Crushing resistance and energy absorption of pomelo peel inspired hierarchical honeycomb

Hierarchical materials born of variable natural cellular and intricate architecture are demonstrated to have the potential to achieve outstanding mechanical properties, thus make them excellent constituents for impact protection. Inspired by the unique microstructure of pomelo peel, this study constructed a novel hierarchical honeycomb and investigated the crushing resistance along with energy absorption capabilities of such structural materials. An integrated analytical-numerical approach was developed to fully elucidate the underlying quantitative structure-property relations by parametric studies on the evaluation of different hierarchical orders and equivalent thickness. It is revealed that the deformation modes of pomelo peel inspired honeycomb are governed by the geometric parameter-equivalent thickness, where three deformation modes (hexagonal mode, transitional mode and coin mode) and two localized band (V mode and I mode) can be observed under out-of-plane and in-plane crushing, respectively. Additionally, in conjunction with theoretical and numerical studies, improved crushing resistance and energy absorption properties of the pomelo peel inspired honeycomb can be obtained via increase of structural hierarchy and variation of geometric dimensions. The crushing resistance criteria, SEA (specific energy absorption) and equivalent plateau stress of hierarchical honeycomb, can be enhanced up to 1.5 and 2.5 times than its counterpart for traditional honeycomb under out-of-plane and in-plane crushing, respectively. The promising results of pomelo peel inspired honeycomb may exhibit a novel perspective on providing the superior mechanical properties of natural cellular materials and offer insights for applications of bio-inspired engineering materials.