Energy Absorption Performance Research Articles

Hierarchical multi-cell hexagonal tubes under oblique crushing

Bio-inspired structures have been extensively studied under axial compression; however, limited studies investigating their crushing performance under oblique compression. In this paper, the oblique crushing performance of three types of hierarchical hexagonal tubes, bio-inspired hierarchical multi-cell hexagonal tubes (BHMH), hierarchical multi-cell hexagonal tubes (HMHA and HMHB) have been investigated. The effects of loading angle and hierarchical order are investigated. It has been found that BHMH tubes display the superior energy absorption performance compared with HMHA and HMHB tubes. In addition, BHMH, HMHA and HMHB tubes show the excellent crushing performance than that of single tubes. For example, the SEA of BHMH-3 tube at angles of 0°, 10°, 20° and 30° is 146%, 116%, 75% and 42% higher than that of single ones.

Induced structure and its gradient design on energy absorption properties and failure behavior of aluminum/carbon fiber reinforced polypropylene super hybrid tube

AbstractThe metal/fiber super hybrid tube is a mixture of pure metal and carbon fiber structure, featuring both stable energy dissipation of the metal and good energy absorption efficiency of the composite, with greatly improved lightweight. However, the failure mode of the hybrid tube is unstable and prone to Eulerian buckling, which affects its energy absorption performance. In this work, aluminum alloy/carbon fiber reinforced polypropylene super hybrid tube (Al/CFPP super hybrid tube) have been obtained through the addition of an induced structures, which aims at reducing the maximum peak load generated during collision. The effects of induced grooves and holes structure (number of holes, diameter and row number) on the damage and energy absorption were discussed. The results showed that the initial peak load can be effectively reduced by adding an induction groove structure. When the number of induction holes is 4, the diameter is 5 mm, and the number of rows is 1, the initial peak load decreases by 14.06%, and the total energy absorption is basically unchanged. Additionally, the gradient design of the hole diameter and spacing significantly helped guide the gradual failure of the structure, with the initial peak load decreased by 21.98% and the total absorption energy increased by 20.26%.Highlights Super hybrid structures were developed to improve crashworthiness. The effect of induced grooves energy absorption was analyzed. The effect of hole size and quantity energy absorption were analyzed. A gradient design of hole size and spacing was proposed. The combined of the induction hole and trigger angle was demonstrated.

Numerical investigation on energy absorption characteristics and damage modes of biomimetic thin-walled structures in aircraft

The crashworthiness of aircraft is essential for both airlines and passengers. Creating lightweight protective structures that achieve a balance between weight and impact resistance while also providing excellent cushioning and energy absorption presents a significant challenge for aircraft designers. The desert beetle's exoskeleton demonstrates remarkable strength and toughness, effectively shielding its body from external threats. This study examines the desert beetle's exoskeleton by developing bio-inspired thin-walled models with three distinct bottom structures based on its cross-section. Numerical simulations were used for calculations and model optimization. The research systematically investigates how various design parameters, such as impact angle, number of support plates, and wall thickness, affect energy absorption performance. The findings indicate that increasing the inclination angle notably decreases the energy absorption capacity of the protective structure, while adding more partitions can significantly enhance this capacity. Additionally, changes in wall thickness directly influence the structure's compressive performance. Furthermore, a comparative analysis of the optimized structure's energy absorption characteristics under various conditions is provided. Ultimately, this paper highlights the significance of design optimization for protective structures in micro aerial vehicles and outlines future research directions to better balance performance and practicality.

Design of non-homogeneous three-dimensional ceramic lattice structures with interpenetrating epoxy resin for enhanced energy absorption and load-bearing performance

Lightweight, energy-absorbing materials with superior mechanical properties are vital for engineering. Interpenetrating phase composites (IPCs) of Al2O3 ceramic and epoxy resin exhibit enhanced performance via non-homogeneous lattice design. Compression tests showed over 60% strength improvement compared to single-phase materials, while bending tests highlighted greater load capacity. Non-homogeneous structures demonstrated superior energy absorption and load-bearing abilities. Epoxy resin enhanced toughness under compression but not bending. A bulletproof model validated the practical potential of IPCs, emphasizing their engineering applicability in optimizing material properties through tailored lattice designs.

Investigation of the flow characteristics of slit check dams using novel models

Floods, which cause loss of life and property and destruction of the environment, have devastating effects on socio-economic welfare. Slit-check dams are essential structures for managing the transport of silt and woody debris, especially in events of significant floods. The current study presents the hydraulic characteristics of slit-check dams with different geometries for experimental and numerical tests. First, the Butterfly model was produced with a 3D printer and examined experimentally. Then, the Butterfly model was validated extensively using OpenFOAM (v7) software for the numerical analysis. Finally, the other models were examined numerically using the k-ε turbulence model. The changes in water surface profile, velocity profiles, energy dissipation rates, and streamlines were comprehensively examined and discussed. The results showed that slit-check dams caused hydraulic jumps and dissipated flow energy. The Arced and Rectangular models, in particular, demonstrated a significant performance for energy dissipation, which is essential for flood management. Water surface profiles are directly affected by discharge. Moreover, the cross-sectional length of the model in question significantly affects the water surface profile. Accordingly, an increase was observed in the velocity profiles along the slit-check dam. While the maximum velocity for all unit discharge was observed in the V-shaped model, the minimum velocities were observed for the Arced and Rectangular models. Thus, the energy absorption performance of Arced and Rectangular models is higher.

Crushing and energy absorption behavior of self-similar nested hierarchically hexagonal honeycomb

To enhance the impact resistance of honeycomb structures, this article proposes a novel self-similar nested honeycomb structure (SNHRH) by incorporating self-similar ribs within the honeycomb framework. Finite element simulations and experimental validations were conducted using Abaqus software. The results from the out-of-plane crushing tests demonstrate that the SNHRH exhibits superior energy absorption capabilities compared to conventional honeycomb structures, hierarchical multifunctional chiral metamaterials, and spider-web hierarchical honeycombs. Furthermore, the enhanced energy absorption characteristics of the SNHRH-1 are not merely attributable to the incorporation of internal cytokinetic elements; rather, they arise from the interactions among these internal components, which result in more pronounced plastic deformation at the intersections. To further elucidate the impact of geometric parameters on the crashworthiness of the proposed honeycomb structure, this study analyzes the significant effects of relative density, rib angle, and thickness ratio distribution. The accuracy of the finite element simulation results was verified through compression tests. The findings indicate that relative density is positively correlated with energy absorption, specific energy absorption, initial peak crash force, and crushing force efficiency. An increase in relative density corresponds to higher energy absorption and specific energy absorption while maintaining constant wall thickness. Notably, within the same type of honeycomb structure, higher orders exhibit improved energy absorption performance. Specifically, the energy absorption of SNHRH-4 was found to be 88.63% greater than that of SNHRH-1.

Crashworthiness Analysis of a Novel Double‐Filled Hierarchical Hexagonal Tube Subjected to Axial Impact

This article presents a novel double‐filled hierarchical hexagonal (DHH) tube. An Abaqus finite element model is utilized to investigate the crashworthiness of this structure under axial impact. A numerical analysis explores the energy absorption (EA) performance across varying different inner hexagon side lengths, fractal orders, and tube masses. The results indicate that specific EA (SEA) increases with the hierarchical order, with the SEA of the second‐order DHH tubes being 9.22–24.70% higher than that of conventional single‐layered hexagonal tubes and 39.20–43.30% greater than that of conventional single‐filled hierarchical tubes. The DHH structure demonstrates optimal performance with an inner hexagon side lengths of 15 mm, achieving the highest SEA across different parameters. This study provides valuable insights for designing hierarchical multicell double tubes with improved EA efficiency.

Bionic Inner-Tapered Energy Absorption Tube Featuring Progressively Enhanced Fold Deformation Mode

Slender tubes are in high demand owing to their lightweight and outstanding energy absorption. However, conventional slender tubes are prone to catastrophic failures such as Euler’s buckling under axial load. Interestingly, growing bamboos overcome this similar dilemma via a unique tapered intine in the internodes, which endows them with excellent energy absorption. Inspired by this finding, a bionic inner-tapered tube (BITT) was designed to enhance the energy absorption of slender tubes under axial load. The special energy absorption (SEA) was evaluated via a quasi-static axial compression test. Then, theoretical calculation and finite element analysis were carried out to analyze the energy absorption mechanisms. The results reveal that the tapered inner wall induces a progressively enhanced fold deformation mode for BITT, which not only prevents buckling failure and decreases initial peak crushing load but also improves the energy absorption efficiency by increasing plastic deformation. The influences of taper and length–diameter ratio on the axial energy absorption of BITT are explored. Finally, the bionic square array (BSA) and bionic hexagon array (BHA) are fabricated by taking BITT as the basic structural unit, which significantly improves the main energy absorption performance indicators under axial load.

Study on the mechanical properties of the thin-walled double circular tube filled with a novel NPR lattice core based on the concave rotating mechanism

Abstract This study presents a thin-walled double circular tube filled with a novel negative Poisson’s ratio(NPR) lattice core based on the concave rotating mechanism. The unit cell of the NPR lattice core is constructed by replacing each inclined side of a concave hexagon with a smaller concave hexagon with an identical geometry aspect ratio. The single cell is arrayed to obtain a two-dimensional honeycomb structure, and then curling and mirroring operations are utilized to get a circular tube structure. Compressive deformation and load-displacement response of NPR lattice core with different concave angles are analyzed by FEM. To validate with numerical results, the NPR lattice core samples are prepared using 3D printing technology and subjected to quasi-static uniaxial compression experiments. Then, the thin-walled double circular tube filled with the NPR lattice core(FDCT) is established. The load-displacement relationship and energy absorption characteristics are analyzed, and the effects of two angle parameters on the specific energy absorption of the structure are discussed. The results show that an increase in the concave angle decreases the rigidity of the NPR lattice core. When subject to compression, all models show NPR effects, with minimum and maximum Poisson's ratios of -0.29 and -0.5, respectively. For FDCT, it is found that the interaction between the core layer and the tube wall enhances the structure's energy absorption performance. Changes in the core layer angle parameters affect the energy absorption of the FDCT structure, where increasing the concave angle improves the energy absorption efficiency of the structure. In contrast, the effect of the rotational angle is not significant.

Tunable mechanical performance of nanoporous energy absorption composite material

Abstract Nanofluidic energy absorption materials (NEAs) represent smart and efficient energy absorption composite materials in the ever-growing application of advanced protective structures. In this paper, an integrated experimental and molecular dynamics simulation study is conducted on the NEAs (ZSM-5/water) to investigate the tunable strategy of mechanical performance and energy absorption by considering the microstructural, mechanical, and thermal factors. The results demonstrate that the NEAs is an efficient and tunable liquid spring-like volume memory material. The typical NEAs show superior energy absorption capacity, achieving a specific energy absorption of 5.17 J/cm³ and an energy absorption ratio of 1.14 J/cm³ per cycle. Compared with insensitivity of the loading rate, the solid-fluid mass ratio is confirmed to significantly affect energy absorption performance, with an optimal ratio of approximate 1. Temperature is validated as an effective in-situ tunable parameter for NEAs in terms of both infiltration and energy absorption properties, with only slight effect on exfiltration. The critical infiltration pressure and specific energy absorption decrease by 23% and 40% as temperature increase from 25°C to 80°C. The gas-fluid interaction based energy absorption mechanism under high temperatures is proposed according to the comparison between experimental results and molecular dynamics simulations. The findings in this work will provide novel materials solutions for the intelligent energy absorption protective structures.

Inhibition of interlaminar damage in CFRP laminates by inserting non-woven carbon fiber interlaminar reinforced tissue

Carbon fiber-reinforced plastics (CFRPs) are known for their high strength and stiffness, essential in high-performance applications. However, in complex structures with fiber discontinuities, such as tapered sections and bolt holes, CFRP laminates are prone to interlaminar damage due to low interlaminar toughness. This study aimed to enhance CFRP interlaminar fracture toughness by inserting non-woven carbon-fiber-reinforced layers. Two non-woven tissues were used: resin-impregnated conventional carbon fiber and resin-free recycled carbon fiber. Evaluations of modes I and II interlaminar fracture toughness revealed that laminates with non-woven inserts had fracture toughness values two to three times higher than pristine CFRP. Non-woven tissues of varying lengths were embedded at ply discontinuities, and tensile tests were conducted to assess their effectiveness. Results confirmed that both non-woven tissues significantly improved interlaminar toughness and effectively suppressed delamination, attributed to high fiber content and complex crack paths, enhancing energy absorption and mechanical performance in CFRP laminates.

Design and characteristics of a double-layer gradient grid structure for broadband electromagnetic wave absorption

Grid structures are renowned for their lightweight and high-strength properties. When combined with wave absorption technology, they can form multifunctional broadband wave-absorbing structures. However, traditional grid wave-absorbing structures face challenges in impedance matching control, limiting their effectiveness over a broader frequency band. Additionally, conventional simulation optimization methods in the field of wave-absorbing structures are inefficient and yield suboptimal results. To address these issues, this study introduces a double-layer gradient grid absorber composite structure (DGGS) and employs a genetic algorithm optimization framework to adjust its structural parameters. By applying the principles of impedance matching and genetic optimization algorithms, the DGGS successfully reduces electromagnetic wave reflectivity, achieving significant absorption effects within the 2.45 to 18 GHz frequency range. Furthermore, the absorber is constructed from composite materials such as fiberglass, ensuring reliable strength and significant cost-effectiveness. The genetic algorithm has optimized the structural parameters to achieve the optimal impedance gradient and maximize absorption efficiency. This structure not only exhibits exceptional mechanical strength but also demonstrates excellent energy absorption performance, presenting broad application prospects.

Experimental investigation on the crashworthy performance of polyurethane foam-filled aluminum cans under repeated impact loads

Sustainable development is a development approach that focuses on economic growth and environmental protection. Substantial natural resources are consumed during the production of aluminum cans. However, recycled aluminum saves 95% of the energy needed to make new aluminum. Additionally, thin-walled tubular structures are widely used as energy absorbers. The current study developed a polyurethane foam-filled aluminum cans (PFACs) composite structure, which could be made of recycled aluminum and adopted as an energy absorber. Quasi-static test and repeated drop weight test were conducted to investigate the crushing performance and the mechanism under multiple impacts of this polyurethane foam (PU foam)-filled composite structure. A novel method which could be used to reasonably quantify their energy absorption performance was proposed to identify the densification displacement of PFACs. Quasi-static test results showed the significant effect of the PU foam filler in improving the energy absorption performance of PFACs comparing to the empty aluminum cans (EACs). Moreover, the composite effect between the aluminum can and the PU foam had a positive effect on the crashworthiness of PFACs. The repeated dynamic impact test results indicated that, compared to EACs, PFACs could withstand repeated impact loads with more repeated numbers and higher impact energy levels. These findings demonstrated PFAC is a promising energy absorber which can be used to withstand repeated impact loads.

The mechanical behavior and deformation mode of multilayer composite structures based on triply periodic minimal surface elements

In this paper, the mechanical behavior and compression deformation mode of three types of composite multilayer structures based on triply periodic minimal surfaces (TPMS) were conducted through experiments and finite element analysis. The results indicate that the load-displacement curves under varying stain rates manifest a double-platform characteristic for all three structure types. The P-G four-layer structure and P-G six-layer structure have no discernible extrusion of the structural layers during compression, and the entirety of the structure displays an almost regular cubic configuration after compression. Nevertheless, local separation was observed in the extruded portion of the P-H six-layer structure after the structural deformation at higher strain rates. For the other conditions, the structure exhibited a bulge but did not display any local detachment or separation phenomena. During the deformation of the P-H six-layer structure, a dome-shaped region emerges in the first and fifth layers. The “crown” layer displays an inverted bell-shaped failure mode for the first layer structure, exhibiting downward extrusion. In contrast, the fifth layer structure displays an upward extrusion and exhibits a bell-shaped failure mode. The P-H 6-layer structure has the best energy absorption performance under quasistatic compression conditions for the P-G 4-layer, P-G 6-layer and P-H 6-layer structure. However, the energy absorption performance of the identical structure remains largely consistent across varying strain rate conditions.

Effects of undulating printing paths on axial compressive behaviors of 3D-printed continuous fiber-reinforced multi-cell thin-walled structure

Thin-walled structures are widely used in passive safety systems of the vehicles because of their excellent lightweight and stable progressive deformation behavior. Recently, continuous fiber 3D printing technique has been successfully applied in the manufacturing of thin-walled structures, providing a promising path to meet increasing requirements for energy absorbers as vehicle speed increases. This paper proposed a range of novel undulating printing paths to fabricate two kinds of continuous Kevlar fiber reinforced multi-cell thin-walled structures (CFMSs) with different cross-section shapes, named MT1 and MT2, respectively. For each type of CFMS, three different printing paths (moving back and forth between two layers) were designed to manufacture CFMS with the wall thickness comprised of only a single deposited line. The axial compressive tests were conducted to investigate the compressive response of CFMSs. It was found that undulating printing paths affect both the mechanical behavior and collapse mode of CFMSs. During the compression process, MT1 and MT2 printed with path 3 showed progressively folding deformation modes (differed from the progressive crushing mode of composite laminated thin-walled structures). Thus, compared to MT2 printed with path 1 and path 2, which exhibit global buckling, MT1 and MT2 printed with path 3 exhibited more stable energy absorption performance. Besides, although the local failure mode in different CFMSs caused by the same path was similar, the same printing path had different influences on the axial compressive properties of different CFMSs.

Effect of hollow beads content in aluminum oxide hollow beads reinforced epoxy composites on mechanical and energy absorption properties of the composites

AbstractAluminum oxide hollow microbeads/epoxy resin composite is a kind of epoxy resin‐based multi‐porous energy‐absorbing material. This study improved the brittleness and toughness of epoxy resin. Adding hollow aluminum oxide microbeads with different mass fractions increased the energy absorption capacity. Quasi‐static compression tests were carried out at room temperature to test the compression properties of epoxy resin/hollow microbead composites. The composites′ energy absorption properties and energy absorption efficiency were analyzed and calculated using the obtained compression curves. The fracture characteristics and microscopic morphology of the composite specimens were observed by scanning electron microscopy. It was found that aluminum oxide hollow microbeads, as reinforcement material, can effectively improve the brittleness and yield strength of epoxy resin materials and enhance the energy absorption performance and energy absorption efficiency of composite materials. With the increase in the mass fraction of hollow microbeads, the energy absorption performance of the composite material first increases and then decreases. Its performance is the most significant when the mass fraction of aluminum oxide hollow microbeads is 10 %.

Graphene origami with enhanced impact resistance and energy absorption performance

The ancient art of origami has recently shown its potential in engineering intricate three-dimensional graphene structures with unique properties. This study employs molecular dynamics simulations to investigate the dynamic mechanical behavior of graphene origami structures (GOS) under hypervelocity ballistic impact. The analysis of residual velocity, kinetic energy loss, and specific penetration energy shows that GOS exhibit superior impact resistance and energy absorption performance compared with pristine graphene. One reason for the enhancements is that highly flexible GOS can unfold to produce a conical impact zone with larger out-of-plane deformation. Another reason is that three-dimensional folded regions possess more mass, enabling them to dissipate more kinetic energy from the projectile. The impact behavior of GOS is further analyzed concerning projectile size, impact position, and surface roughness. It is found that the impact resistance and energy absorption capacity of GOS can be adjusted by altering the surface roughness, specifically the folding degree and pattern geometry. This GOS holds promise for diverse applications in impact protection, such as combat armor and spacecraft shields.

Crashworthiness of an improved cake-cutting multi-cell tube under three-point bending

Abstract Increasing the number of corners has shown great potential for improving the energy absorption of thin-walled pipes. In order to further improve the bending strength and energy absorption performance of the thin-walled tubes, an improved multi-cell thin-walled tube is proposed by adding three rib plates to a straight thin-walled tube structure. A three-point bending numerical model is established to clarify the bending mechanical properties of the proposed cake-cutting multi-cell tube. The results show that at the maximum number of cakes, the deformation is more stable and the specific energy absorption is 3.5 times higher than that of a traditional circular thin-walled pipe. When the loading angle is 60°, the specific absorption energy reaches the best, which is 1.1 times that when the loading angle is 30°. When the loading angle is 60°, the peak impact force is maximum when the distance between the rib position and the center of the circle is 12mm. At other loading angles, the maximum peak impact force is achieved at a distance of 8 mm. This work indicated the effectiveness of the cake-cutting method in improving the bending strength of the thin-walled tube, which deserves more attention in future work.

Compressive response and failure mode of glass fiber reinforced polyimide composite honeycomb with cell wall defects

Obtaining some functions for honeycombs can be normally realized by perforating holes on the cell walls. However, excessive perforations, which are always identified as defects, have been shown to reduce the mechanical properties of the honeycomb. Continuous glass fiber reinforced polyimide composite(GF/PI) honeycombs are prepared in this work to investigate their compression processes by finite element analysis and 3D-DIC assisted quasi-static compression tests in order to further reveal the influence mechanism of perforation-induced cell wall defects on their out-of-plane compressive responses and failure modes. The results show that the failure mode of defect-free GF/PI honeycomb is progressive crushing mode, while the GF/PI honeycombs with certain configurations of cell wall defects fail in a fracture mode and fracture/progressive crushing mixed mode. These failure modes ultimately lead to the degradation of the energy absorption performance of the GF/PI honeycombs with cell wall defects. Subsequently, by increasing the matrix content, the failure modes of GF/PI honeycombs with cell wall defects are altered to progressive crushing owing to the reduction of the average maximum damage strain of the cell wall. In addition, the energy absorption performance of GF/PI honeycomb with the same defects configuration is effectively enhanced by 14.24%. This method significantly improves the compressive response and provides theoretical guidance for the structural-functional integrated design of honeycomb sandwich structures in high-performance radomes.

Numerical Simulation Analysis on Anti-Penetration Characteristics of Al/UHMWPE Composite Plates Against Tungsten Alloy Fragment

Abstract With the rapid growing demand for armor protection systems that prioritize reduced weight, Al/UHMWPE composite plates have become a promising option in armor protection field. In this work, the finite element model of the Al/UHMWPE composite plates against tungsten alloy fragment was established firstly to investigate the influence of the interfacial strength on the ballistic performance. In addition, both the failure mechanisms and energy-absorbing performance of AI/UHMWPE composite plates were also systematically explored. Numerical simulation results indicate that lower interfacial strength can more accurately simulate the phenomenon of sub-laminates separation under high-speed penetration conditions. The failure mechanisms of Al/UHMWPE composite plates involve sequential processes including deformation of the Al alloy plate, tensile deformation of the UHMWPE laminated plate, fracture of the sub-laminate, and finally, delamination of the UHMWPE laminated plate. Furthermore, the specific energy absorption (SEA) was utilized to quantify the ballistic performance between Al alloy plate and UHMWPE plate, demonstrating that UHMWPE plate significantly dominates, with a capability of 16.4 J/(kg/m2), accounting for 53.4% of total SEA.