In-plane dynamic crushing of a novel gradient square honeycomb with enhanced energy absorption

Due to the unstable structural characteristics of square cell elements, square honeycombs undergo slip deformation to the sides when the honeycomb is impacted at middle and low velocities, and consequently, the energy absorption capacities are low. To improve the energy absorption and modify the dynamic crushing behavior of the square honeycomb, a novel square honeycomb was proposed in which rods are added to the interior of the square cell elements. Subsequently, two graded gradient honeycombs and a “buffer” honeycomb were established based on the novel square unit cell, and their energy absorption properties were investigated. Through numerical simulations of the in-plane impact, it was demonstrated that one of the gradient square honeycombs exhibited the best specific energy absorption (34.92% higher than that of the square honeycomb) under low-velocity crushing, and the buffered square honeycomb showed the best crushing force efficiency (218.68% larger than that of the square honeycomb) for a mid-velocity collision. Furthermore, the slip degree of the honeycomb deformation mode was strongly inhibited for one of the novel square honeycombs, which exhibited the zero Poisson ratio effect. In addition, the effects of various factors, such as the geometric configuration and impact velocity, on the energy absorption performance were explored. This study offers novel ideas for improving the abilities of traditional honeycomb structures.