In-plane compression behaviors of the auxetic star honeycomb: Experimental and numerical simulation

Abstract In this study, two types of star honeycombs with different cell-wall angles were fabricated by additive manufacturing technology for in-plane compression tests. Experiment results show that the cell-wall angle has no evident effect on the deformation modes, but the small cell-wall angle can improve the energy absorption capacity of star honeycombs. In addition, the unilateral horizontal maximum strain (UHMS) is proposed to evaluate the deformation stability of the honeycomb. Subsequently, numerical simulations are conducted to further investigate the influences of macro and micro geometric parameters on the in-plane compression behavior of star honeycombs. The results show that reducing the orthogonal array ratio and length of the ligament can significantly enhance the deformation stability and energy absorption capacity. Moreover, in accordance with the deformation mechanisms of a typical cell, a theoretical model is established to predict the plateau stress of star honeycomb under quasi-static loading. The theoretical results are in good agreement with the simulation results. Finally, three types of improved star honeycombs (ISH) are constructed by adjusting the ligament length, which improved the specific energy absorption by 30% compared with the classic star honeycomb. Besides, the ISH-II exhibits a stable deformation mode with a significant NPR effect. The results are expected to provide references for designing and optimizing the star honeycomb structure.