Crush Force Efficiency Research Articles

The design of circular tubes with stepped varying thicknesses and their synergistic multi-tube combination

A stepped wall circular tube with varying thickness (STVT) and its multi-tube synergistic combination energy absorption structure were developed to address the shortcomings of the high initial peak force of thin-walled metal tubes and the significant load fluctuation of conventional multi-tube combination structures. The STVT was designed with different thickness variations, and its crashworthiness was evaluated numerically and experimentally. An analysis was done on the influences of various characteristics, such as the number of steps and thickness variation, on the crashworthiness of STVTs. Research shows that the STVT with three and four steps has improved crashworthiness. The phase of the curve is significantly influenced by the initial thickness, and for each 0.6 mm difference in step thickness, the peak phase shifts by about 5.5%. In comparison to the combination of four equal-thickness tubes of the same mass, the optimal combination structure optimizes smoothness by 10.67%, energy absorption by 19.52%, crushing force efficiency by 15.30%, and initial crushing force by 20.70%.

Research on In-Plane Deformation Performance of Rotating Honeycomb Structures.

Most natural materials have rotational and hierarchical properties, so they can show excellent mechanical properties such as shear resistance and impact resistance. In order to further improve the energy absorption characteristics of vibration absorbing structures, a new type of honeycomb structure with integral rotation and group rotation is designed and characterized. The effects of the geometrical parameters of rotation Angle on the impact deformation mode, stress response curve and energy absorption characteristics of the honeycomb structure are studied through numerical simulation and experimental design. The results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is the results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is increased by 6%, the bearing capacity is increased by 320 N, and the crushing force efficiency is increased by 2%. Compared with the whole cell and the group cell, the specific absorption energy increased by 35%, 73% and 71%. The results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the optimization of crashworthiness structural design.

Breaking the Tradeoffs between Different Mechanical Properties in Bioinspired Hierarchical Lattice Metamaterials

AbstractIt is a long‐standing challenge to break the tradeoffs between different mechanical property indicators such as the strength versus toughness in the design of lightweight lattice materials. To tackle this challenge, a hierarchical lattice metamaterial with modified face‐centered cubic (FCC) cell configuration, inspired by the glass sponge skeletal system, is proposed. The proposed lattice metamaterial simultaneously possesses high strength, high energy absorption, considerable toughness, as well as controllable deformation patterns through integration of both bionic features of double diagonal reinforcement and hierarchical circular modification. The compressive strength and energy absorption can reach 69.13 MPa and 53.39 J cm3, respectively. Furthermore, the proposed lattice also exhibits exceptionally high damage tolerance compared with existing lattice metamaterials with comparable strength by attenuating stress and deformation concentration that may cause catastrophic collapse. This design approach combines the advantages of tensile‐dominated and bending‐dominated lattices. Quantitatively, in terms of specific strength, specific energy absorption, and crushing force efficiency, the modified hierarchical circular FCC (MHCFCC) lattice metamaterial outperforms the Octet lattice by 14.85%, 53.28%, and 110.52%, respectively. This multibionic feature integration approach provides advanced design strategies for high‐performance architected metamaterials with promising application potential.

Multi-Objective Optimization of Square Corrugation Multilayer Nested Structures

Thin-walled structures, when used for high-speed railways, can effectively mitigate the irreversible destruction when a malfunction occurs. Nested thin-walled tubes, as energy-absorbing structures, possess excellent specific energy absorption (SEA) and crushing force efficiency (CFE). This paper conducts multi-objective optimization by focusing on a square corrugation nested structure with a double octagon inner wall, namely SCOD, to ameliorate the crashworthiness of the nested structure. The finite element model of the SCOD is constructed and validated by test data. A set of experimental design points with good spatial distribution are obtained using the optimal Latin hypercube (LHC) method. The polynomial response surface (PRS) method was applied to establish the fitting relationship between design variables and optimization objectives, and validation is accomplished. The DCNSGA-III algorithm is employed for optimization, resulting in a Pareto alternative solution set with good population diversity and convergence. In addition, to observe the optimized performance, a set of optimal solutions considering a single objective value is derived, and a comprehensive optimal solution is obtained by applying the minimum distance selection method (TMDSM). Finally, the proposed optimized system is analyzed and validated. According to the alternative reference solutions, the initial peak force (IPCF) reduces by 53.75% and CFE increases by 8.7%. This paper provides some reference for the optimization design in practical engineering.

A Footpad Structure with Reusable Energy Absorption Capability for Deep Space Exploration Lander: Design and Analysis

The footpad structure of a deep space exploration lander is a critical system that makes the initial contact with the ground, and thereby plays a crucial role in determining the stability and energy absorption characteristics during the impact process. The conventional footpad is typically designed with an aluminum honeycomb structure that dissipates energy through plastic deformation. Nevertheless, its effectiveness in providing cushioning and energy absorption becomes significantly compromised when the structure is crushed, rendering it unusable for reusable landers in the future. This study presents a methodology for designing and evaluating structural energy absorption systems incorporating recoverable strain constraints of shape memory alloys (SMA). The topological configuration of the energy absorbing structure is derived using an equivalent static load method (ESL), and three lightweight footpad designs featuring honeycomb-like Ni-Ti shape memory alloys structures and having variable stiffness skins are proposed. To verify the accuracy of the numerical modelling, a honeycomb-like structure subjected to compression load is modeled and then compared with experimental results. Moreover, the influence of the configurations and thickness distribution of the proposed structures on their energy absorption performance is comprehensively evaluated using finite element simulations. The results demonstrate that the proposed design approach effectively regulates the strain threshold to maintain the SMA within the constraint of maximum recoverable strain, resulting in a structural energy absorption capacity of 362 J/kg with a crushing force efficiency greater than 63%.

Quasi‐static axial crushing of multi‐tubular foam‐filled carbon fiber reinforced composite structures

AbstractIn automotive design, a key aspect in limiting injuries in the event of collision is the ability of vehicle's structures to absorb high quantities of energy. Recently, automobiles have been designed with materials such as carbon fiber‐reinforced polymers to replace the conventional metallic materials, to boost structural safety and fuel efficiency. In this study, various combinations of carbon fiber‐reinforced plastic and Kevlar‐reinforced polymer composite tubes were assembled to form multi‐tubular composites and their crushing properties were investigated under quasi‐static axial compression. A total of five different combinations were designed and tested. The results showed that the addition of intermediate tubing system in the hollow composite tubes significantly improved the load‐bearing and energy absorption capabilities of the composite tubes. In addition, these configurations were also filled with polyurethane (PU) foam. It was shown that, apart from specific energy absorption (SEA), all the other parameters, such as peak load, mean load, crushing force efficiency, and overall energy absorption ability, were enhanced with the addition of foam. The SEA parameter showed inconsistent behavior, and this was attributed to the weight addition caused by the addition of foam in the composite tubes.Highlights This study examined the crashworthiness properties of multi‐tubular structures. Placing of intermediate tubing showed great improvement in absorption capacity. The system with carbon‐based intermediate tubes performed the best. Filling PU foam within the structures also improved the load‐bearing properties. The SEA was seen to reduce with the addition of PU foam.

Dimensional effect and mechanical performance of node-strengthened hybrid lattice structure fabricated by laser powder bed fusion

ABSTRACT Node-strengthened hybrid structures with lower relative density inspired by solid solution strengthening mechanism, namely the edge center interstitial lattice (ECIL) structures and vertex node substitutional lattice (VNSL) structures were designed and fabricated by laser powder bed fusion (LPBF). The geometric feature-dependent defects distribution, the intense microstructure sensitivity as well as the node size effect on the mechanical response were investigated. The microstructure sensitivity induced by geometric feature was found to be related to the different supporting condition and distinctive thermal history. ECIL-1.5 structure possessed the highest plateau stress of 1.79 MPa and the largest crush force efficiency of 59.1%, which increased by 59.8% and 15.2% compared to the initial face centre cubic with z-struts (FCCZ)structure. VNSL-1.5 exhibited the greatest specific energy absorption of 14.6 J/g, demonstrating the highest strengthening efficiency was achieved at the critical sphere diameter to strut thickness (Sph-strut) ratio of 3. This method further improved lightweight efficiency, indicating the inherent strengthening mechanism of crystal materials could guide the design of metamaterials.

Energy absorption of variable stiffness composite thin-walled tubes on axial impacting

In order to realize the engineering application of automated fiber placement for composite laminates, a method of the variable angle fiber placement was proposed to design the tube structures of variable stiffness composites based on the quadratic Bezier curve. The axial crushing responses were simulated to investigate the energy absorption characteristics of composite tubes. The results showed that the method of the variable angle fiber placement contributed to the improvement of the energy absorption effects. The maximum crushing force efficiency of the variable stiffness composite thin-walled tubes designed by the method was 49.04% which was 106.48% higher than the constant stiffness composite tube. The results could be helpful for the process of automated fiber placement and the design of the energy absorption for composite thin-walled structures.

Crushing behavior of CFRP/AL hybrid tubes under oblique lateral loading

AbstractThis work aims to research the oblique lateral crushing behavior of CFRP/AL hybrid tubes under different parameter configurations. First, a finite element model was established based on the maximum stress criterion and the traction‐separation law. The reliability of the numerical models for pure aluminum, pure composite, and hybrid tubes was verified by rigorous comparison with experimental data, respectively. Second, the influence of loading conditions and geometric characteristics on crashworthiness were studied. The results show that the damage modes of the hybrid tube under oblique lateral loading are mainly concentrated in the horizontal and vertical ends, specifically in the form of plastic hinge and fiber, matrix fracture. The CFRP layers has positive effect on improving the specific energy absorption (SEA). High ratio thickness of aluminum tubes can effectively improve the energy absorption (EA) and crush force efficiency (CFE). It is found that the sandwich structure is not conducive to resist lateral crushing, while the CFRP without external constraints can absorb more impact energy.Highlights The oblique lateral crushing behavior of CFRP/AL hybrid tube was studied. A numerical simulation method was proposed and verified. The effects of loading angle, fiber layers and AL thickness were studied. The hybrid ratio and hybrid method were designed and discussed.

Investigation of the effect of friction force on the energy absorption characteristics of thin-walled structures loaded with axial impact force

In recent years, there has been a significant increase in studies aimed at enhancing the energy absorption capabilities of thin-walled structures used in vehicles. These studies aim to mitigate the adverse effects of shock waves released during crashes by incorporating recesses that trigger folding on the walls of crash boxes, thereby increasing energy absorption. This particular study investigates the energy absorption and crushing behaviors of interpenetrating thin-walled structures under axial crushing conditions. Two different configurations were modeled to determine the contribution of friction force in dampening impacts in thin-walled structures. One configuration exhibited classical folding, while the other initiated folding after interpenetration upon the application of an axial impact load. The interpenetrating structures generate friction forces through recesses and protrusions on the surface of the crash box to provide energy absorption. The simulations were conducted using the finite element method (FEM) in a non-linear explicit dynamic collision scenario. The crash scenarios for both configurations were analyzed under identical conditions using two different materials (DP-600 and DP-800) and three different thicknesses (1.2 mm, 1.4 mm, and 1.5 mm). The dynamic crash simulations were compared based on Specific Energy Absorption (SEA), Total Energy (ET), Peak Crush Force (PK), Crush Force Efficiency (CE), and Mean Crushing Force (FM) values to examine the effects of friction force on energy absorption capabilities and crushing behaviors of the crash boxes. The analysis results demonstrated that friction force and energy absorption play a positive role in the crashworthiness characteristics of thin-walled structures.

Energy absorption characteristics of a super hexagonal honeycomb under out-of-plane crushing

Designing innovative honeycomb materials with improved energy absorption capacity is a long-term pursuit to provide adequate impact protection for crucial structural components. The edge-based design has been regarded as an effective strategy to enhance the mechanical properties and energy absorption of honeycomb materials. This paper proposes a novel super hexagonal honeycomb (SHH) structure to pursue better energy absorption capacities. Its geometry is derived from the outline of a hexagonal honeycomb. The crushing performance of the SHH is investigated based on the out-of-plane compression experiments, and an explicit finite element model is established to explore the crashworthiness characteristics of the structure. Furthermore, a theoretical model based on the simplified super folding element (SSFE) method is established to predict the mean crushing force during the crushing process. The comparison with the experimental and numerical results verifies its accuracy. Besides, the crushing mechanisms and collapse modes of the constitutive Y and V elements in the SHH are discussed. The parametric analysis of the crashworthiness of the SHH is conducted in terms of the cell-wall length ratio, sub-corner angle and hierarchy. The results reveal that the crashworthiness of SHH is much superior to traditional hexagonal honeycomb and presents 106%, 62%, 104% and 162% improvement in the mean crushing force, crushing force efficiency, specific energy absorption and volumetric energy absorption, respectively. This work can inspire future research on lightweight edge-based honeycombs with excellent energy absorption capacity.

Mechanical behavior and crashworthiness assessment of corrugated inner rib reinforced tubular structures

Herein, a novel corrugated inner rib reinforced tubular structures and a gradient design method are proposed. The mechanical response, interaction effect and gradient effect of the proposed tubular structures are systematically studied by means of experiment and numerical simulation. It is found that the corrugated inner rib reinforced tubular structures exhibit a progressive and stable deformation process under axial compression. Compared with the traditional straight inner rib reinforced tubular structures, the initial peak crush force (IPCF) of the corrugated inner rib reinforced tubular structure has a maximum decrease of 26.07%, and the mean crush force (MCF), crush force efficiency (CFE), specific energy absorption (SEA) has a maximum increase of 40.71%, 49.03% and 49.82%, respectively. In addition, Co-Co-inner-2 has a considerable interaction effect, which increases its energy absorption by 249.77%. However, although the gradient configuration effectively improves the SEA and MCF of the tubular structure, it brings an increase in IPCF. The SEA capacity of the corrugated inner rib reinforced tubular structures in this work is 27.12–56.77 J/g, which shows a satisfactory weight efficiency. The proposed structures can provide a useful reference for energy absorption devices in the national defense, aerospace and automotive industries.

Crashworthiness Analysis of Vehicle Crash-Box Filled with Aluminium Foam

Lightweight, robust, and anti-rust properties of aluminium foam might be a solution for reducing the effect of traffic accidents and for minimum fuel consumption. This research investigated the crashworthiness of vehicle crash-box filled with aluminum foam by varying its cross-sectional structure and its loading angle such as 0°, 10°, 20°, 30°. The variations consisted of structures for example single wall foam filled and double wall foam filled. The material used to construct the wall was Aluminum Alloy 2024 and Aluminium foam. The finite element model using Abaqus CAE Software was operated for both designing the crash-box and analyzing its crashworthiness. Some parameters were determined To obtain the best crash-box design, the finite element analysis was carried on total energy absorption, specific energy absorption, maximum load, average load, and crush-force efficiency. Double wall foam filled crash-box was shown to have better energy absorption ability and this structure of crush box is considered fpr vehicle structure in future.

Experimental investigation and crashworthiness analysis of 3D printed carbon PA automobile bumper to improve energy absorption by using LS-DYNA

This research work aimed to enhance the crashworthiness of the existing automobile bumper to minimize crash injuries. As per the simulation results the weight of the carbon polyamide-based bumper is reduced in comparison with the existing steel bumper by 9.7 kg or 47.5%, with this reduction in weight 38% increase in fuel economy has been estimated. The energy absorption capability of carbon polyamide bumper is improved from the existing steel and aluminum bumper by 11.15% and 16.3% respectively and with this modification, the impact force is reduced from the existing steel bumper, which has 4.87 kN and aluminum alloy bumper, which has 4.10–1.86 kN. The crashworthiness parameter result analysis showed that the corrugated bumper geometry had a structural energy absorption (SEA), total energy absorption (TEA), and crush force efficiency (CFE) of 103.28 J/kg, 911 J, and 77.99%, which is higher than the hallow bumper geometry of 102.4 J/kg, 847 J, and 65.83% respectively. In addition to that, as the thickness of carbon polyamide bumper reduced from 4 mm to 3.5, 3, and 2.5 mm, deformation increased with a small rate from 13.5 mm to 16.7, 18.52, and 22.04 mm.

Crushing behaviour of corrugated tilted honeycomb core inspired by plant stem

In this study, a new corrugated tilted honeycomb (CTH) core for sandwich structure is proposed by implementing the corrugated and tapered shape inspired by plant stems. Its crushing responses and energy absorption capacity are numerically investigated by using finite element software LS-DYNA. This study aims to propose an effective energy-absorbing core with a high energy-absorbing capacity and high crushing force efficiency. The crushing and energy absorption efficiencies of the proposed CTH cores are evaluated by comparing them with those of the commercially available cores such as square honeycomb core and aluminium foam of the same mass. The crushing performances of each core are evaluated by using the key indicators of the energy-absorbing structure such as the peak crushing force (PCF), mean crushing force (MCF), crushing force efficiency (CFE), and the specific energy absorption capacity (SEA). The effects of the crushing speed, tilted angle, and relative density on the crushing behaviour of the proposed CTH core are also investigated. It is found that under various crushing speeds, the proposed CTH core has a lower PCF, a higher MCF, CFE, and SEA than the conventional square honeycomb core and aluminium foam of the same mass. Furthermore, the CTH core has higher CFE and SEA than most of the existing structural forms of cores with similar relative density. The CTH core with two corrugations (C2) has a significantly improved SEA, which is four times higher than aluminium foam, up to 142% higher than the primitive structure, and 46% higher than the square antiprism structure, showing an excellent performing core for the energy-absorbing sandwich structures.

Study and optimization of energy absorption characteristics of a new concave polygon tube

To improve the energy absorption characteristics of the traditional convex polygonal tube and the existing concave polygonal tube, a new evolutionary scheme for the concave polygonal tube was proposed. The energy absorption characteristics of different concave tubes evolved from the common scheme (Scheme-I) and the new evolution scheme (Scheme-II) were studied through quasi-static compression experiments and numerical simulations. The results show that under the same mass, the concave polygonal tube evolved by Scheme-II has better energy absorption characteristics. The folded half-wavelength is smaller at the same compression distance, and compared with the traditional pentagon tube, the energy absorption (EA) of the pentagon concave of Scheme-II (N5E-CT) is improved by 218%, and the crushing force efficiency (CFE) is improved by 69%. Secondly, the mean crushing force of convex and concave tubes is derived and verified by the folded element theory. The mode of deformation of concave tubes under different structural sizes was investigated, and the size range within which the concave tube can remain stable was obtained. In addition, the evolution of the specific energy absorption (SEA) of the concave tubes was explored, and the SEA and the number of structural sides (N) show a trend of first increasing and then decreasing. Finally, the multi-objective optimization of the pentagon concave tube with excellent energy absorption characteristics was conducted, and the initial peak crushing force of the optimized structure was reduced by 19.92%.

Crushing responses and energy absorption of bionic inspired corrugated honeycombs

To improve the energy absorption of traditional structures, impact resistant natural materials are usually mimicked to develop novel structures with desirable energy absorption. In this work, inspired by the unique 3D corrugated microstructure of vascular bundles in pomelo peel, a new design of honeycomb structure with corrugated characteristics is proposed. Further, motivated by special nodal bulkhead architecture of bamboo, layered honeycombs with diaphragms are designed and fabrication by metal 3D printing technology. The quasi-static and dynamic crushing responses and energy absorption characteristics of six types of bio-inspirational honeycombs (ISWH, LSWH, ISCH, LSCH, IPCH and LPCH) are studied using quasi-static testing machine and dynamic drop-weight impact experimental systems. To investigate the effect of impact speed on the crashworthiness performance of the honeycombs, the tests of the honeycombs impacted by the drop-weight with two different mass (106.07 and 59.60 Kg) and three impact velocity (V1=6.23, V2=8.82 and V3=11.77 m/s), respectively, are performed. The experimental results indicate that the crush failure mode of the layered honeycombs is more regular than that of the integrated honeycombs. Failure of all layered honeycombs occurs first at the junction of the honeycomb and diaphragms. Under impact loading, the layered corrugated wall honeycombs exhibit a greater final crushing distance than their corresponding integrated honeycombs. The design of corrugated wall can effectively reduce the initial peak force of the integrated honeycombs, while the layered honeycomb design also facilitates the reduction of the initial peak force, thus avoiding damage to personnel or equipment from excessive peak collision forces. The layered design will reduce the specific energy absorption of the integrated honeycombs in most cases, but a reasonable combination of layered and corrugated wall design can also effectively increase the specific energy absorption of the honeycombs under a specific loading speed. And, the layered design can also effectively improve the crush force efficiency of the corresponding integrated honeycombs.

On the crashworthiness performance of thin-walled circular tubes: Effect of diameter and thickness

Thin-walled metal structures are known as an effective solution in absorbing impact energy and reducing the resulting reaction forces. The design of energy absorbers with higher energy absorption capability, lower weight and reaction forces, as well as lower manufacturing cost, has always been of interest. In this study, the effects of diameter and thickness of thin-walled Aluminum tubes on different crashworthiness criteria were investigated. To this end, different geometries were examined by simulating the uniaxial compressive test applying the finite element method. The results revealed that the optimal diameter for a simple circular tube (SCT), assuming constant length and thickness, is the smallest diameter in terms of resistance to global buckling. The SCT with an optimal diameter has the highest specific energy absorption (SEA), the lowest maximum crushing force ( F max ), and the highest crushing force efficiency (CFE). Moreover, in this study, the effect of thickness on the tubular absorber performance was numerically investigated according to four criteria: SEA, F max , CFE, and energy absorption (EA), and the optimal dimensions were obtained. Based on the results, increasing the thickness increases CFE, and increasing the ratio of thickness to diameter (t/D) increases SEA and CFE. Eventually, by applying the regression analysis, two equations were presented to calculate F max and CFE, which can be used to predict the performance of thin-walled metal tubes.

Study on the crashworthiness of star-shaped multicellular tubes

Based on the conventional star-shaped tube, a star-shaped multicellular tube was proposed and designed; finite element modeling was carried out using Abaqus/Explicit software, and the accuracy of the finite element model was verified under axial impact, the crashworthiness study shows that the star-shaped multicellular tube is significantly improved compared to the conventional star-shaped tube for the same wall thickness and same mass conditions. Namely, for the same wall thickness conditions, the energy absorption of the star-shaped quadrangular multicellular tube (SSMT-4-140°) is 1.77 times that of the star-shaped quadrangular tube (SST-4-140°), and the crush force efficiency is 1.24 times that of SST-4-140°; at the same mass, the energy absorption of SSMT-4-140° is 1.17 times that of SST-4-140°, and the crush force efficiency is 1.14 times that of SST-4-140°. Subsequently, the parametric study of the number of corners N, angle between two adjacent corners θ°, and wall thickness on the star-shaped multicellular tube was systematically carried out. The results of this paper can provide valuable information toward the innovative design of multicell tube structures.

Energy absorption characteristics of the bionic lotus petiole structure under transverse load

Porous structures are often used as energy absorbing devices due to their light weight and high strength; therefore, the mechanical properties and collapse behavior of porous structures under various loads have attracted much attention. In this paper, two bionic lotus petiole structures: 12-wells original structure (Os-12w) and 13-wells original structure (Os-13w) are proposed to improve the energy absorption properties of porous structures, which are inspired by the light weight and collapse resistance of lotus petiole. Then a comparative study of Os-12w, Os-13w, hollow square tube and hollow circular tube based on quasi-static mechanical experimentally(loading speed is 3 mm/min) validated finite element models was carried out to explore the energy absorption characteristics of different structures under lateral loading. The results showed that the specific energy absorption (SEA) of Os-12w and Os-13w increased by about 88.9% and 77.8%, respectively, and the crushing force efficiency (CFE) increased by about 178.8% and 178%, respectively, compared with the hollow square tube. Compared with the hollow circular tube, the peak crushing force (PCF) of Os-12w and Os-13w were reduced by about 28.2% and 36.8%, respectively. Collectively, Os-12w has a greater energy absorption potential than Os-13w. The simulation results of the experiment explain why the energy absorption performance of the bionic structure is better than that of the hollow tube. Then, through further simulation analysis, the effects of the bearing angle and quarter windmill-like structural parameters on the energy absorption characteristics of Os-12w were explored. Valuable suggestions and guidance are provided for the subsequent development of thin-walled porous structures.