On in-plane crushing behavior of a combined re-entrant double-arrow honeycomb

A novel re-entrant double-arrow honeycomb (RDAH) has been proposed and investigated by combining reentrant hexagonal honeycomb and double-arrow honeycomb. Quasi-static compression experiments of 3D printed samples in different loading directions were carried out. Deformation modes and stress-strain response have been explored and identified. The corresponding finite element (FE) models were established and verified, and the dynamic crushing behaviors of RDAH were further investigated by FE simulations. The results show that RDAH has three typical deformation modes under different impact velocities. When subjected to quasi-static loading and low-velocity impact along the horizontal wall, two stress plateau regions of the stress-strain curves can be observed, while there is only one stress plateau when loaded perpendicular to the horizontal wall. Based on deformation modes, theoretical models of plateau stresses of RDAH under low-velocity and highvelocity impact were further established. The theoretical results of the plateau stresses agree well with the FE simulation results. The effects of impact velocity and geometric parameters on densification strain, Poisson's ratio and energy absorption were also discussed. The results show that the RDAH exhibits obvious negative Poisson's ratio effect in both directions. The energy absorption of RDAH is higher when loaded along the horizontal wall and can be 29.45 % higher than the traditional RH structure. The energy absorption of RDAH increases with the decrease of inclined wall l1, the decrease of inclined angle theta (perpendicular the horizontal wall), and the increase of inclined angle theta (along the horizontal wall).