Characterization of energy absorption of a novel hierarchically nested self-similar multicellular circular tube

Thin-walled structures are increasingly favored for impact protection due to their lightweight nature and inherent crashworthiness. To develop energy-absorbing structures with enhanced performance, this study introduces a novel hierarchically nested self-similar multicellular circular tube (HNx) designed through self-similar fractal principles. A comparative analysis of the crashworthiness indices between the HNx structure and conventional round tubes indicates that the crashworthiness of the higher-order HNx structure surpasses that of conventional round tubes, both at equivalent mass and wall thickness. Notably, the energy absorption capacity of the HNx structure is improved by a factor of 30.14 relative to conventional round tubes with the same wall thickness. Further parametric analyses, examining variables such as wall thickness, wall thickness distribution of different reinforcing rib walls, and topology, demonstrate that these factors significantly influence the performance of hierarchical nested self-similar polygon-cellular circular tubes. In particular, 3-order structure of hierarchically nested hexagons (HNH-PO3) achieves a crashworthiness efficiency (CFE) as high as 90.64% at a thickness of 0.7 mm. Finally, the superior energy absorption performance of the proposed nested self-similar multicellular circular tube is validated through comparisons with other multicellular tube designs.