale opening angle increased with decreasing moisture content but did not differ significantly for various segments of cones or various hours of the consecutive days of the process. This finding may lead to reducing the seed extraction time for larch cones. The internal and external structure of scales differed depending on moisture content, which also determined the size and wall thickness of cells. Full article

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13 pages, 1885 KiB

Open AccessArticle

Influence of the Die Height on the Density of the Briquette Produced from Shredded Logging Residues

by Tomasz Nurek, Arkadiusz Gendek and Magdalena Dąbrowska

Materials 2021, 14(13), 3698; https://doi.org/10.3390/ma14133698 - 1 Jul 2021

Cited by 5 | Viewed by 1763

Abstract

An alternative to plant biomass of various origins are forest logging residues. They differ significantly from other, previously used plant materials. This difference is due to the heterogeneous composition and relatively large size of individual particles. This research on the compaction of this [...] Read more.

An alternative to plant biomass of various origins are forest logging residues. They differ significantly from other, previously used plant materials. This difference is due to the heterogeneous composition and relatively large size of individual particles. This research on the compaction of this type of shredded material was aimed at determining the influence of the die height on the density and relaxation of briquettes. This parameter is crucial for the proper construction of compaction devices. The measurements were carried out for the same fractional composition of the shredded logging residues, with variable input parameters of the material and process. It was found that the briquette density and relaxation are influenced by the die height, as well as the material moisture content and process temperature. The highest density at maximum compaction pressure (1.40 g·cm^–3) was obtained at a moisture content of 16%, temperature of 80 °C, and the lowest die height (195 mm). In the case of the briquette density after ejection from the die, the best results were obtained at the same temperature and die height but at a moisture content of 9%. The tests confirmed that, regardless of the process temperature and material moisture, the briquette density increases as the die height is reduced. The relaxation coefficient of compacted logging residues ranges from 21.7% to 50.1% and depends mainly on the material moisture content and the temperature of the process. The lowest value of the relaxation coefficient (21.7 ± 1.61) was obtained at 9% moisture content, 60 °C temperature, and 220 mm die height. Full article

(This article belongs to the Special Issue Feature Papers in Materials Simulation and Design)

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