Dynamic crushing analysis of a circular honeycomb with leaf vein branched characteristic

Abstract

For further improving the mechanical properties of the traditional honeycomb structure, a new excellent energy absorption structure named as the leaf vein branched honeycomb (LVBH) is proposed based on lotus leaf vein branched structure. The in-plane dynamic crushing of LVBH is numerically studied by LS-DYNA. Meanwhile, the crushing behavior of the regular circular honeycomb is carried out for comparison. The introduction of leaf vein branched characteristics affects the local deformation zone and the deformation mechanism of LVBHs can be classified into three categories: quasi-static mode, transition mode and dynamic mode. The mode classification map is further given. The comparison indicates that LVBH has better energy absorption performance with 79.94% higher specific energy absorption per unit mass (SEAm) than regular circular honeycomb (RCH). Following that, the influence of microstructure, relative density and crushing velocity on the energy absorbing characteristics of LVBH is systematically studied. The LVBHs with moderate structural parameters exhibit better mechanical properties. The quasi-static plateau stress depends upon the unit-cell configuration. Based on one-dimensional shock theory, the empirical equations of dynamic plateau stress for LVBHs with different relative densities are given by using least-square fitting. Furthermore, the numerical results show that the part of the outer-circle and branch-vein cell walls have higher energy absorption efficiency. The specific energy absorption per unit mass(SEAm)of LVBH can increase by 12.4% through the thickness matching between main-vein and the branch-vein cell walls. The results of this study will be helpful to design a novel honeycomb structure with better energy absorption ability.