Comparing and optimizing different bio-inspired crash box designs

A crash box design is developed to enhance the crash box’s abilities to absorb crash energy. Previous research has developed the crash box by adding filler material. Adding the filling material to the crash box will increase energy absorption. Aluminum honeycomb has a combination of lightweight mass and an ability to absorb crash energy. The addition of filler material to the crash box will also reduce the possibility of global bending in the crash box. The method of study is a computer simulation using ANSYS Academic software ver 18.1. This research used circular, square and hexagonal cross-section variations, which reached the same cross-sectional area design. Geometry model for the crash box and honeycomb filler is defined as crash box thickness (tc) 1.6 mm, honeycomb filler thickness (t) 0.5 mm for single layer and 1 mm for double layer and crash box length (l) 120 mm. The materials used were AA6063-T6 for crash boxes and AA3003 for honeycomb fillers. The test model consisted of two types, namely frontal load and oblique load test. The impactor velocity (v) is set to 15 m/s. The impactor and the fixed support are modeled as a rigid body, while the crash box is assumed as an elastic body. Observations were done by using the characteristics of deformation pattern and the absorption amount of produced energy due to the given loading model. Based on the deformation pattern results, it can be found that in the crash box model with square and hexagon honeycomb filler, the occurred deformation pattern was concertina, while the crash box with circular honeycomb filler was the mixed mode in the frontal load test. Regarding the oblique loads, the crash box remains to collapse the global bending on all models. Simulation results with the frontal load test model found that the crash box with circle-shaped honeycomb has the highest energy absorption while the crash box with hexagonal honeycomb filler has the highest Specific Energy Absorption (SEA). In the oblique load test, it was found that the crash box with hexagonal honeycomb filler has the highest energy absorption and SEA. By comparing the hexagonal crash box model with and without honeycomb filler, it is noted that the hexagonal crash box with honeycomb filler has higher Crash Force Efficiency

This study presents a comprehensive experimental and computational investigation of the quasi-static axial compression behavior of glass fiber-reinforced polymer/ polypropylene (GFRP/PP) sandwich tubes inspired by bamboo and horsetail structures, designed for crashworthiness applications. The combination of these materials, due to their high strength-to-weight ratio, offers excellent energy absorption capabilities. To this end, firstly, single-hollow tubes were investigated numerically and experimentally. After ensuring the accuracy of the numerical results, many numerical sandwich tubes were simulated to investigate the effect of geometric parameters. Then, the numerical results such as peak crushing force (PCF) and specific energy absorption (SEA) were used as input data for learning of multi layers perceptron (MLP) algorithm network. Finally, using genetic algorithm showed the optimal specimen with t = 1.2mm, h = 80mm, and 3 GFRP sub-core tubes has the optimal crashworthiness performance. This specimen exhibits the optimal PCF (18.24 kN) and SEA (7.8J/g) values compared with the other samples. In addition, a techno-economic assessment was conducted using the Net Present Value (NPV) method to determine the long-term financial viability of replacing traditional materials with GFRP/PP. This approach is an essential step in bridging the gap between technical performance and industrial applicability. The results revealed that while GFRP/PP crash tubes offer superior weight-specific energy absorption, their economic competitiveness varies by reference material. Specifically, replacing steel and aluminum crash boxes with GFRP/PP results in positive net present values of $322.49 and $240.27 per vehicle, respectively, highlighting clear financial and environmental benefits.

Crash box design as one of the passive safety components in a vehicle had been developed to enhance energy absorption. Initial fold on the crash box is set to facilitate folding during the crash. The aims of this study is to investigate the initial folded crash box with length to thickness ratio subjected to frontal test. The frontal test is modelled by using finite element analysis. Through computer simulation using 9 models, the obtained result was used to provide the better design of crash box. The variations in this study were length to thickness ratio of crash box with length of tube (L) = 115; 132.5; 150 mm and the thickness of tube (t) = 1.6; 2.0; 2.5 mm. The crash box material was assumed as bilinear isotropic hardening material. The velocity used in the simulations was 7.67 m/s with impact mass of 103 kg. Based on the results, it can be shown that 1st model to 8th model produce deformation pattern as concertina mode and 9th model has diamond mode. The 3rd model has the largest energy absorption with value 18.29 kJ.

Crashworthiness is related to the ability of a structure to reduce the effects of a collision risk of injury to passengers and the risk of damage to vital parts of the vehicle. Geometry design of crash box is one important parameter to increase crashworthiness performance by increasing energy absorption through progressive deformation. In previous studies, circular crash box absorbed higher energy than other geometry design. Besides that, another parameter is material design. In other studies, the hybrid model absorbs more energy with a less increasing mass. Hybrid crash box combine low-density and high-strength of composite materials with aluminium materials are affordable and ductile to increase energy absorption. This study aims to develop circular hybrid crash box by variating fibre orientation angle of composite and hybrid material configuration. Crash box design is investigated by using computer simulation with ANSYS Workbench. The crash box materials used are Carbon Toray T300 – Epoxy Resin (CCE) and Aluminium Alloy 6063 (AA6063). Eight of circular hybrid crash box models subjected to axial loading with a speed of 10 m/s. The frontal loading is modelled by setting impactor with mass of 100 kg. Energy absorption and deformation pattern were observed. The results showed that the Al-Ko45 model with orientation angle [45/- 45,-45/45]5 and hybrid material configuration of composite inside has highest energy absorption of 8.24 kJ. The deformation pattern in the aluminium part is mixed of concertina at the first stage then continued by diamond pattern, The deformation composite part is dominated by local buckling with transverse shearing. The fractions or folds of composite is functions like foam-filled filling folds of aluminium deformation to initiate progressive crushing folding that can increase the crashworthiness characteristic as the energy absorption.

Metal foams for improved energy absorption in passenger vehicles

Partially Alulight and Hydro Al closed-cell foam-filled commercial 1050H14 Al and 6061T4 Al crash boxes were optimised using the response surface methodology in order to maximise specific energy absorption (SEA). The quasi-static crushing of empty and filled crash boxes was simulated using LS-DYNA, and the results were further confirmed with experimental quasi-static crushing testing of empty and Alulight foam-filled commercial 1050H14 Al crash boxes. Results showed that partial foam filling of commercial crash boxes increased both SEA and mean load because of foam filler axial and lateral deformation in between the progressing folds of the crash box. Within the studied constraint range of box mean load, box wall thickness and foam filler density, the optimised Alulight and Hydro foam-filled 1050H14 and 6061T4 crash boxes resulted in 26%–40% increase in total energy absorption as compared with empty crash boxes. Considering the same weight basis, the use of a higher yield strength box wall material and higher plateau stresses of Al foam filler resulted in higher energy absorptions in partial foam-filled boxes at relatively low displacements.

This study presents a crashworthiness evaluation of a Parallel 5-Tube Circular Multi-Segment Crash Box with a cutting die trigger, designed to promote controlled progressive folding for high-speed railway applications. The crash box integrates four primary tubes and one secondary tube in a parallel configuration, featuring multi-segment wall thickness and a die-trigger mechanism designed to initiate controlled folding from the tube’s end. The die acts as a deformation initiator, guiding the folding sequence to occur progressively, thereby improving energy dissipation and reducing peak impact forces. Two impact models, namely the Cutting Die Model (CDM) and the Flat Model (FM), were employed to investigate the combined effects of trigger mechanism, multi-segment wall thickness, and impact direction using validated finite element simulations supported by quasi-static and drop-test experiments. Finite Element Analysis (FEA) simulations using ANSYS LS-DYNA were conducted to assess key crashworthiness indicators, including maximum crushing force (Fmax), energy absorption (EA), specific energy absorption (SEA), mean crushing force (Fmean), and crushing force efficiency (CFE). Experimental validation through quasi-static and drop tests confirmed the reliability of the simulation results. The findings reveal that the CDM configuration significantly outperforms the FM model, exhibiting lower Fmax and higher EA, SEA, and CFE values. Progressive folding initiated by the die mechanism enables more stable and efficient energy dissipation. Additionally, the impact direction influences deformation behavior, with the t₁–t₂ configuration yielding superior performance. These results demonstrate the effectiveness of the proposed crash box design in meeting the stringent safety and spatial requirements of modern railway systems.

The crease line formed in an origami-shaped crash box (OSCB) acts as a geometric imperfection and mode inducer. Such geometric imperfections make it possible to protect occupants by lowering the peak force in the event of a collision. The OSCB also shows desirable performance as a crashworthy structure by inducing a collapsing mode with excellent energy absorption. There are many studies on crash boxes with origami patterns applied, but few studies on performance optimisation. This article describes the structural optimisation of an OSCB to maximise the specific energy absorption (SEA) by setting the corner length c and module length l as design variables. Numerical and experimental investigations of the crashworthiness performance were conducted by comparing the optimised OSCB to a circular crash box (CCB), which is known to have the best SEA among straight tubes. The numerical and experimental results were in good agreement, with the optimised OSCB collapsing into the diamond mode. The results of the numerical comparison showed that the SEA and the crush force efficiency (CFE) of the optimised OSCB were increased by 5.94% and 115.58%, respectively. However, in a quasi-static axial crushing experiment, the SEA of the optimised OSCB was 10% lower than that of the CCB, and the CFE was increased by 88.5%. The optimised OSCB in this study displayed an improvement in the SEA compared to the reference OSCB, as well as a reduction in the difference from the CCB, indicating high maintenance performance of the CFE.

This study investigates the impact absorption performance of bamboo-inspired 3D-printed circular tubes in terms of infill type (grid, gyroid, honeycomb, Archimedean chords), infill ratio (10%, 20%, 30%, and 40%), wall thickness (0.8, 1.2, 1.6, and 2.0 mm), and inner diameter parameters. The structures designed using Taguchi L16 orthogonal design are printed with PLA material using FDM technology and evaluated by quasi-static compression tests. Peak crushing force (PCF), energy absorption (EA), and specific energy absorption (SEA) criteria are used to analyse crashworthiness performance. The experimental results showed that EA improves as the infill rate increases, but the gain decreases as the infill rate approaches 40% (SEA at 30% is better than that at 40%). By visualising the PCF and EA data relative to the utopia point (the lowest PCF and highest EA), GRID_T16F30D24, HCOMB_T08F30D22, and GRID_T12F20D22 are found to be the best-performing tubes. The grid and honeycomb infill types showed superiority at 20–30% infill rates and similar wall thicknesses. The Archimedean chords type performed poorly due to its tendency to fracture.

The crash box becomes a crucial component of the vehicle structure, special designed for energy-absorbing during collisions. This study aims to evaluate the performance of honeycomb structures in crash boxes and to investigate the deformation characteristics, energy absorption, and reaction force during crash tests. In this work, a novel crash box based on the hexagonal honeycomb structure with variations in the addition of circles at each hexagonal corner is proposed. The research configurations simulate a crushing test on the traditional honeycomb structure and variations CH 1, CH 2, CH 3 and CH 4. The honeycomb model was analyszed using different impactor velocity of 3 m/s and 4 m/s, with a mass of 500 kg. The result shows that increasing the size of the circle structures at each hexagonal honeycomb corner can increase crash energy absorption (EA). The CH 3 and CH 4 crash box structures offer the most increases in EA for each crash velocity than the traditional honeycomb. Higher impact velocities activate more stable progressive folding mechanisms in the honeycomb, thereby enhancing deformation efficiency during impact. The CH4 configuration exhibits higher SEA and MCF while maintaining a stable PCF, reflecting enhanced crashworthiness performance. This improvement is associated with progressive local buckling, which enables controlled and stable energy dissipation during impact. At a velocity of 3 m/s, the deformation pattern is consistent with previously reported studies, where the initial fold or fracture initiates in the middle of the honeycomb structure.

This paper aims at optimising the crashworthiness capabilities of hybrid S-shaped rails of an automotive body under oblique impact loading. In the optimisation process, geometrical parameters, material types and the length ratios of aluminium part to the whole length are taken as design variables. Kriging metamodel techniques are performed to predict the crashworthiness criteria of specific energy absorption (SEA) and peak crushing force (PCF). In the following multi-objective optimisation design (MOD), non-dominated sorting genetic algorithm (NSGA-II) is adopted to obtain maximum SEA capacity and minimum PCF of hybrid S-shaped rails. It is found that the optimum design for a specific load angle does not necessarily guarantee the best solution when the load angle changes. More importantly, the change of weighting factor for each load angle affects the Pareto front of such MOD considerably, and thus selecting proper weights is of great importance in the crashworthiness design of hybrid S-shaped rails.

Lightweight energy‐absorbing structures are critically needed across engineering sectors. Conventional energy‐absorbing structures have an initial peak crush force that is too high and insufficient lightweighting. This study integrates additive manufacturing with biomimetic design to develop bamboo‐inspired vascular bundle tubes(VBT). Specimens fabricated from multiple materials underwent quasi‐static axial and radial compression testing. The results demonstrate superior energy absorption performance in carbon fiber–reinforced Polyethylene Terephthalate Glycol (PETG/CF) specimens. Structural optimization incorporating bamboo‐mimetic axial vascular arrangements enhanced specific energy absorption (SEA) through improved biomimetic fidelity. Process parameter studies revealed that reducing the layer height from 200 to 100 μm simultaneously increased SEA and reduced peak crushing force (PCF) under both loading conditions. Axial loading increased SEA by 30% and reduced PCF by 15%. In contrast, radial loading resulted in a 15% increase in SEA and a 20% reduction in PCF. This work establishes a synergistic material‐structure‐process strategy for high‐performance bio‐inspired energy absorbers, advancing impact protection technology.

This study proposes a reinforcement learning-based multi-objective optimization framework for automotive energy-absorbing box structures, aiming to improve specific energy absorption (SEA) and reduce peak crushing force (PCF). A parametric model with adjustable folding angle, layer number, and multi-wall thicknesses is developed and integrated with automated modeling, simulation, and evaluation. An improved MO-SAC algorithm enables joint optimization of W2W and W2C structures. The agent explores optimal designs based on simulation feedback. Results show that the optimal 9-layer W2W structure with a 122.46° folding angle and wall thicknesses of 1.35 mm, 1.29 mm, and 1.47 mm achieves a 21.28% increase in SEA and a 12.59% decrease in PCF. This method offers a data-efficient and interpretable solution for structural optimization.

Crashworthiness design of functionally graded foam-filled multi-cell thin-walled structures

This study investigates the crashworthiness performance of novel crash box geometries inspired by the structural configuration of coconut tree trunks. Six models were analyzed, comprising four bio-inspired designs with square and circular cross-sections in single- and double-shell forms, along with two conventional hollow configurations. Numerical impact simulations, validated against experimental data, were conducted to evaluate force–time, force– displacement, and energy absorption responses. Results indicate that the introduction of internal reinforcement significantly enhances energy absorption, while circular geometries provide lower peak forces and more stable deformation. The findings highlight the potential of bio-inspired crash boxes for improved passenger vehicle safety.