Dynamic crushing responses of bio-inspired re-entrant auxetic honeycombs under in-plane impact loading

Abstract In order to improve the impact energy absorption abilities and maintain good crushing load uniformity of auxetic honeycombs, a re-entrant arc-shaped honeycomb (RAH) model is proposed according to the concept of bio-inspired structure design. The in-plane impact resistances and absorbed-energy characteristics of bio-inspired auxetic RAHs subjected to a constant velocity crushing are numerically studied by using ABAQUS/EXPLICIT. It is shown that due to the introduction of re-entrant arc-shaped structures, the dynamic response curves of bio-inspired RAHs have better crushing load uniformity than conventional re-entrant honeycombs. Except for the relative density and impact velocity, the dynamic crushing behaviors of bio-inspired RAHs also depend upon the cell micro-structure parameters (e.g., the curvature). Based on the one-dimensional (1D) shock theory and absorbed-energy efficiency method, an empirical equation is deduced to evaluate the dynamic plateau stress of bio-inspired RAHs. The finite element (FE) results coincide well with those calculated by the empirical formulas. Moreover, the specific energy absorption (SEA) and energy dissipation rules of bio-inspired RAHs are discussed, which are also dependent on the curvature. These researches will provide technical support for the innovative structure design and dynamic optimization design of auxetic cellular structures.