On the out-of-plane crashworthiness of incorporating hierarchy and gradient into hexagonal honeycomb

Hierarchical design and gradient design have proven to be effective in improving the crashworthiness of honeycombs. In this study, a novel graded hierarchical hexagonal honeycomb (GHHH) is proposed by introducing wall thickness variation into the vertex-based hierarchical hexagonal honeycomb (VHHH). The VHHH is obtained by replacing every vertex of the regular hexagonal honeycomb (RHH) with a smaller hexagon. Numerical simulations and theoretical analysis are performed to study the crashworthiness performance of GHHH under the out-of-plane impact. The numerical results show that the specific energy absorption (SEA) of GHHH can be 146.09%, 39.01%, and 50.23% higher than that of RHH, VHHH, and graded hexagonal honeycomb (GHH), respectively, while their peak stresses are nearly the same. In addition, a theoretical model for the plateau stress of GHHH is developed, and the theoretical values show good consistency with numerical results of GHHH with in-extensional mode. The findings of this study provide an effective guideline for the design of honeycombs with enhanced crashworthiness.

Automated summary

Hierarchical design and gradient design are effective in improving the crashworthiness of honeycombs. This study proposes a novel graded hierarchical hexagonal honeycomb (GHHH) by introducing wall thickness variation into the vertex-based hierarchical hexagonal honeycomb (VHHH). Numerical simulations and theoretical analysis are used to study the crashworthiness performance of GHHH under out-of-plane impact. The findings provide effective guidelines for the design of honeycombs with enhanced crashworthiness.