On in-plane crushing behavior of an improved double-arrow auxetic metamaterial with two-step deformation mode

An improved double-arrow auxetic honeycomb metamaterial (MDAH) with two-step deformation mode was proposed and manufactured, and its in-plane crushing behavior was studied experimentally, numerically and theoretically. Quasi-static compression experiments were carried out to obtain the deformation modes and stress-strain response. The reliability of the numerical simulation was verified by experimental results. Experiments and numerical simulations have shown that MDAH exhibits a two-step deformation mode of first buckling deformation and then shrinkage deformation, with double-plateau stress characteristics. The provided theoretical results of plateau stresses are in good agreement with experimental and numerical simulation results. The effects of geometric parameters on the in-plane crushing behaviors of MDAH were further discussed through numerical simulation and theoretical analysis. The results indicate that the multi-step deformation mode of MDAH is related to the thickness and angle design of inclined rod. A suitable design can result in a stable two-step deformation mode and exhibit a negative Poisson's ratio effect. The MDAH structure has the characteristic of Poisson's ratio from positive to negative. The deformation mode and mechanical response can be regulated by changing the geometric parameters of MDAH. Compared to traditional double-arrow structures, MDAH has better energy absorption capacity. The present research can provide a new design strategy of auxetic metamaterial with deformation mode conversion and improved energy absorption efficiency.