Sub-structure Geometry Effect on Energy Absorption Ability of Hierarchical Honeycomb under Crushing

Abstract

Honeycomb structures are stiff and light weight composite structures which show good energy absorption. Hierarchical honeycomb structures which are bio-inspired innovative form of honeycomb structure, are used for energy absorption applications. The crashworthiness of hierarchical honeycomb structures is function of sub-structure geometry. In the present investigation, crushing of vertex based hierarchical honeycomb with regular polygonal (n=3, 6, 9, 12, 15) and circular substructures is analysed using nonlinear explicit finite element code LS-dyna in both in-plane and out of plane directions. Effect of different sub-structure geometry on crashworthiness of vertex based hierarchical honeycomb is studied. Further a parametric analysis is performed to investigate the size effect of sub-structure on crashworthiness of hierarchical honeycombs, for every considered substructure geometry. To investigate the effect of crushing velocity on energy absorption similar analyses are performed at higher crushing velocity. In case of in-plane crushing, vertex based hierarchical honeycomb with large sized triangular sub-structure is found to have best energy absorption compared to other hierarchical honeycombs. While in case of out of plane crushing, vertex based hierarchical honeycomb with small sized hexagonal sub-structure is found to have better energy absorption among compared to other hierarchical honeycombs. An improvement in energy absorption of hierarchical honeycombs is found in both in-plane and out of plane crushing at higher crushing velocity.