Crashworthiness of a bio-inspired hierarchical sine-wave unit reinforced circular tube

To enhance the energy absorption performance and load stability of thin-walled structures under axial impact, a circular tube reinforced by sine-wave units (CAS) was proposed. The design combines morphological inspiration from the continuously curved profile of the woodpecker beak with organizational inspiration from multiscale hierarchical structures in nature. The curved feature is represented by parameterized sinusoidal reinforcement units, which are recursively combined with circular tubes at progressively smaller spatial scales, sinusoidal reinforcement units with different hierarchical levels are embedded into a conventional circular tube to reconfigure load transfer paths and regulate collapse modes. Here, the finite element simulations combined with super-folding element theory are conducted to investigate the crashworthiness of this structure under quasi-static and dynamic loading, where the effects of hierarchical level, geometric parameters, and impact velocity on peak crushing force, mean crushing force, specific energy absorption, and load stability are systematically investigated. The results show that the hierarchical curved reinforcement design can effectively suppress unstable buckling, reduce peak crushing force, and significantly enhance energy absorption efficiency. This work provides a new strategy for designing thin-walled energy-absorbing structures for lightweight, high-efficiency crashworthy components in transportation, aerospace, and protective engineering applications.