Superior Specific Strength Research Articles

Preparation of a novel high-entropy alloy AlNbTiVZr with excellent strength and ductility: The effect of Zr composition on microstructure and properties

Light-weight refractory high-entropy alloys with low density and good ductility are widely used in various engineering fields. Despite their potential, achieving an optimal strength-ductility balance in these lightweight alloys remains an emerging field of study. In this study, Al0.8Nb0.5Ti2V2Zrx (x = 0, 0.3, 0.6, and 0.9) alloys were prepared by vacuum arc melting. A comprehensive evaluation of their microstructure, density, hardness, and compressive behavior at both room and 873 K temperatures was conducted. The introduction of Zr transforms the alloy phase structure from body-centered cubic (BCC) to BCC + C14-Laves. The areal fraction of the C14-Laves phase increased from 0 % to 32.47 % with increasing Zr content from x = 0 to 0.9, respectively. Furthermore, the Zr content had an obvious effect on the mechanical properties of the alloys. The compressive strength and hardness of the alloys improved, but the ductility simultaneously decreased, with increasing Zr content. The yield strengths of the alloys with x = 0, 0.3, 0.6, and 0.9 reached 971, 1216, 1483, and 1714 MPa, respectively, at room temperature, and 946, 1287, 1319, and 1469 MPa, respectively, at 873 K. In addition, the alloys maintained their deformation resistance and good ductility at 873 K. In particular, the Al0.8Nb0.5Ti2V2Zr0.3 exhibited a good balance between strength and ductility at room and 873 K temperatures due to the strengthening effect of a granular secondary phase. Upon comparison with other reported high-entropy alloys, the Al0.8Nb0.5Ti2V2Zrx series showcased superior specific yield strength and ductility.

Unveiling micro-scale mechanisms of in-situ silicon alloying for tailoring mechanical properties in titanium alloys: Experiments and computational modeling

Titanium-silicon (Ti-Si) alloy system shows significant potential for aerospace and automotive applications due to its superior specific strength, creep resistance, and oxidation resistance. For Si-containing Ti alloys, the sufficient content of Si is critical for achieving these favorable performances, while excessive Si addition will result in mechanical brittleness. Herein, both physical experiments and finite element (FE) simulations are employed to investigate the micro-mechanisms of Si alloying in tailoring the mechanical properties of Ti alloys. Four typical states of Si-containing Ti alloys (solid solution state, hypoeutectoid state, near-eutectoid state, hypereutectoid state) with varying Si content (0.3–1.2 wt.%) were fabricated via in-situ alloying spark plasma sintering. Experimental results indicate that in-situ alloying of 0.6 wt.% Si enhances the alloy's strength and ductility simultaneously due to the formation of fine and uniformly dispersed Ti5Si3 particles, while higher content of Si (0.9 and 1.2 wt.%) results in coarser primary Ti5Si3 agglomerations, deteriorating the ductility. FE simulations support these findings, highlighting the finer and more uniformly distributed Ti5Si3 particles contribute to less stress concentration and promote uniform deformation across the matrix, while agglomerated Ti5Si3 particles result in increased local stress concentrations, leading to higher chances of particle fracture and reduced ductility. This study not only elucidates the micro-mechanisms of in-situ Si alloying for tailoring the mechanical properties of Ti alloys but also aids in optimizing the design of high-performance Ti alloys.

Design and characterization of novel Ti-8Mo-xFe-yCu alloys as implant materials: Evaluation of biocompatibility, mechanical properties, and antibacterial potential

Titanium and its alloys are highly desirable materials for biomedical metallic implants due to their superior specific strength, excellent corrosion resistance, and exceptional biocompatibility. Among these alloys, Ti6Al4V is widely used in practical biomedical applications because it offers an excellent combination of strength, fracture toughness, and corrosion resistance. However, recent research has revealed limitations in its biocompatibility attributed to the presence of toxic elements such as Al and V. In addition, it has been reported that Ti6Al4V is costly due to the addition of Vanadium and has the potential for post-implant inflammation. As a result, researchers have been investigating new biomedical beta-Ti alloys using biocompatible, affordable, and easily accessible beta-stabilizers like Mo, Fe, and Cu, to achieve similar performance as Ti6Al4V alloys. The present study aims to develop a novel biomedical alloy through the arc melting method, to obtain an implant material possessing low elastic moduli, biocompatibility, and antibacterial properties to mitigate the risk of post-implant inflammation. Microstructural analysis was conducted using microscopy and x-ray diffraction, while the mechanical properties were evaluated through micro vickers hardness testing machine and elastic moduli measurement utilizing the impulse excitation technique. Cytotoxicity assessment was performed using the (Cell Counting Kit-8) CCK-8 method, followed by an examination of the alloy's antibacterial properties using the point counting method. β-Ti single phase was obtained in this study with the addition of ≥1% Fe and ≥1% Cu. The Ti-8Mo-2Fe-2Cu alloy was found to have the lowest elastic moduli of 95 GPa. Electrochemical measurements show that the Ti-8Mo- xFe- yCu alloys have a lower corrosion current density of around 0.319–2.317 µA/cm2 compared to Ti6Al4V of 16.543 µA/cm2. The Ti-8Mo-1Fe-3Cu, Ti-8Mo-3Fe-1Cu, and Ti-8Mo-3Fe-3Cu alloys have comparable biocompatibility with Ti6Al4V with the viability of mesenchymal stem cells (MSCs) above 75% and have a positive antibacterial response. Ti-8Mo-3Fe-3Cu alloy demonstrates the most favorable blend of microstructure, mechanical attributes, corrosion resistance, cell viability, and antibacterial properties as an alternate biomaterial for implant applications.

Optimization of Machining Process on Coated Tungsten Carbide Electrode Tool and Titanium Alloy Workpiece Using EDM: A Critical Review

Commercial applications for Ti 6Al 4V, an alloy composed of titanium, aluminium, and vanadium, are possible. The features of titanium alloy include: Lightweight, non-magnetic, high melting point, outstanding fatigue strength, superior specific strength, great corrosion resistance, and biocompatibility. Reviewing the electro-discharge machining of titanium alloy (Ti 6Al 4V) as a workpiece, silicon carbide particle combined with EDM oil, and coated tungsten carbide electrode, this research examines this process. Dielectric fluid's impact on microhardness, surface finishing, TWR, and MRR. MRR is raised by silicon particles and coated tungsten carbide electrodes with EDM fluid. According to the study, the most important input parameters for determining TWR, MRR, surface finishing, and micro-hardness are voltage, current, pulse on time (Tonne), and pulse off time (Toff).

Multi-functional hybrid sandwich composite structures: Evaluating damage mechanics and tolerance using compression after impacts

Building upon previous researches that introduced an innovative foam core hybrid-sandwich composite structure for radome applications, showcasing promising performance under low-velocity impacts (LVIs), this paper delves into the assessment of damage tolerance and mechanics through Compression After Impact (CAI) testing. The primary objective is to analyze disparities in damage tolerance, damage mechanisms, displacements, deformations, energy absorption, and residual strengths resulting from LVIs followed by CAIs on dissimilar materials on opposite faces of the hybrid structure. The extent of damage is evaluated through Computed Tomography (CT) scans. During LVIs, impacts on the S glass face sheets side demonstrated different energy dispersion and absorption mechanisms, leading to variations in indent damage depths and widths across all impact energy levels, unlike the impact damages observed from the Kevlar side. During CAI testing, this difference becomes more evident, with Kevlar specimens (KS3 & KS5) showing greater indentation depths and narrower widths, and S glass specimens (SK3 & SK5) experiencing buckling. These effects are due to the unique damage absorption and dispersion properties of Kevlar and S glass. These variations prompted an in-depth investigation of the structure using CAI to comprehend damage tolerance and mechanisms under compressive loads. This study, unparalleled in existing literature, proposes hybrid sandwich structures with superior specific impact and residual strength compared to various composite sandwich structures documented in published literature, expanding their utility beyond radomes.

Empirical and numerical analysis of damage tolerance in multifunctional hybrid sandwich fiber reinforced polymers composite structures for aerospace applications using compression after impact (CAI) testing

AbstractThis study presents a novel hybrid‐sandwich composite structure, customized for nose radomes applications, incorporating a foam core and distinct opposite face sheets composed of Kevlar and S‐Glass materials. Addressing in‐phase electromagnetic properties, UV protection and low velocity impact responses in our previously published work, this paper empirically and numerically investigates the damage tolerance response of the proposed structures through compression after impact (CAI) testing. The low velocity impacts (LVIs) on S‐Glass face sheets exhibited unique energy dispersion and absorption mechanisms, resulting in variations in indent damage depths and widths across all impact energy levels as compared with LVIs on Kevlar face sheets. After experimentally assessing the CAI behavior, a FE model is developed to predict CAI behavior, which closely aligned with experimental findings. This study, unprecedented in existing literature, proposes hybrid sandwich structures for nose radome aerospace applications, with superior specific impact and residual strength compared to various composite sandwich structures documented in the published literature expanding its utility beyond radomes.Highlights Innovative composites with superior low velocity impact response, tested for compression after impact performance. Designed for nose radomes found suitable for other impact prone applications. Experimental and numerical modeling showed comparable results. Major differences observed in damage mechanics, resistance, and tolerances.

Probability Prediction of Curing Process-Induced Deformation for V-Shape Composite Structures Based on FEM Method and Data Mining.

Continuous fiber-reinforced composites are increasingly used in industry for their superior specific modulus and strength. The curing process-induced deformation (PID) has been a critical problem during manufacturing, which always exhibits dispersed values even if the curing process curve and structural parameters remain consistent. This work conducted probability prediction of PID for V-shape composite structures based on the FEM method and data mining. A sequential coupling thermal-chemical-mechanical coupling FE model is established in ABAQUS. The prediction accuracy of the included angle between two sides is verified by the experimental results. Material parameter uncertainties are considered for V-shape structures with different radii and thicknesses. Based on the dataset from the FE model, a decision tree is established and trained to analyze the sensitivity and to predict the probability distribution of PID. The results show that PID increases with the coefficients of thermal expansion in the in-plane perpendicular fiber direction and out-of-plane normal direction. The data-mining method is accurate enough for the PID prediction, and its efficiency provides an additional calculation option in engineering applications.

Effect of Pore Architecture of 3D Printed Open Porosity Cellular Structures on Their Resistance to Mechanical Loading: Part I – Experimental Studies

Abstract The development of additive manufacturing (AM) techniques has sparked interest in porous structures that can be customized in terms of size, shape, and arrangement of pores. Porous lattice structure (LS, called also lattice struct) offer superior specific stiffness and strength, making them ideal components for lightweight products with energy absorption and heat transfer capabilities. They find applications in industries such as aerospace, aeronautics, automotive, and bone ingrowth applications. One of the main advantages of additive manufacturing is the freedom of design, control over geometry and architecture, cost and time savings, waste reduction, and product customization. However, the designation of appropriate struct/pore geometry to achieve the desired properties and structure remains a challenge. In this part of the study, five lattice structs with various pore sizes, with two volume fractions for each, and shapes (ellipsoidal, helical, X-shape, trapezoidal, and triangular) were designed and manufactured using selective laser sintering (SLS) additive manufacturing technology. Mechanical properties were tested through uniaxial compression, and the apparent stress-strain curves were analyzed. The results showed that the compression tests revealed both monotonic and non-monotonic stress-strain curves, indicating different compression behaviors among the structures. The helical structure exhibited the highest resistance to compression, while other structures showed similarities in their mechanical properties. In Part II of this study provides a comprehensive analysis of these findings, emphasizing the potential of purpose-designed porous structures for various engineering applications.

Design, Manufacturing, and Analysis of Periodic Three-Dimensional Cellular Materials for Energy Absorption Applications: A Critical Review.

Cellular materials offer industries the ability to close gaps in the material selection design space with properties not otherwise achievable by bulk, monolithic counterparts. Their superior specific strength, stiffness, and energy absorption, as well as their multi-functionality, makes them desirable for a wide range of applications. The objective of this paper is to compile and present a review of the open literature focusing on the energy absorption of periodic three-dimensional cellular materials. The review begins with the methodical cataloging of qualitative and quantitative elements from 100 papers in the available literature and then provides readers with a thorough overview of the state of this research field, discussing areas such as parent material(s), manufacturing methods, cell topologies, cross-section shapes for truss topologies, analysis methods, loading types, and test strain rates. Based on these collected data, areas of great and limited research are identified and future avenues of interest are suggested for the continued maturation and growth of this field, such as the development of a consistent naming and classification system for topologies; the creation of test standards considering additive manufacturing processes; further investigation of non-uniform and non-cylindrical struts on the performance of truss lattices; and further investigation into the performance of lattice materials under the impact of non-flat surfaces and projectiles. Finally, the numerical energy absorption (by mass and by volume) data of 76 papers are presented across multiple property selection charts, highlighting various materials, manufacturing methods, and topology groups. While there are noticeable differences at certain densities, the graphs show that the categorical differences within those groups have large overlap in terms of energy absorption performance and can be referenced to identify areas for further investigation and to help in the preliminary design process by researchers and industry professionals alike.

Electrochemical investigation of electrophoretically deposited graphene-oxide coating on AZ31 alloy prepared using in-house synthesized few-layer graphene-oxide nanosheets

Magnesium and its alloys possess low density and superior specific strength making it a potential structural metal to be used in different engineering fields. However, its proneness to corrosion limits its applications. In this novel study, an eco-friendly graphene-oxide coating was prepared on AZ31 magnesium alloy via electrophoretic deposition to enhance its anti-corrosion properties. Scanning electron microscopy coupled with energy dispersive spectroscopy, atomic force microscopy, and scratch test were adopted to investigate surface morphology, roughness, chemical composition, and adherence of the coating. The corrosion behaviour of graphene-oxide coated alloy was studied using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt% NaCl and Borate Buffer solutions. The obtained results demonstrate that the coating developed on AZ31 alloy is smooth and adherent with the hardness of the as-deposited coating measuring as high as 6.0 GPa. In addition, the electrochemical corrosion behaviour studies revealed that the coating significantly increased the corrosion potential (Ecorr) of the alloy towards more noble values (−0.65 V < Ecorr < −0.35 V), with the coated alloys possessing a charge transfer resistance nearly two orders of magnitude greater than their non-coated counterparts. Consequently, the corrosion rate of the coated alloy decreased substantially, indicating that the coating exhibits exceptional corrosion resistance (0.045–0.09 mm/a in 3.5 wt% NaCl and 0.002–0.006 mm/a in Borate Buffer). These findings challenge the conventional beliefs that graphene exhibits strong cathodic behaviour towards anodic materials such as AZ31 alloy. Thus, the outcomes not only have the potential to revolutionize the advancement of graphene-oxide coatings for corrosion resistance but could also possibly expand AZ31 alloy’s applications in the aerospace and automotive sectors.

Investigating damage resistance in aerospace radome applications: Experimental analysis of hybrid sandwich composites

This research introduces an innovative hybrid sandwich composite structure tailored for specific applications, featuring a foam core and dissimilar face sheets made of Kevlar and S-Glass materials to address in-phase electromagnetic properties, UV protection, and impact response. Building on our prior work on design optimization for electromagnetic performance and aero/inertial loading, this paper investigates the low-velocity impacts (LVIs) response of the composite structure through drop-weight testing at various energy levels. Utilizing computed tomography (CT) scanning for damage analysis, distinct failure modes were observed for different face sheet combinations, with notable variations (energy absorption characteristics) in damage depth and width between the S-Glass and Kevlar face sheets. This study, unprecedented in existing literature, proposes hybrid sandwich structures with superior specific impact strength compared to various composite sandwich structures documented in the published literature expanding its utility beyond radomes.

Evaluation of True Bonding Strength for Adhesive Bonded Carbon Fiber-Reinforced Plastics.

Carbon fiber-reinforced thermoplastics (CFRTPs) have attracted attention in aerospace because of their superior specific strength and stiffness. It can be assembled by adhesive bonding; however, the existing evaluation of bonding strength is inadequate. For example, in a single-lap shear test, the weld zone fails in a combined stress state because of the bending moment. Therefore, the strength obtained experimentally is only the apparent strength. The true bonding strength was obtained via numerical analysis by outputting the local stress state at the initiation point of failure. In this study, the apparent and true bonding strengths were compared with respect to three types of strength evaluation tests to comprehensively evaluate bonding strength. Consequently, the single-lap shear test underestimates the apparent bonding strength by less than 14% of the true bonding strength. This indicates that care should be taken when determining the adhesion properties for use in numerical analyses based on experimental results. We also discussed the thickness dependence of the adhesive on the stress state and found that the developed shear test by compression reduced the discrepancy between apparent and true strength compared with the single-lap shear test and reduced the thickness dependence compared with the flatwise tensile test.

On the dynamic performance of additively manufactured visco-elastic meta-materials

Additive manufacturing (AM) has revolutionized the production of structures with tailored material properties, including elastomer polyurethanes (EPU) which exhibit exceptional mechanical performance. EPU possesses unique characteristics, such as high elongation at break, efficient energy dissipation, and superior specific strength, making it well-suited for applications requiring resilience to dynamic loadings. By combining the advantages of AM and EPU, enhanced and customized meta-materials can be created, surpassing the mechanical performance of traditional bulk materials. However, because of the non-linear stress–strain response of both the constitutive material and the structure, designing such meta-materials for high strain-rates can be challenging. In this work, therefore, quasi-static and dynamic experiments were conducted to evaluate a meta-material architecture. The investigation revealed a strong positive rate dependency. The mechanical performances, including strength, and dissipated energy, increased with increasing loading rate. The EPU meta-materials demonstrate their suitability for dynamic applications where high energy dissipation is crucial for reducing transmitted loads.

Mechanical properties and failure behaviors of T1100/5405 composite T-joint under in-plane shear load coupled with initial defect and high-temperature

The T1100/5405, a novel carbon fiber resin matrix composite, boasts superior specific strength, stiffness, and broad applicability. This study rigorously investigated the in-plane shear performance and thermally coupled damage failure mechanisms of this composite in a T-joint context under initial defects, being highly relevant for hypersonic vehicles in high-temperature environments. Experimental tests yielded mechanical property parameters and in-plane shear data for varying test temperatures (25℃, 150℃) and defect radius (0 mm, 15 mm). Compared to flawless samples at room temperature, the synergistic impact of high temperature and defects expedited the structural damage failure process, reducing load-bearing capabilities significantly. A numerical model was established based, on the inherent structural relationship of the cohesive zone model and the continuum damage mechanics of the composite, whose accuracy was confirmed by experimental data. Further analysis revealed that a high-temperature environment would exacerbate the damage failure process of initial defects. Specifically, as the temperature rose, the defect radius increased, thus diminishing the shear capacity of T-joint. The maximum structural ultimate load has been reduced by 67.54 %, which was perfectly aligned with experimental results. Consequently, the study provides practical insights for the structural design of hypersonic vehicle composite.

Acid‐Assisted Toughening Aramid Aerogel Monoliths with Ultralow Thermal Conductivity and Superior Tensile Toughness

AbstractResisting extreme loading and thermal ablation encountered by aerospace devices demands for high performance engineering materials. Aerogels have achieved satisfactory thermal insulation but the intrinsic brittleness of porous skeletons fail to ensure their normal operation under severe stress fields. Herein, aramid nanofibers (ANFs) are processed into tough 3D aerogel monoliths via a multi‐scale toughening strategy, involving unidirectional freeze‐casting‐enabled microstructure orientation and acid‐assisted nanofiber cross‐linking. Scalable production of ANFs aerogels is realized through fast air‐drying without excessive energy consumption. The aligned sheets in ANFs aerogels enable extreme thermal conductivity of 15.8 mW m−1 K−1, superinsulation from −130 to 300 °C, and durable combustion protection for 20 min. Particularly, highly aggregated nanofibers assemble into dense ANFs skeletons, endowing the tough aerogels with superior specific tensile strength (89 MPa cm3 g−1), ultra‐high toughness (1.3 MJ m−3), and impressive fracture energy (7.36 kJ m−2). Such mechanical properties are highly resistant to harsh environments, including water erosion (7 days) and high temperature baking (30 days). Moreover, ANFs aerogels exhibit two to three times more energy dissipation than commercial foams against ballistic impact at 140 m s−1. This integrated mechanical and thermal robustness may pioneer the potential application in impact‐thermal coupled safeguard for aerogel materials.

Improved compressive performance of lattice truss core sandwich composites with modified Kagome topologies: An experimental and numerical study

A finite element model (FEM) using a more realistic three-dimensional geometry of lattice truss core was proposed to simulate the flatwise compression test on lattice truss core sandwich composites (LTCSCs). The goal was to reduce the disparity between experimental results and FEM predictions without inclusion of imperfection, as oppose to similar studies. Besides, two modified Kagome topologies were suggested and fabricated by adding vertical composite struts at specific locations. Based on the experimental results, the modified Kagome topologies exhibited superior specific compressive stiffness and strength over the Kagome topology, by about 100%. In addition, facesheet rotation of Kagome topology was found by the FEM, which considerably affect its compressive performance. Facesheet rotation is caused by the arrangement of composite struts of LTCSC. Compressive response of LTCSC was acceptably predicted by the FEM, though there was quite high error for compressive stiffness and strength. Probable sources of discrepancy between experimental and FEM results were discussed.

Experimental investigations into nonlinear dynamic behaviours of triply periodical minimal surface structures

Natural frequency, damping ratio and dynamic stiffness are fundamental to the performance of structures subjected to dynamic loads. Triply Periodic Minimal Surface (TPMS) composite structures, celebrated for their superior energy absorption capacity and specific strength, represent some of the most promising meta-structures. However, their dynamic properties are yet to be fully understood, thereby hindering their practical applications within civil engineering domains. Damping properties, crucial to vibration reduction, remain particularly elusive; previous studies have not successfully established a connection between these properties and the force excitation amplitude in TPMS structures. This study aims to compare the damping properties of different TPMS structures and to investigate their potential for adoption within civil engineering fields. Three types of TPMSs, including Schoen I-graph-wrapped package surface (IWP), Schwarz primitive (Primitive) and Schoen Gyroid (Gyroid), have been adopted to design solid and sheetal TPMS composite structures with identical relative density (50%) to compare their damping properties under varying excitation amplitudes. These TPMS structures are manufactured from photosensitive resin (UV resin) using stereolithography 3D printing technology. Owing to the lack of previous research into the damping properties and dynamic stiffness of TPMS structures as support structures, we have conducted single-freedom modal tests to determine the modal parameters, including natural frequency and damping ratios. Our novel results indicate that the natural frequency and damping ratio of the TPMS structures vary with the excitation amplitude. Additionally, the dynamic stiffness of TPMS structures reveals a similar decreasing trend to frequency when load amplitude escalates. As the excitation amplitude increases, the TPMS structures demonstrate softening and are capable of offering a higher vibration damping coefficient. Notably, the SS-Gyroid structure exhibits higher stiffness and damping ratio compared to other TPMS structures. These fresh insights pave the way for the integration of 3D printed smart TPMS structures within civil engineering, particularly for vibration reduction and efficient material usage. A judicious TPMS structure design can provide relatively high stiffness and damping ratio without excessive material use.

Ultrafast volumetric assembly of layered nanocomposites at dynamic gelation interface

Biomimetic learning has boosted the development of layered nanocomposites with superior mechanical properties, fast ion conduction, high barrier capacities, and high conductivities, resulting in numerous practical applications in artificial structural materials, energy storage, filtration, and electromagnetic shielding. These outstanding properties arise from the highly oriented layered structure. Convenient fabrication and complex shapes are required for practical applications. However, conventional strategies, including ice templating, vacuum filtration, and electromagnetic induction, are constrained by time-consuming fabrication and sample shapes, restricting their extension to large-scale applications. Here, we present a facile, universal, and scalable strategy for fabricating layered nanocomposites using ion diffusion-induced directional gelation. This ultrafast volumetric production, including controllable thickness growth with no size restriction, results from continuous gelation and convenient post-processing, whose fabrication rate is 21.7 times that of ice templating, 13.2 times that of vacuum filtration, and 3.1 times that of electromagnetic induction. Furthermore, layered alumina/epoxy nanocomposites were prepared with superior specific strength (2.9 MPa m1/2/(Kg/m3)) and specific toughness (96.2 MPa/(Kg/m3)), demonstrating the validity of our strategy for layered structures. Moreover, our approach can be extended to other material systems and arbitrary shapes for multifunctional applications in wearable devices, sensors, and anti-corrosion coatings.

A systematic numerical and experimental study into the mechanical properties of five honeycombs

Honeycombs are engineered cellular materials that often show superior specific strength, stiffness and energy absorption compared to solid materials. As a consequence they have found numerous applications across engineering fields. The development of additive manufacturing (AM) technologies has initiated an abundance of studies into novel honeycombs as historic manufacturing constraints are lifted. Investigations have been focused on improving or tailoring a given property but very few have focused on isotropy, and little has been done to bring together different patterns under the same manufacturing and experimental conditions. In this study, AM has been used to manufacture nominally identical honeycombs based on differing unit cells, in a range of orientations and densities. Elastic and plastic properties for the hexagon, triangle, square, re-entrant and double-V honeycombs have been obtained through mechanical testing. The elastic properties of these honeycombs have been modelled for all possible in-plane loading directions using minimal computational resources. The effect of orientation and density has been presented, confirming the level of in-plane isotropy for dense honeycombs with regards to Young’s modulus, Poisson’s ratio, yield strength and compressive strength. Insights have also been gained into how these properties vary with relative density. These results provide a basis for comparison with future work on honeycombs.

Quasi-static compressive performance of 3D printed polymer composite cellular cubic structures-An experimental study

Light weight cellular structures have gained extensive attention in the impact energy absorption applications owing to their superior specific strength and excellent crashworthiness characteristics. The main objective of the present research work is to utilize this benefit to tailor and to improve the structural design and material type of cellular structures for crashworthiness applications. Cubic structures with four different types of design patterns such as concave, convex, hyperbola, and hexagon were proposed and fabricated through three-dimensional (3D) printing technique. Four polymeric filament materials such as Poly lactic acid (PLA), Acrylonitrile butadiene styrene (ABS), PLA mixed carbon fiber (PLA/CF), and Polyethylene terephthalate glycol (PETG), mixed carbon fiber (PETG/CF) were utilized. Accordingly, the compression tests were performed on the fabricated cellular cubic structures under quasi-static loading to examine the effect of design pattern, and material types on the compressive behavior and energy absorbing characteristics. The results revealed that the convex design pattern of 3D printed PETG/CF cubic structure showed the significant energy absorbing characteristics compared to the other three design patterns. It is emphasized that the proposed 3D printed cubic cellular structures have great prospective to substitute the traditional energy absorbing structures in automotive vehicles and high speed trains.