Dynamic crash responses of bio-inspired aluminum honeycomb sandwich structures with CFRP panels

Nature has provided us with extraordinary resources to tackle design challenges facing in modern society nowadays. The multistate structures inspired by animal shell have proven effective to improve the impact resistance of composite laminate. This study aims to identify the crash responses and crashworthiness characteristics of bio-inspired sandwich structures composed of carbon fiber reinforced plastic (CFRP) panels and aluminum honeycomb. The crash responses, failure mode as well as the effects of core side length, height and impact velocity on peak load and energy absorption were explored herein. The differences of crashworthiness characteristics between the CFRP aluminum honeycomb sandwiches and bare CFRP panel were quantified. Two typical load-displacement relations, namely single-peak and double-hump curves, were observed in the tests. It was noted in the energy-displacement curve, where the slopes corresponding to the failure stages of the upper and lower face-sheets, were greater than that in the honeycomb failure stage, indicating that the bare aluminum honeycomb was of lower energy absorption capacity than the CFRP face-sheet. By comparison, the honeycomb filling was an effective way to improve the impact resistance of CFRP structure, yielding higher energy absorption and lower peak load during the impact. It was also found that the crashworthiness characteristics were more sensitive to the core length than to the core height; and the specific energy absorption (SEA) varied insignificantly with the increase in the core height. It was noted that the peak load, absorbed energy and SEA increased significantly under high impact velocity.