Materials

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24 pages, 11690 KiB

Open AccessEditor’s ChoiceArticle

Crashworthiness of Additively Manufactured Auxetic Lattices: Repeated Impacts and Penetration Resistance

by Paolo Franzosi, Ivan Colamartino, Alessandro Giustina, Marco Anghileri and Marco Boniardi

Materials 2024, 17(1), 186; https://doi.org/10.3390/ma17010186 - 29 Dec 2023

Cited by 1 | Viewed by 801

Auxetic materials have recently attracted interest in the field of crashworthiness thanks to their peculiar negative Poisson ratio, leading to densification under compression and potentially being the basis of superior behavior upon impact with respect to conventional cellular cores or standard solutions. However, [...] Read more.

Auxetic materials have recently attracted interest in the field of crashworthiness thanks to their peculiar negative Poisson ratio, leading to densification under compression and potentially being the basis of superior behavior upon impact with respect to conventional cellular cores or standard solutions. However, the empirical demonstration of the applicability of auxeticity under impact is limited for most known geometries. As such, the present work strives to advance the investigation of the impact behavior of auxetic meta-materials: first by selecting and testing representative specimens, then by proceeding with an experimental and numerical study of repeated impact behavior and penetration resistance, and finally by proposing a new design of a metallic auxetic absorber optimized for additive manufacturing and targeted at high-performance crash applications. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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16 pages, 9898 KiB

Open AccessArticle

Mechanical Characterisation of Bond Formation during Overprinting of PEEK Laminates

by Simon Hümbert, Fynn Atzler and Heinz Voggenreiter

Materials 2024, 17(1), 161; https://doi.org/10.3390/ma17010161 - 28 Dec 2023

Viewed by 754

Abstract

The latest generation of high-temperature 3D printers enables the production of complex structural components from aerospace-grade thermoplastics such as PEEK (polyether ether ketone). However, adding long or continuous fibres is currently limited, and thermal stresses introduced during the process restrict the maximum part [...] Read more.

The latest generation of high-temperature 3D printers enables the production of complex structural components from aerospace-grade thermoplastics such as PEEK (polyether ether ketone). However, adding long or continuous fibres is currently limited, and thermal stresses introduced during the process restrict the maximum part dimensions. Combining 3D-printed components with continuous fibre-reinforced components into one hybrid structure has the potential to overcome such limitations. This work aims to determine whether in situ bonding between PEEK laminates and PEEK 3D printing during overprinting is feasible and which process parameters are significantly responsible for the bonding quality. To this end, the bonding is analysed experimentally in two steps. Firstly, the influence of the process parameters on the thermal history and the strength of the bond is investigated. In the second step, a detailed investigation of the most critical parameters is carried out. The investigation showed the feasibility of overprinting with bonding strengths of up to 15 MPa. It was shown that the bonding strength depends primarily on the temperature in the interface. Additionally, the critical parameters to control the process were identified. The process influences that were displayed form the basis for future hybrid component and process designs. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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20 pages, 9877 KiB

Open AccessArticle

Composite Medical Tabletops Made of CFRP with Different Cross-Sections: Numerical Analysis and Laboratory Testing

by Przemysław Golewski, Daniel Pietras, Tomasz Sadowski and Albin Michał Wit-Rusiecki

Materials 2023, 16(24), 7574; https://doi.org/10.3390/ma16247574 - 09 Dec 2023

Viewed by 611

Abstract

This paper presents the results of laboratory tests of CFRP (carbon fiber-reinforced polymer) laminates, which allowed the development of numerical material models. The obtained data were used in a further stage to perform numerical simulations of four variants of medical tabletops, differing, among [...] Read more.

This paper presents the results of laboratory tests of CFRP (carbon fiber-reinforced polymer) laminates, which allowed the development of numerical material models. The obtained data were used in a further stage to perform numerical simulations of four variants of medical tabletops, differing, among other features, in the shape of the cross-section. Maximum deflections and effort in the composite material were analyzed. The final step was to perform a laboratory test for one of the tabletop versions, the results of which confirmed the correctness of the numerical calculations. This work is aimed at both researchers and designers involved in the practical application of fiber-reinforced polymer matrix composites. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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15 pages, 3675 KiB

Open AccessArticle

Assessing Effects of van der Waals Corrections on Elasticity of Mg₃Bi_2−xSb_x in DFT Calculations

by Qing Peng, Xinjie Ma, Xiaoyu Yang, Shuai Zhao, Xiaoze Yuan and Xiaojia Chen

Materials 2023, 16(19), 6482; https://doi.org/10.3390/ma16196482 - 29 Sep 2023

Cited by 1 | Viewed by 1068

Abstract

As a promising room-temperature thermoelectric material, the elastic properties of Mg₃Bi_2−xSb_x (0 ≤ x ≤ 2), in which the role of van der Waals interactions is still elusive, were herein investigated. We assessed the effects of two typical [...] Read more.

As a promising room-temperature thermoelectric material, the elastic properties of Mg₃Bi_2−xSb_x (0 ≤ x ≤ 2), in which the role of van der Waals interactions is still elusive, were herein investigated. We assessed the effects of two typical van der Waals corrections on the elasticity of Mg₃Bi_2−xSb_x nanocomposites using first-principles calculations within the frame of density functional theory. The two van der Waals correction methods, PBE-D3 and vdW-DFq, were examined and compared to PBE functionals without van der Waals correction. Interestingly, our findings reveal that the lattice constant of the system shrinks by approximately 1% when the PBE-D3 interaction is included. This leads to significant changes in certain mechanical properties. We conducted a comprehensive assessment of the elastic performance of Mg₃Bi_2−xSb_x, including Young’s modulus, Poisson’s ratio, bulk modulus, etc., for different concentration of Sb in a 40-atom simulation box. The presence or absence of van der Waals corrections does not change the trend of elasticity with respect to the concentration of Sb; instead, it affects the absolute values. Our investigation not only clarifies the influence of van der Waals correction methods on the elasticity of Mg₃Bi_2−xSb_x, but could also help inform the material design of room-temperature thermoelectric devices, as well as the development of vdW corrections in DFT calculations. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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19 pages, 19609 KiB

Open AccessArticle

Crash Performance of Inward-Inverting Composite Tubes Filled with Foam: Experimentation and Simulation

by Pu Yu, Zhefeng Yu, Xiang Zhou and Wu Xu

Materials 2023, 16(19), 6378; https://doi.org/10.3390/ma16196378 - 24 Sep 2023

Viewed by 723

Abstract

This study presents a novel shock absorber with an inward-inverting composite foam-filled tube. Under the compression of a pressing cap and the action of an internal inversion cap, the composite tube inverted inward. During the crushing, the fronds of the composite tube compacted [...] Read more.

This study presents a novel shock absorber with an inward-inverting composite foam-filled tube. Under the compression of a pressing cap and the action of an internal inversion cap, the composite tube inverted inward. During the crushing, the fronds of the composite tube compacted the foam, thereby enhancing the energy absorption. Three types of foams were applied to the absorber, and a drop-weight impact test was performed to obtain the assessment parameters. The foam increased the specific energy absorption (SEA) of the composite tube to 103 kJ/kg. Finite-element simulation based on the user-defined material subroutine was performed for the initial failure and stable stages of the crushing, and a foam model was identified through the experimental data. The mean crush force from the simulation agreed with the experimental data, and the SEA maximum error was <7%, thus validating the crush simulation of the proposed shock absorber. The development of the damage modes of the plies was analyzed based on the simulation results, showing a good energy absorption mechanism of this shock absorber. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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15 pages, 7426 KiB

Open AccessArticle

Filament-Reinforced 3D Printing of Clay

by Julian Jauk, Lukas Gosch, Hana Vašatko, Markus Königsberger, Johannes Schlusche and Milena Stavric

Materials 2023, 16(18), 6253; https://doi.org/10.3390/ma16186253 - 17 Sep 2023

Cited by 1 | Viewed by 1322

Abstract

This research resulted in the development of a method that can be used for filament-reinforced 3D printing of clay. Currently, clay-based elements are mixed with randomly dispersed fibrous materials in order to increase their tensile strength. The advantages of taking this new approach [...] Read more.

This research resulted in the development of a method that can be used for filament-reinforced 3D printing of clay. Currently, clay-based elements are mixed with randomly dispersed fibrous materials in order to increase their tensile strength. The advantages of taking this new approach to create filament-reinforced prints are the increased bridging ability while printing, the increased tensile strength of the dried elements, and the achievement of non-catastrophic failure behavior. The research methodology used involves the following steps: (1) evaluating properties of various filament materials with respect to multiple criteria, (2) designing a filament guiding nozzle for co-extrusion, and (3) conducting a comprehensive testing phase for the composite material. This phase involves comparisons of bridging ability, tensile strength evaluations for un-reinforced clay prints and filament-reinforced prints, as well as the successful production of an architectural brick prototype. (4) Finally, the gathered results are subjected to thorough analysis. Compared to conventional 3D printing of clay, the developed method enables a substantial increase in bridging distance during printing by a factor of 460%. This capability facilitates the design of objects characterized by reduced solidity and the attainment of a more open, lightweight, and net-like structure. Further, results show that the average tensile strength of the reinforced sample in a dry state exhibited an enhancement of approximately 15%. The combination of clay’s ability to resist compression and the filament’s capacity to withstand tension has led to the development of a structural concept in this composite material akin to that of reinforced concrete. This suggests its potential application within the construction industry. Producing the prototype presented in this research would not have been possible with existing 3D printing methods of clay. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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19 pages, 8898 KiB

Open AccessArticle

Increasing the Compressive Strength of Helicoidal Laminates after Low-Velocity Impact upon Mixing with 0° Orientation Plies and Its Analysis

by Zhefeng Yu, Xin Du, Rui Liu, Qiwu Xie, Xiaojing Zhang and Qiao Zhu

Materials 2023, 16(13), 4599; https://doi.org/10.3390/ma16134599 - 26 Jun 2023

Cited by 2 | Viewed by 1116

Abstract

The helicoidal laminate is a kind of nature inspired fiber reinforced polymer, and the ply orientation affects their mechanical properties for engineering structural applications. A variety of helicoidal laminates with uniform and non-linear pitch angles mixed with additional 0° plies are fabricated to [...] Read more.

The helicoidal laminate is a kind of nature inspired fiber reinforced polymer, and the ply orientation affects their mechanical properties for engineering structural applications. A variety of helicoidal laminates with uniform and non-linear pitch angles mixed with additional 0° plies are fabricated to investigate the impact resistance through low-velocity impact and after-impact compression tests. Additionally, helicoidal laminates with constant pitch angles, quasi-isotropic laminate, and cross-ply laminates are also fabricated for a comparative study. The impact characteristics and the compressive strength are analyzed in view of the impact model, shear stress distribution, and fracture toughness. The results suggest that 10° or 20° are the better basic pitch angles before mixing 0° orientation plies. The 0° orientation plies may affect the contact stiffness, bending stiffness, damage extent, and compressive modulus. The compressive strength reaches the highest in tests on two samples with different percentages of 0° orientation plies and ply setups. Bending stiffness also dominates the impact response. The analysis on the laminate parameters provides ideas to improve the residual strength of helicoidal laminate. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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17 pages, 2243 KiB

Open AccessArticle

Optimization Design and Nonlinear Bending of Bio-Inspired Helicoidal Composite Laminated Plates

by Taoye Lu, Hui-Shen Shen, Hai Wang, Xiuhua Chen and Miaolin Feng

Materials 2023, 16(13), 4550; https://doi.org/10.3390/ma16134550 - 23 Jun 2023

Cited by 3 | Viewed by 730

Abstract

Inspired by the bionic Bouligand structure, helicoidal carbon fiber-reinforced polymer composite (CFRPC) laminates have been proven to own outstanding out-of-plane mechanical properties. This work aims to further explore the excellent bending characteristics of helicoidal CFRPC laminated plates and find out the optimal helicoidal [...] Read more.

Inspired by the bionic Bouligand structure, helicoidal carbon fiber-reinforced polymer composite (CFRPC) laminates have been proven to own outstanding out-of-plane mechanical properties. This work aims to further explore the excellent bending characteristics of helicoidal CFRPC laminated plates and find out the optimal helicoidal layup patterns. The optimization design of laminated plates stacked with single-form and combination-form helicoidal layup sequences are carried out by using the finite element method (FEM) and adaptive simulated annealing (ASA) optimization algorithm on the Isight platform. Then, the nonlinear bending responses of optimal helicoidal CFRPC laminated plates are investigated via the FEM for the first time. The helicoidal CFRPC laminated plates under three different types of boundary conditions subjected to transverse uniformly distributed load are considered. The numerical results reveal that the combination-form helicoidal layup sequences can decrease the dimensionless bending deflection of laminated plates by more than 5% compared with the quasi-isotropic plate and enhance the out-of-plane bending characteristics of CFRPC laminated plates effectively. The boundary conditions can significantly influence the nonlinear bending responses of helicoidal CFRPC laminated plates. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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15 pages, 7067 KiB

Open AccessArticle

Study of Hybrid Composite Joints with Thin-Ply-Reinforced Adherends

by Farin Ramezani, Ricardo J. C. Carbas, Eduardo A. S. Marques and Lucas F. M. da Silva

Materials 2023, 16(11), 4002; https://doi.org/10.3390/ma16114002 - 26 May 2023

Viewed by 1075

Abstract

It has been demonstrated that a possible solution to reducing delamination in a unidirectional composite laminate lies in the replacement of conventional carbon-fibre-reinforced polymer layers with optimized thin-ply layers, thus creating hybrid laminates. This leads to an increase in the transverse tensile strength [...] Read more.

It has been demonstrated that a possible solution to reducing delamination in a unidirectional composite laminate lies in the replacement of conventional carbon-fibre-reinforced polymer layers with optimized thin-ply layers, thus creating hybrid laminates. This leads to an increase in the transverse tensile strength of the hybrid composite laminate. This study investigates the performance of a hybrid composite laminate reinforced by thin plies used as adherends in bonded single lap joints. Two different composites with the commercial references Texipreg HS 160 T700 and NTPT-TP415 were used as the conventional composite and thin-ply material, respectively. Three configurations were considered in this study: two reference single lap joints with a conventional composite or thin ply used as the adherends and a hybrid single lap. The joints were quasi-statically loaded and recorded with a high-speed camera, allowing for the determination of damage initiation sites. Numerical models of the joints were also created, allowing for a better understanding of the underlying failure mechanisms and the identification of the damage initiation sites. The results show a significant increase in tensile strength for the hybrid joints compared to the conventional ones as a result of changes in the damage initiation sites and the level of delamination present in the joint. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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27 pages, 26323 KiB

Open AccessArticle

Effect of Al₂O₃ (x = 0, 1, 2, and 3 vol.%) in CrFeCuMnNi-x High-Entropy Alloy Matrix Composites on Their Microstructure and Mechanical and Wear Performance

by S. Sivasankaran, Hany R. Ammar, El-Sayed M. Sherif, Abdulaziz S. Alaboodi and Abdel-baset H. Mekky

Materials 2023, 16(10), 3672; https://doi.org/10.3390/ma16103672 - 11 May 2023

Viewed by 1233

Abstract

This work aims to study the influence of Al₂O₃ in CrFeCuMnNi high-entropy alloy matrix composites (HEMCs) on their microstructure, phase changes, and mechanical and wear performances. CrFeCuMnNi-Al₂O₃ HEMCs were synthesized via mechanical alloying (MA) followed by hot [...] Read more.

This work aims to study the influence of Al₂O₃ in CrFeCuMnNi high-entropy alloy matrix composites (HEMCs) on their microstructure, phase changes, and mechanical and wear performances. CrFeCuMnNi-Al₂O₃ HEMCs were synthesized via mechanical alloying (MA) followed by hot compaction (550 °C at 550 MPa), medium frequency sintering (1200 °C), and hot forging (1000 °C at 50 MPa). The XRD results demonstrate the formation of both FCC and BCC phases in the synthesized powders, which were transformed into major stable FCC and minor ordered B2-BCC phases, as confirmed by HRSEM. The microstructural variation of HRSEM-EBSD, in terms of the coloured grain map (inverse pole figures), grain size distribution, and misorientation angle, was analysed and reported. The grain size of the matrix decreased with the increase in Al₂O₃ particles owing to the higher structural refinement by MA and zener pinning of the incorporated Al₂O₃ particles. The hot-forged CrFeCuMnNi-3 vol.% Al₂O₃ sample exhibited an ultimate compressive strength of 1.058 GPa, which was 21% higher than that of the unreinforced HEA matrix. Both the mechanical and wear performance of the bulk samples increased with an increase in Al₂O₃ content due to solid solution formation, high configurational mixing entropy, structural refinement, and the effective dispersion of the incorporated Al₂O₃ particles. The wear rate and coefficient of friction values decreased with the increase in Al₂O₃ content, indicating an improvement in wear resistance owing to the lower domination of abrasive and adhesive mechanisms, as evidenced by the SEM worn surface morphology. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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15 pages, 2405 KiB

Open AccessArticle

Chirality-Dependent and Intrinsic Auxeticity for Single-Walled Carbon Nanotubes

by Hai-Ning Zhang, Yin Fan and Hui-Shen Shen

Materials 2022, 15(24), 8720; https://doi.org/10.3390/ma15248720 - 07 Dec 2022

Cited by 4 | Viewed by 2239

Abstract

Single-walled carbon nanotubes (SWCNTs) have superior mechanical properties which originate from a strong C-C covalent bond and unique nanostructure. Chirality, one of the helical structural parameters of SWCNTs, leads to differences in mechanical performance. In this work, molecular dynamics (MD) simulation was performed [...] Read more.

Single-walled carbon nanotubes (SWCNTs) have superior mechanical properties which originate from a strong C-C covalent bond and unique nanostructure. Chirality, one of the helical structural parameters of SWCNTs, leads to differences in mechanical performance. In this work, molecular dynamics (MD) simulation was performed to analyze engineering Poisson’s ratio (EPR) and incremental Poisson’s ratio (IPR) of SWCNTs with different chiral angles, respectively, under tensile and compressive load, as well as the chiral effect on rigidity. We reported the minimum EPR for (4, 1) SWCNT and obtained the distribution and trend of EPR which is dependent on chiral index m. In addition, a new observation showed two exactly opposite trends of EPR existing not only in tension and compression but also in the longitudinal and radial directions. Furthermore, we found that the critical strain, over which SWCNT would be auxetic, ranged from 6% to 18% and was also chirality-dependent. Three representative SWCNTs with chiral angle of 0° (zigzag), 10.89° (chiral), and 30° (armchair) were selected for the mechanism study of auxeticity. Finally, a method of the contribution to radial strain for two main deformation modes proposed in this paper could well explain the negative IPR phenomenon. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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17 pages, 3972 KiB

Open AccessArticle

Auxetic Composite Laminates with Through-Thickness Negative Poisson’s Ratio for Mitigating Low Velocity Impact Damage: A Numerical Study

by Yeqing Wang

Materials 2022, 15(19), 6963; https://doi.org/10.3390/ma15196963 - 07 Oct 2022

Cited by 9 | Viewed by 1894

Abstract

Auxetic materials are those that exhibit negative Poisson’s ratios. Such a unique property was shown to improve the indentation and impact resistances. Angle-ply composite laminates can be designed to produce negative Poisson’s ratio at the laminate level due to the large anisotropicity of [...] Read more.

Auxetic materials are those that exhibit negative Poisson’s ratios. Such a unique property was shown to improve the indentation and impact resistances. Angle-ply composite laminates can be designed to produce negative Poisson’s ratio at the laminate level due to the large anisotropicity of the individual layer and the strain mismatch between adjacent layers. This paper investigates the effect of through-thickness negative Poisson’s ratio on the low velocity impact behaviors of carbon fiber reinforced polymer matrix composite laminates, including the global impact behaviors, as well as the delamination, and the fiber and matrix damage. Results from numerical investigations show consistently reduced fiber and matrix tensile damage in the auxetic laminate in all plies, in comparison to the non-auxetic counterpart laminates (up to 40% on average). However, the auxetic laminate does not present a clear advantage on mitigating the delamination damage or the matrix compressive damage. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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15 pages, 7011 KiB

Open AccessArticle

Novel Alumina Matrix Composites Reinforced with MAX Phases—Microstructure Analysis and Mechanical Properties

by Mateusz Petrus, Jaroslaw Wozniak, Tomasz Cygan, Wojciech Pawlak and Andrzej Olszyna

Materials 2022, 15(19), 6909; https://doi.org/10.3390/ma15196909 - 05 Oct 2022

Cited by 5 | Viewed by 1263

Abstract

This article describes the manufacturing of alumina composites with the addition of titanium aluminum carbide Ti₃AlC₂, known as MAX phases. The composites were obtained by the powder metallurgy technique with three types of mill (horizontal mill, attritor mill, and [...] Read more.

This article describes the manufacturing of alumina composites with the addition of titanium aluminum carbide Ti₃AlC₂, known as MAX phases. The composites were obtained by the powder metallurgy technique with three types of mill (horizontal mill, attritor mill, and planetary mill), and were consolidated with the use of the Spark Plasma Sintering method at 1400 °C, with dwelling time 10 min. The influence of the Ti₃AlC₂ MAX phase addition on the microstructure and mechanical properties of the obtained composites was analyzed. The structure of the MAX phase after the sintering process was also investigated. The chemical composition and phase composition analysis showed that the Ti₃AlC₂ addition preserved its structure after the sintering process. The increase in fracture toughness for all series of composites has been noted (over 20% compared to reference samples). Detailed stereological analysis of the obtained microstructures also could determine the influence of the applied mill on the homogeneity of the final microstructure and the properties of obtained composites. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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30 pages, 100221 KiB

Open AccessArticle

Tests and Numerical Study of Single-Lap Thermoplastic Composite Joints Bolted by Countersunk

by Jian Zhang, Xiuhua Chen, Aiqin Tian and Yin Fan

Materials 2022, 15(7), 2386; https://doi.org/10.3390/ma15072386 - 24 Mar 2022

Cited by 1 | Viewed by 1808

Abstract

Tensile tests were carried out to investigate the effect of stacking sequences on the bearing strength of single-lap thermoplastic composite countersunk bolted joints. A 3D elastoplastic model was built based on a plastic theory for numerical analysis. The damage initiation was judged based [...] Read more.

Tensile tests were carried out to investigate the effect of stacking sequences on the bearing strength of single-lap thermoplastic composite countersunk bolted joints. A 3D elastoplastic model was built based on a plastic theory for numerical analysis. The damage initiation was judged based on LaRC05 criteria, and the damage propagation was described by using a nonlinear, gradual unloading method based on crack band theory. The accuracy of the present model was validated by comparing the numerical results to those from the tests. The test results showed that the effects of stacking sequences on the ultimate bearing strength and the 2% offset bearing strength are limited. Moreover, the numerical results depicted that the ultimate bearing strength and the 2% offset bearing strength reduce when the bolt-tightening torque or the bolt–hole clearance is increased. Full article

(This article belongs to the Special Issue Mechanical Performance of Advanced Composite Materials and Structures)

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