Microstructural effect of a novel re-entrant triangular honeycomb under dynamic crushing and different temperature

The effects of the microstructure on the energy absorption and crashworthiness of a novel honeycomb are examined in this study. By deforming two cell walls of a triangular honeycomb (TH) inward to various degrees, novel re-entrant triangular honeycombs (RTs) were designed. Two novel RT structures were considered—a regular RT (RRT) and a staggered RT (SRT)—to conduct a systematic investigation. The in-plane dynamic crushing behavior was studied though the nonlinear finite element method. The results show that the RTs had rich deformation modes under different impact velocities, in which the RRT exhibited a double-plateau stage and the SRT possessed a large negative Poisson’s ratio. Subsequently, the deformation mechanisms of the RTs were explained and the theoretical formula of RRT was deduced according to the energy conservation under low-velocity impact. As the same relative density, the RT exhibited a higher energy-absorbing capacity and crashworthiness for mid-velocity crushing, and this trend was amplified by the impact velocity. Finally, the apical angle and temperature had significant effects on the RT and TH. This work provides a novel concept for the investigation of the performances of honeycombs in various environments and the design of excellent lightweight energy absorbers.