Impact energy absorption of bio-inspired tubular sections with structural hierarchy

Structural hierarchy in nature can be mimicked in order to develop novel composites and structures with desirable properties. In this study, hierarchy is introduced at multiple length scales into tubular sections that can be utilised as energy absorbing systems in various industries. The proposed hierarchical tubular section is inspired by the micro- to nano-architecture of biological materials, such as tendon and muscle, which can be mimicked by packing smaller tubes into a tube of a higher hierarchical level. The process can be repeated for creating tubular sections of higher orders of structural hierarchy, regardless of size or choice of materials. Numerical experiment has revealed that the impact energy absorption capability can be improved significantly when hierarchy is introduced and greater enhancement is achieved for higher-order hierarchical sections. A parametric study has been undertaken, and with the use of dimensionless parameters, the robustness and the generality of the phenomenon are demonstrated.