Mechanical Properties Of Hierarchical Honeycomb Under In-plane Impact

The porous material is a combination of a hole composed of a solid edge or solid surface,low thermal conductivity,high Young’s modulus and high-resistance strength,it is widely used in material packaging,automotive engineering,housing construction,turning engineering and aerospace,etc.It is found that the introduction of hierarchical structure into ordinary honeycomb structure will greatly enhance its strength and energy absorption capacity.The honeycomb structure can be designed,and its impact resistance and energy absorption capacity can be significantly improved by reasonably changing the first-order structure and second-order structure of the honeycomb.In this paper,the in-plane impact properties of two different shapes of hierarchical honeycombs are systematically studied by finite element software.The first honeycomb structure is composed of a regular hexagon and an enhanced double arrow,in which the regular hexagon is the primary structure and the enhanced double arrow honeycomb is the second-order structure.The second honeycomb structure is composed of diamond and regular triangle,in which the diamond is the first-order structure and the regular triangle is the second-order structure.The finite element simulation and theoretical analysis of the mechanical behavior under quasi-static load and impact load were carried out.According to the results of numerical simulation,the deformation mode,platform stress and energy absorption characteristics of the honeycombs are analyzed,and the theoretical failure formula is verified under different relative densities and different numbers of substructures.The results of theoretical analysis are in good agreement with those of numerical simulation.Finally,combined with momentum conservation,the analytical model of quasi-static collapse stress is extended to dynamic collapse process,and the theoretical formula is derived by deformation mode,and different densities and velocities are set to verify the results.The results show that the honeycomb with hierarchical structure has higher collapse stress and better energy absorption characteristics than the first-order honeycomb.