Energy Absorption Performance Research Articles

Crashworthiness Analysis of Bio-Inspired Fractal Plant Stems Multi-Cell Circular Tubes

A novel structure resembling plant stems, termed bio-inspired fractal plant stems multi-cellular circular tubes (BFPMC), was developed by incorporating fractal plant stem characteristics into smaller circular tubes within larger ones. The crashworthiness of this structure under axial impact was investigated using a validated LS-DYNA finite element model. The energy absorption performance of BFPMC tubes, varying in the number of branches, fractal orders, and inner circular diameters, was numerically studied. The numerical findings reveal a 19.27% increase in specific energy absorption (SEA) for BFPMC with [Formula: see text][Formula: see text]mm compared to [Formula: see text][Formula: see text]mm, indicating that filling a single circular tube can enhance the structure’s impact resistance. Subsequently, structural parameters conducive to excellent energy absorption characteristics were determined for various combinations of a number of branches, fractal order, and inner circle diameter parameters. These results offer valuable insights for designing multi-cellular double tubes with high energy absorption efficiency.

Crashworthiness analysis and optimization of brain-coral-inspired multilayer sandwich structures under axial crushing

Inspired by brain corals and cuttlebone, this study employed 3D printing technology to fabricate a novel bio-inspired multilayer sandwich structure based on the Hilbert space-filling curve (named BHSS). The mechanical behavior and deformation process of the BHSS were compared through quasi-static axial crushing experiments and finite element (FE) simulations. The energy absorbing characteristics of the BHSS with different layers were compared through FE simulations, and the results indicated that the 4-layer BHSS displayed superior crashworthiness. Then, parametric studies were conducted to investigate the influence of layer-height gradient and wall-thickness gradient on the energy absorption performance and deformation modes of the BHSS. It was confirmed that the double gradient designs significantly reduced the initial peak force and improved the specific energy absorption of the BHSS. Finally, the multi-objectives optimization based on response surface method and the non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the geometric parameters of the BHSS, aiming at the optimal configuration for better crashworthiness. Compared to the original design structure, the SEA of the optimized knee point structure was increased by 21.8% and the IPF was reduced by 72.6%. These findings provided valuable guidelines for the brain-coral-inspired design of multilayer sandwich structures with superior energy-absorbing performance.

Effects of differential hardening on energy absorption prediction of AA6061-T6 thin-walled rectangular tube

In this study, the energy absorption characteristics and deformation modes of AA6061-T6 thin-walled rectangular tube are investigated experimentally and numerically under different crushing conditions, including axial crushing, three-point bending and oblique crushing. Mechanical tests are carried out on four specimens of uniaxial tension, uniaxial compression, shear and plane strain tension along different loading directions for AA6061-T6. Besides, the effect of differential hardening behavior on the energy absorption prediction of AA6061-T6 rectangular tubes is illustrated by comparing Lou2022, von Mises and SY2009 functions. The mechanical experiment results indicate that AA6061-T6 shows obvious anisotropy, differential hardening behavior and tension-compression asymmetry, and its plastic evolution is accurately characterized by the Lou2022 model. The axial crushing properties show that the AA6061-T6 thin-walled rectangular tube undergoes the progressive symmetrical folding deformation mode. The introduction of geometric discontinuity can obviously reduce the peak force and improve the crashworthiness performances under the axial load. The main crushing mode is bending with a small amount of indentation for three-point bending. Moreover, the three-point bending simulation shows that the Lou2022 function considering differential hardening behavior has the highest simulation accuracy. Three different oblique crushing simulations of 10∘, 20∘ and 30∘ illustrate that the AA6061-T6 rectangular tube at 10∘ mainly occurs progressive folding deformation. while the other two oblique crushing angles undergo global buckling deformation. The total energy absorption at 10∘ is 1.87 and 2.43 times of that at 20∘ and 30∘, respectively. The crushing force efficiency of 20∘ and 30∘ is 41.28 % and 31.8 % lower than that of 10∘, respectively. A comprehensive understanding of the energy absorption performance of AA6061-T6 thin-walled rectangular tube under different crushing conditions is helpful to determine its position and shape as a vehicle safety structure, and to exert its optimal plastic deformation potential to dissipate the collision energy and ensure passenger safety.

Compressive properties and energy absorption of selective laser melting formed Ti-6Al-4V porous radial gradient scaffold

Uniform porous structures are widely considered as the biological implant materials, but they are difficult to meet the needs of complex bone transplantation. The radial gradient porous structure can match the mechanical properties of different levels of natural femur by adjusting the internal and external porosity. Based on Gyroid unit cells, a parameterized model was employed to create a biomimetic bone structure. Uniform porous structure with an average porosity of 50% and radial gradient porous structure were prepared by selective laser melting (SLM).The mechanical properties, deformation behavior and energy absorption properties of uniform and radially graded porous structures were studied by compression test and finite element method (FE).The results show that the compression test curves of all porous structure exhibit elastic stage, platform stage and densification stage. In the platform stage, uniform porous structures are prone to early shear failure and poor energy absorption performance, whereas radially gradient porous structures exhibit higher elastic modulus and yield strength. When the strain is 0.3, uniform porous structures and porous structures with an inner porosity of 80% mainly exhibit 45° flexural-shear failures, while radially gradient porous structures with inner porosity of 62.5% and 70% experience V-shaped shear failures. Porous structures with an inner porosity of 70% have good energy absorption (107.99 MJ/m3), maximum energy absorption efficiency (46.94%), elastic modulus (5.2 GPa), and yield strength (296.02 MPa), matching the demands of cortical bone.

A novel method for optimizing energy absorption of tensegrities with multi- self-stress modes

To explore the factors that affect the energy absorption performance of tensegrities with multi-self-stress modes, the Beetle Antennae Genetic Algorithm (BAGA) is carried out in developing reasonable energy absorption optimization strategies. In the first stage, based on the form-finding theory, the initial self-stress (including prestress level and distribution) that meets unilateral property of components was found. Then, the maximum energy that the structure can absorb under vertical loads is taken as the objective function, and constraint conditions regarding cable relaxation, elastic failure, global volume, strut buckling and component collision are considered in obtaining the satisfactory optimal initial self-stress. Finally, three tensegrities with multi-self-stress modes are taken as illustrative examples, the impact of optimal prestress level and the corresponding distribution on the structural energy absorption performance are explored. The results indicate that, for a 18-rod tensegrity and two types of assembled complicated tensegrity, the energy absorption can be respectively increased by about 156.88 %, 50.75 % and 131.09 % with simultaneously optimizing the pre-stress level and its distribution, verifying the effectiveness of the proposed algorithm. Additionally, for the assembled complicated tensegrity constructed using two different assembling ways (corresponding to different assembled prestress distributions), the optimal structural energy absorption ratio can be as high as 1.88 times.

Biaxial porosity gradient and cell size adjustment improve energy absorption in rigid and flexible 3D-printed reentrant honeycomb auxetic structures

This paper compares different uniaxial and biaxial graded designs of auxetic reentrant honeycomb structures to enhance their mechanical properties, especially the specific energy absorption under compressive load. The lattice structures were 3D printed using the vat photopolymerization masked-stereolithography technique from two different materials – tough (OR) and flexible (FR). The results were evaluated from a material and structural point of view, investigating the effect of porosity, cell number, size, graded design, and fracture mode. The universally best energy-absorbing performance was found in a biaxially graded structure with a center-wise location of the highest local porosity. Depending on the used resin, its energy absorption capacity was up to 2–3 times enhanced compared to a reference uniform-porosity auxetic design. The presented data constitutes a fundamental understanding of auxetic structures and identifies practical approaches for tuning the auxetic structures’ performance regarding their mechanical response. Finally, this study demonstrates the potential of shape versatility offered by 3D printing and other additive manufacturing techniques.

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.

Energy absorption behavior of aramid/DCPD backing to determining the blunt trauma criterion of a human head in a ballistic helmet

The research involved analyzing a material solution for a 9 mm Full Metal Jacket (FMJ) Parabellum loaded with ballistic impact on a resin laminate strengthened with extra aramid layers. The goal of this research is to determine the impact of material (aramid/DCPD) layer thickness on the energy absorption performance of the laminate for blunt trauma as blunt criterion (BC). For this purpose, aramid fiber laminate with dicyclopentadiene (DCPD) resin matrix was prepared. Laminate samples were tested on the drop test and were subjected to ballistic loads. The ABAQUS/Explicit program and finite element method were used to conduct the study. Individual material systems' optimal solutions were created using numerical analysis, and they were then classified using the mass-efficiency criterion. The numerical results were compared with the experimental using samples prepared according to the modeling methods. Selected results were shown and discussed in the later part of the paper.

Crushing Performances of Kenaf Fibre Reinforce Composite Tubes

The quest for sustainable and eco-friendly materials has led to a burgeoning interest in natural fibers as reinforcements in composite materials. Kenaf fiber, derived from the Hibiscus cannabinus plant, presents a promising avenue for enhancing the mechanical and energy absorption properties of composite tubes. This study focuses on the fabrication of composite tubes using a combination of kenaf fiber and epoxy resin. The composite tubes were then subjected to compressive testing to evaluate their energy absorption performances. The fabrication process involved the impregnation of kenaf fibre with epoxy resin, followed by winding and curing to form composite tubes. Different configurations of kenaf fiber content were utilized to investigate their impact on the structural integrity and energy absorption capabilities of the tubes. Compressive testing was conducted to assess the energy absorption behaviour under axial loading conditions. The results revealed that the incorporation of kenaf fiber significantly influenced the energy absorption capabilities of the composite tubes. Higher kenaf fiber content demonstrated improved energy absorption performance, showcasing the potential of kenaf fiber as an efficient energy-absorbing reinforcement. The findings of this study offer valuable insights into the use of sustainable and renewable resources, such as kenaf fiber, in enhancing the mechanical and energy absorption properties of composite structures, thereby contributing to the development of eco-friendly and high-performance materials.

Investigation and optimization of energy absorption performance of axially joined metal and composite foam-filled hybrid tubes

Investigation and optimization of energy absorption performance of axially joined metal and composite foam-filled hybrid tubes

Energy absorption characteristics and multi-objective optimization of 3D bionic negative Poisson’s ratio honeycomb

This paper introduces a new bionic cell element with a negative Poisson’s ratio, which is derived from the traditional re-entrant hexagonal cell element. By incorporating rotation into the two-dimensional (2D) cell element, a three-dimensional (3D) cell element is formed, which exhibits enhanced mechanical properties. The 3D honeycomb is obtained by arraying the 3D cell elements and is enhanced by adding longitudinal ribs to the honeycomb. The present study employs the ABAQUS/EXPLICIT software to investigate the correlation between various compression velocities and the crashworthiness and energy absorption capacity of a given system. The effects of different compression velocities on the 3D honeycomb deformation pattern and energy absorption performance are analyzed. The simulation results show that the new bionic negative Poisson’s ratio honeycomb has better crashworthiness and energy absorption capacity than the traditional re-entrant hexagonal honeycomb. The nominal stress-strain curves of different honeycombs and the energy absorbed per unit mass of honeycomb are compared and analyzed, and the NSGA-II genetic algorithm is used to perform a multi-objective optimization analysis of the peak stress and energy absorbed per unit mass of honeycomb. The results show that the optimized honeycomb can increase the absorbed energy per unit mass by 7.5 % when the peak stress is the same as the initial honeycomb, while the peak stress can be reduced by 9.6 % when the absorbed energy per unit mass is the same.

In-plane crushing behavior and energy absorption of sponge-inspired lattice structures

Novel energy-absorbing structures were a crucial requirement for the structural crashworthiness design in the automotive and aerospace industries. Inspired by the unique double-diagonal reinforced configuration of deep-sea glass sponge, we proposed a bionic lattice structure (BLS) fabricated by additive manufacturing (AM). In-plane quasi-static compression tests and numerical simulations were conducted on BLS with varying wall thicknesses (t), and two distinct deformation modes were observed: layer-by-layer mode with zero Poisson's ratio (ZPR) and uniform deformation mode with negative Poisson's ratio (NPR). The effects of structural parameters on the crushing behavior of BLS were investigated by numerical method. It was found that BLS with wall thickness (t) of 1.2 mm exhibited better energy absorption performance than 0.45 mm, with the energy absorption (EA), specific energy absorption (SEA), and mean crushing force (Pm) increased by 745.0%, 216.5%, and 744.3%, respectively. The change in crushing mode was caused by the ‘+’ shaped joints changing from buckling to rotation, and the crushing behaviors of BLS could be effectively controlled by adjusting unit size and unit number. Finally, theoretical prediction models were developed using simplified super folding element (SSFE) theory to gain deeper insights into crushing behavior and performance of BLS. The present study provided valuable insights into the in-plane crushing and energy absorption capabilities of BLS. Moreover, it highlighted the potential of the double-diagonal reinforcement design in developing innovative energy-absorbing structures.

Impact resistance analysis of a dual-constituent negative Poisson’s ratio lattice metamaterial with tailorable coefficient of thermal expansion

The combination of parameters such as negative Poisson’s ratio (NPR) and negative coefficient of thermal expansion (NCTE) can result in novel materials with specialized functions to meet the requirements of multifunctional and multipurpose devices. However, the additional structural design to meet NCTE requires a re-examination of its impact resistance. In this paper, the deformation modes and impact resistance of dual-constituent re-entrant hexagonal lattice metamaterial (DRHLM) with both NPR and NCTE are investigated under different impact velocities, and the nominal stress–strain curves and energy absorption characteristics of DRHLM structures with different arch heights, chord lengths, and angles of the bottom edge ribs and the diagonal ribs are discussed. The results show that the bi-material bending ribs affect the energy absorption of the structure, and in most cases the DRHLM structure has a better energy absorption capacity than the traditional concave hexagonal structure, but too much or too little curvature of the bi-material portion reduces the energy absorption characteristics of the DRHLM structure. In addition, the increase in the pinch angle of the ribs leads to the weakening of the negative Poisson’s ratio effect, which is also detrimental to the energy absorption of the structure. The work done can provide guidance for finding the dimensional parameters of DRHLM structures with optimal energy absorption performance.

Experimental and simulation study on effects of material and loading direction on the quasi-static compression behavior of re-entrant honeycomb structure

The re-entrant honeycomb structure has a strong energy absorption capacity because of its auxetic characteristics. The energy absorption capacity of the re-entrant honeycomb structure is closely related to the material and loading direction. In this paper, the Selective Laser Sintering(SLS) 3D printing technology was used to print the re-entrant honeycomb structure with commonly used FS3300PA and Glass Fiber reinforced FS3300PA. A quasi-static compression finite element model was developed for the re-entrant honeycomb structure printed with two materials when loaded along three directions. The influence of material and loading direction on the quasi-static compression performance of re-entrant honeycomb structures was systematically studied through simulation and experiments. The deformation mode and energy absorption index of the simulation results are in good agreement with the experimental results, verifying the effectiveness of the finite element model. The results show that the deformation mode and energy absorption performance of the structure are affected by the material and loading direction. The quasi-static compression performance in the Y direction is optimal for both materials. However, when loading along the Y direction, the specific energy absorption of FS3300PA printed re-entrant honeycomb structure is 18.3 % higher than that of FS3300PA + 30 % Glass Fiber printed re-entrant honeycomb structure, ηCFEis 83.3 % higher. Therefore, when the re-entrant honeycomb structure of the two materials is loaded in different directions, the structure printed with FS3300PA has the best quasi-static compression performance when loaded in the Y direction.

Directional damping design of viscoelastic composites via topology optimization

Design of architected functional materials that possess desired damping performance is a topic of great interest in both academic research and industrial applications. This study investigates the concept of ‘directional damping’ for viscoelastic composites and develops a topology optimization framework to achieve directional damping design. Microstructures with both load-bearing capacity and dominant damping in the prescribed direction are obtained by maximizing the loss factor while imposing stiffness constraints. An optimized directional damping microstructure design exhibits a loss factor 1.8 times higher than the isotropic design in the prescribed direction. It is found that the optimized configurations with curved viscoelastic strips are similar to wavy ‘suture’ lines in the beaks of woodpeckers, which possess outstanding energy absorption performance. We have also verified the superiority of the directional damping design through numerical simulations and experiments of the microstructured composites. The experiment results show significant reduction of peak response for the directional damping design compared to the isotropic counterpart. To demonstrate the application potential of the optimized unit cell microstructures, a novel conceptual airless tire that exhibits improved stiffness and shock absorption performance is designed and validated through both numerical simulations and experiments.

Impact resistance of assembled plate-lattice auxetic structures

Auxetic materials are attracting increasing interest due to their extraordinary or even abnormal mechanical properties. Different from the traditional truss-lattice structures, this paper proposes a series of novel auxetic plate-lattice structures with an excellent auxetic effect. Utilizing a dual-materials glue-free assembly design involving hyperelastic and plastic materials, these plate-lattices exhibit numerous advantages such as disassembly, assembly, replacement, recyclability, reusability, excellent energy absorption, high specific stiffness, and impact resistance performances. Quasi-static/dynamic tests and simulations are conducted to assess mechanical properties, including elastic constants, deformation modes, and mechanical responses. Simultaneously, the effect of the principal geometric parameter, concave angle, on the structural response was analyzed with various impact velocities. Findings suggest that the concave angle influences the structural elastic constants under compressive loading. The stress–strain response exhibits a distinct dual-plateau phenomenon. Taking the A65 (concave angle is 65°) configuration as an example, the stress on the second plateau is approximately 2.7 times that of the first plateau, significantly enhancing the structure's energy absorption capability. Under dynamic impact loadings, different configurations and varying impact velocities affect the structure's energy absorption performance. This paper introduces a series of assemblable plate-lattice structures with an auxetic effect, offering design insights and guidance tailored to the convenient transportation, unconventional structures, and rapid assembly needs of lightweight, impact-resistant mechanical metamaterials.

Experimental and numerical study on energy absorption performance of truncated origami materials

In this study, a truncated origami structure, originated from the Miura-ori structure, was designed. The compressive behaviors of this structure subjected to x2-direction (in-plane) and x3-direction (out-of-plane) compression were studied both experimentally and numerically. The structure with a smaller truncated ratio value, e, was more similar to a dense solid. Representative specimens of the Miura-ori and the truncated origami designs were fabricated and tested under both quasi-static and dynamic (v = 7 m/s) conditions. Compared to the Miura-ori structure, the truncated origami showed higher specific energy absorption (SEA) and less load drop between the initial peak force and mean crushing force. In both loading directions, the SEA increased as the truncated ratio decreased for the truncated origami specimens, which was comparable under both quasi-static and dynamic loading. The truncated origami was extrapolated to a numerical model with 5 × 5 × 5 cells to mimic a block of material, and the effects of truncated ratio and loading velocity were investigated. As the e decreased, the deformation mode gradually changed from rigid folding and progressive deformation to plate buckling mode under quasi-static compression. This change was accompanied by an increase in both SEA and overall strength. The truncated origami exhibited the best energy absorption performance when e = 0.4. Under quasi-static compression in the x2- and x3-direction, the SEA of truncated origami is 3.2 and 1.6 times that of Miura-ori metamaterial, respectively. The truncated origami materials with a truncated ratio of 0.8 remained velocity-insensitive up to 25 m/s and displayed similar strength and deformation modes as under quasi-static loading. At a speed of 50 m/s the deformation became more localized, and the SEA increased significantly. The auxetic and expansion behaviors were significantly diminished under higher impact velocities.

Mechanical Behaviors of Hybrid Composites with Orthogonal Spiral Wire Mesh and Polyurethane Elastomer

This work aims to significantly improve the mechanical properties of conventional rigid lattice structures under repeatable large deformations. A novel hybrid material is proposed based on the concept of interpenetrating composite materials. The material utilizes a woven TC4 orthogonal spiral wire mesh as the skeleton and PU elastomer (OSWM‐PU) as the matrix. The uniaxial tensile tests demonstrate that OSWM‐PU possesses the excellent load‐bearing capacity, allowing for large deformations (≥60%) while maintaining partial integrity even after matrix fracture. Optical measurements and simulation analysis reveal that Poisson's ratio can be adjusted within a certain range by manipulating the microscopic parameters (p, d) of the longitudinal helical filaments. Cyclic tensile experiments further demonstrate that OSWM‐PU exhibits exceptional energy absorption performance, multiple energy dissipation modes, and a more pronounced Mullins effect. The stress relaxation experiment reveals the significant influence of the volume fraction of the skeleton on long‐term loading conditions. The orthogonal spiral wire skeleton exhibits a superior hooking effect without dividing the matrix, enabling OSWM‐PU to possess enhanced collaborative deformation capability and inherent designability in the orthogonal direction. These characteristics make it highly promising for applications in various robot joints and as flexible aircraft skin, offering excellent prospects for utilization.

A comparative study on ballistic performance of 3D woven fabrics under different boundary conditions

The potential of 3D woven fabrics as impact resistant material is increasingly recognized. Clarifying their ballistic response under varying boundary conditions is essential prior to deployment. This study aims to investigate the influence of various boundary conditions on the ballistic performance of 3D woven fabrics. Three aramid interlock woven fabrics, each with the same layer count, were designed and fabricated. A verified finite element model of ballistic impact at the yarn level was constructed for a comprehensive analysis. The influence of various boundary conditions on ballistic performance, including ballistic curve, stress distribution, back deformation, and energy absorption, is analyzed. It indicates that boundary conditions significantly affect the impact resistance and response mechanism of the fabrics. Among the different conditions, the fabric under Warp-sides held exhibits greater sensitivity. In the study, the fabric with vertical through-thickness warp yarn structure has smaller out-of-plane displacement, while the fabric with a multi-layer warp yarn structure exhibits better stability in energy absorption performance. The study investigates the response and performance of fabric configurations subject to various boundary conditions, and findings are valuable for the creation of 3D woven fabric designs that leverage boundary effects.

Structural improvement of 3D woven honeycomb composite liner for enhanced energy absorption and impact performance in aircrew helmet

This study aims to enhance the performance of aircrew helmet liners made of 3D woven honeycomb composites through structural improvements. To achieve this, an optimization of the honeycomb design was carried out using a statistical tool by varying its geometrical parameters. A Box Behnken design was employed, using three independent factors: cell height, cell size, and cell wall thickness to assess its impact and their interactions on responses. The performance was evaluated using a multiobjective response to maximize impact energy absorption, achieve the target cushion factor, and balance relative density for lightweight design. Since the liner materials were subjected to flatwise compression and dynamic impact tests to assess the performance. Their behavior. The results revealed that the honeycomb core with a cell height of 15 mm, a cell size of 10 mm, and a cell wall thickness of 0.6 mm exhibited good behavior. The response surface analysis and contour plots were used to analyze the interactions and combined effects of variables on each response. It was observed that lesser cell size shows significant improvement in impact energy with higher wall thickness. However, the cushion factor implies inadequate energy mitigation. The analysis comparing desirability and confirmatory experiments highlighted the potential for the aircrew helmet liner to achieve its maximum performance. This study provides valuable insights into the structural design of 3D woven honeycomb composite liners for aircrew helmets and its findings signify the potential for applications in the aerospace and defense industries.