Experimental study on out-of-plane mechanical and energy absorption properties of combined hexagonal aluminum honeycombs under dynamic impact

This paper experimentally studied the dynamic mechanical and energy absorption responses of three types of samples: single-layer hexagonal aluminum honeycomb, and combined hexagonal aluminum honeycombs at two stacking angles (0 degrees and 90 degrees). The combined honeycombs are composed of two-layered and nonpartitioned honeycombs. Dynamic experiments were conducted using a high-pressure gas-gun testing system at impact velocities of 30-70 m/s. Results showed that dynamic response of combined honeycombs mainly included cutting and buckling processes. The cutting plateau stress increased at a higher rate increased with impact velocity, but reached a lower final value in the 0 degrees-layered honeycombs than in the 90 degrees-layered honeycombs. The buckling plateau stress of the two combined honeycombs were almost equal, and approximately 1.5-2 times of their quasi-static values. Besides, a dimensionally consistent empirical formula was proposed to describe the effects of the honeycomb density and strain rate on the plateau stresses. It concluded that the energy absorption capacity was highest in the 90 degrees-layered honeycombs and lowest in the single-layer honeycomb. Finally, the energy absorption mechanisms of the two combined honeycombs were discussed. (c) 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).