Load characteristics of triangular honeycomb structures with self-similar hierarchical features.

• A novel self-similar hierarchical triangular honeycomb (SHTH) is developed. • The 3D metal printing technology is used to carry out the experimental research in this study. • The crashworthiness performances of SHTHs are investigated. • The theoretical models of SHTHs are established based on equivalent simplified collapse mode. Hierarchical structures and materials have attracted extensive attention due to their advantage in improving mechanical properties. Therefore, to design lightweight structures with superior mechanical properties, a novel self-similar hierarchical triangular honeycomb (SHTH) is developed by sequentially arranging the similar sub-triangles on the side of an ordinary triangular honeycomb (OTH) in this study. The crushing mechanism of SHTHs is investigated using experimental, numerical, and theoretical methods. The numerical simulation is verified by the experimental data of metal 3D printed specimens. Firstly, comparative studies on the crushing performances of the SHTH and the OTH are performed. The results demonstrate that the hierarchical configuration has great improvement in deformation mode and crashworthiness indicator for triangular honeycombs. Then, the crushing performances of SHTHs with different hierarchy factors and relative densities are discussed. The results show that the relative density and the hierarchy factor have significant effects on the in-plane mechanical behaviors of SHTHs. Moreover, the SHTHs exhibit better crashworthiness in the X-direction (i.e., along the side direction of the primary triangular cell) than in the Y-direction (i.e., normal to the side direction of the primary triangular cell), and the crushing performances of SHTHs are tunable by relative density and hierarchy factors. Finally, the theoretical models on the crushing responses of SHTHs are first derived based on equivalent simplified collapse mode and then verified by experimental and numerical data. The results further reveal the influence mechanism of hierarchical arrangement in improving the crushing performance of honeycomb structures, and a novel design concept for engineering collision protection is developed in this study. [ABSTRACT FROM AUTHOR]