Quasi-static compression response of a novel multi-step auxetic honeycomb with tunable transition strain

Auxetic honeycombs with multi-step deformation have received widespread attention due to their multi- functionality and superior mechanical properties. To improve the tunability of the auxetic honeycomb, a novel multi-step auxetic honeycomb (MSAH) is proposed by combining star-rhombic parts with crossed thin walls. MASH is characterized by multi-step deformation, and its stress-strain curve has three significant plateau stages. The strain during the transition between different deformation steps can be adjusted by designing unit cells with different geometrical parameters. In the compression process, the ordered contact of the cell walls of MASH is the critical reason for realizing the multi-step deformation. The quasi-static compression finite element model of MASH is established and verified by experiments. Quasi-static compression response and deformation mechanism of MASH are studied. Then, the effects of geometrical parameters on the compression response of MASH are investigated. The results show that the wall thickness has a greater effect on the compressive stress, and the cell- wall angle determines the deformation mode of MASH. Furthermore, the transition strain of MASH is theoretically analyzed and verified by numerical simulations. This study provides a reference for designing multi-step deformation honeycombs and applying multi-stage energy absorbers.