In-plane dynamic crushing behaviors of a novel auxetic honeycomb with two plateau stress regions

Abstract

In order to obtain honeycomb structure with higher energy absorption capacity, a novel honeycomb is proposed by adding double arrowhead honeycomb (DAH) cells into star-shaped honeycomb (SSH), and therefore named as star-arrowhead honeycomb (SAH). An analytical model is built to investigate the in-plane elastic properties of the newly proposed honeycomb and the results are in good agreement with the finite element simulations. The in-plane dynamic crushing behaviors and energy absorption capabilities of SAH are studied systematically by finite element method and are compared with that of SSH and DAH. Two plateau stress regions in the stress–strain curves of SAH are observed under low-velocity impact loading, and the second plateau stress is over three times higher than the first one. The in-plane Poisson's ratio of SAH under static and high-velocity impact loading always shows negative value. However, the Poisson's ratio of SAH changes from negative to positive under low-velocity and medium-velocity impact loading. In addition, the Poisson's ratio of SSH and DAH are negative during the entire dynamic deformation processes. The results of finite element simulations show that SAH can absorb much more energy than SSH with the same relative densities under different impact velocities, especially under low-velocity impact loading. Furthermore, the effects of the cell wall thickness and the impact velocity on plateau stress of SAH are discussed, and therefore a deformation map is summarized. It can be concluded that SAH is a better choice for energy absorption. This study may provide a new design concept for the high performance honeycomb structure with multi plateau stress regions.