Motivated by stringent crash safety and lightweighting targets in passenger-car frontal structures, this study draws inspiration from horsetail cross-section and proposes a bio-inspired multi-gradient thin-walled tube. Axial wall-thickness and length gradients are simultaneously introduced to achieve continuously tunable stiffness and progressive energy absorption. Finite element simulations are systematically performed to investigate the mechanical response, deformation mode and energy absorption characteristics of the tube under axial and oblique impacts. The results reveal that the outer wall and central ribs dominate energy dissipation, and that the thickness gradient markedly modifies the load path while suppressing local instability. Compared with a uniform baseline, the optimally graded configuration increases the specific energy absorption by approximately 80% and the crush force efficiency by approximately 20%. This biomimetic design strategy provides a theoretical foundation and technical route for the parameter optimization of high-performance energy-absorbing components and demonstrates broad engineering applicability.
WangDLiS.Material selection decision-making method for multi-material lightweight automotive body driven by performance. Proc Inst Mech Eng Part L: J Mater Des Appl2022; 236: 730–746.
2.
HyderAAHoeCHijarM, et al. The political and social contexts of global road safety: challenges for the next decade. Lancet2022; 400: 127–136.
3.
LiSWangDWangS, et al. Structure–connection–performance integration lightweight optimisation design of multi-material automotive body skeleton. Struct Multidiscipl Optim2023; 66: 198.
4.
MuruganRDoutrePTVignatF.Design and analysis of an automotive crash box using strut-based lattice structures. J Comput Nonlinear Dyn2024; 19: 121006.
5.
QureshiOMBertocchiEQaiserZ, et al. Frequency embedded box beam crash absorbers under oblique impacts. Thin-Walled Struct2014; 75: 1–7.
6.
WangBZhouC.The imperfection-sensitivity of origami crash boxes. Int J Mech Sci2017; 121: 58–66.
7.
PanYXiongYDaiW, et al. Crush and crash analysis of an automotive battery-pack enclosure for lightweight design. Int J Crashworthiness2022; 27: 500–509.
8.
SandriniGChindamoDGadolaM, et al. Exploring the impact of vehicle lightweighting in terms of energy consumption: analysis and simulation on real driving cycle. Energies2024; 17: 6398.
9.
LiKZhangMZhangZ, et al. High performance realization of functionally graded materials based on integrated optimal design and additive manufacturing: a review. Int Mater Rev2025; 70: 497–547.
10.
XuTWuHXueF, et al. Structural design of stamping die of advanced high-strength steel part for automobile based on topology optimization with variable density method. Int J Adv Manuf Technol2022; 121: 8115–8125.
11.
HanLHeXNingY, et al. An aircraft structural risk assessment method considering fatigue crack propagation based on fatigue damage diagnosis and prognosis. Int J Fatigue2025; 190: 108650.
12.
SunYLiCWuH, et al. Simulation and lightweight design for the structure frame of a flying car. Epub ahead of print 1January2018.
13.
LiuZLiuW.Study on impact mechanical properties of reentrant bionic automotive energy absorbing box. Appl Bionics Biomech2023; 2023: 1–9.
14.
JacobGCFellersJFSimunovicS, et al. Energy absorption in polymer composites for automotive crashworthiness. J Compos Mater2002; 36: 813–850.
15.
LiuHZhangZLiuH, et al. Theoretical investigation on impact resistance and energy absorption of foams with nonlinearly varying density. Compos Part B Eng2017; 116: 76–88.
16.
AndrewJJSchneiderJUbaidJ, et al. Energy absorption characteristics of additively manufactured plate-lattices under low-velocity impact loading. Int J Impact Eng2021; 149: 103768.
17.
BaykasoğluCBaykasoğluATunay ÇetinM.A comparative study on crashworthiness of thin-walled tubes with functionally graded thickness under oblique impact loadings. Int J Crashworthiness2019; 24: 453–471.
18.
DuJHaoPLiL.Finite element analysis of energy absorption characteristics for biomimetic thin-walled multi-cellular structure inspired by horsetails. Mech Adv Mater Struct2022; 29: 6982–6993.
19.
TaoCZhouXLiuZ, et al. Crashworthiness study of 3D printed lattice reinforced thin-walled tube hybrid structures. Materials2023; 16: 1871.
20.
LeDNovakNArjunanA, et al. Crashworthiness of bio-inspired multi-stage nested multi-cell structures with foam core. Thin-Walled Struct2023; 182: 110245.
21.
MaFLiangHPuY, et al. Multi-objective optimization of crash box filled with three-dimensional cellular structure under multi-angle impact loading. Proc Inst Mech Eng Part D: J Automob Eng2021; 235: 2397–2412.
22.
AnandSAlderliestenRCastroSGP. Crashworthiness in preliminary design: mean crushing force prediction for closed-section thin-walled metallic structures. Int J Impact Eng2024; 188: 104946.
23.
ChenJLiELiQ, et al. Crashworthiness and optimization of novel concave thin-walled tubes. Compos Struct2022; 283: 115109.
24.
LiZXuWWangC, et al. Investigation on vibration characteristics of thin-walled steel structures under shock waves. Materials2023; 16: 4748.
25.
WangKSunGWangJ, et al. Reversible energy absorbing behaviors of shape-memory thin-walled structures. Eng Struct2023; 279: 115626.
26.
LiJZhangYKangY, et al. Characterization of energy absorption for side hierarchical structures under axial and oblique loading conditions. Thin-Walled Struct2021; 165: 107999.
27.
BaroutajiASajjiaMOlabiA-G.On the crashworthiness performance of thin-walled energy absorbers: recent advances and future developments. Thin-Walled Struct2017; 118: 137–163.
28.
GaoQLiaoW-H.Energy absorption of thin walled tube filled with gradient auxetic structures-theory and simulation. Int J Mech Sci2021; 201: 106475.
29.
KocabasGBYalcinkayaSCetinE, et al. Energy absorption of a novel lattice structure-filled multicell thin-walled tubes under axial and oblique loadings. Adv Eng Mater2024; 26: 2400483.
30.
LiDQinRXuJ, et al. Topology optimization of thin-walled tubes filled with lattice structures. Int J Mech Sci2022; 227: 107457.
31.
LiZChenRLuF.Comparative analysis of crashworthiness of empty and foam-filled thin-walled tubes. Thin-Walled Struct2018; 124: 343–349.
32.
GuoWYangLXuP, et al. Crashworthiness analysis of okra biomimetic corrugated multi-cellular structure. Int J Mech Sci2024; 280: 109459.
33.
CetinE.Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading. J Braz Soc Mech Sci Eng2024; 46: 607.
34.
ZhaoBLiuYLuH, et al. 3D printable, high energy-absorbing, biomimetic and fractal antler structures. Smart Mater Struct2025; 34: 025018.
35.
DuJHaoPLiuM, et al. Multi-cell energy-absorbing structures with hollow columns inspired by the beetle elytra. J Mater Sci2020; 55: 4279–4291.
36.
JianxunDChengzhouXZhengjianF, et al. Numerical investigation on energy absorption characteristics of impact-resistant lightweight structure of bio-mimetic micro aerial vehicle. Proc Inst Mech Eng Part L: J Mater Des Appl2024; 238: 1226–1238.
37.
DuJGeCXueC, et al. Numerical investigation on energy absorption characteristics and damage modes of biomimetic thin-walled structures in aircraft. Proc Inst Mech Eng Part L: J Mater Des Appl2025; 239: 2133–2142.
38.
JianxunD.Numerical and experimental research on energy absorption characteristics and damage modes of biomimetic anti-collision structures for micro aerial vehicles. Arab J Sci Eng2025; 50: 9307–9323.
39.
DuJXueCXiaoJ, et al. Failure modes and mechanical behavior of bioinspired CFRP mortise-tenon structures under tensile loading. Proc Inst Mech Eng Part L: J Mater Des Appl. Epub ahead of print 29October2025. DOI: 10.1177/14644207251388527.
40.
MohebbiMSAkbarzadehA.Development of equations for strain rate sensitivity of UFG aluminum as a function of strain rate. Int J Plast2017; 90: 167–176.
41.
BaykasoğluCBaykasoğluACetinE.Multi-objective crashworthiness optimization of square aluminum tubes with functionally graded BCC lattice structure filler. Int J Crashworthiness2024; 29: 80–94.
42.
HaNSPhamTMChenW, et al. Crashworthiness analysis of bio-inspired fractal tree-like multi-cell circular tubes under axial crushing. Thin-Walled Struct2021; 169: 108315.
43.
ChaudhuriRAOktemAS.Flattening effect of negative gaussian curvature on simply supported thick asymmetric cross-ply panels in the absence of surface-parallel edge restraints. J Aerosp Eng2020; 33: 04020073.
