Conceptual Design and Parametric Optimization of a New Multileveled Horsetail Structure for Bicycle Helmets

This study aims to explore the feasibility of using a structure inspired by the features of horsetail and human spine as the potential helmet liner, targeting at mitigation of acceleration‐induced injuries, which includes rotational acceleration that focused by many researchers due to its dominance in causing severe brain injuries when cycling crashes happen. Evaluation of the compressive and shear performance of the new horsetail liner structure, as well as the material characterization of expanded polystyrene foam and thermoplastic polyurethane, has been conducted using both experimental and numerical means. To come up with the best design configuration of the horsetail liner structure, a parametric study is also conducted to investigate the effect of individual geometrical variables in the design. The results show that the optimal bioinspired horsetail structure is capable in reducing kinetic energy induced by both linear and rotational accelerations, demonstrating a potential application of this structure as a helmet liner. Suggestions on how to implement this horsetail liner structure into an actual commercial helmet are also made in this study.