Mechanical characteristics of additive manufactured biomimetic gradient circular honeycombs with nested strategy under static and dynamic loading

Inspired by the microstructure of bamboo and the membrane wing structure of bats in nature, this study proposes nested self-similar gradient circular honeycomb (WNSGH) and nested non-self-similar gradient circular honeycomb (SNNGH). The deformation patterns and energy absorption properties of WNSGH and SNNGH under quasi-static compression, drop weight impact and Kolsky dynamic impact loading are systematically investigated using both experimental and finite element methods. The energy absorption mechanisms of the representative unit cells are elucidated through a series of finite element calculations. The results from both experimental studies and numerical simulations demonstrated that the nested gradient strategy could significantly enhance the specific energy absorption (SEA) of regular circular honeycomb (RCH). Specifically, under quasi-static loading, WNSGH and SNNGH exhibited increases of 66.8 % and 85 %, respectively, and improvements of 53.4 % and 14 %, respectively, under Kolsky bar dynamic impact loading. The deformation patterns of the two gradient honeycombs were found to be sensitive to the loading rate. Further findings indicated that the energy absorption performance of WNSGH and SNNGH outperformed many other existing circular honeycomb structures with different gradient strategies.