Study on impact resistance of biomimetic thin-walled structures with gradient design for automotive protective components

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.