On lateral crashworthiness of aluminum/composite hybrid structures

Abstract

To improve the lightweight and crashworthiness in vehicular engineering, there has been growing interests in metal/composite hybrid configuration, which is relatively newer than traditional metallic or composite structures. It is of vital importance to understand lateral crushing behaviors of hybrid system to gain maximum benefits from the structural configuration. In this present study, quasi-static lateral compression tests were carried out experimentally to investigate the transverse failure modes and crashworthiness characteristics of four different circular hybrid tubes made of either aluminum/carbon fiber reinforced plastics (CFRP) or aluminum/glass fiber reinforced plastics (GFRP) materials. From the experiments, it is found that the load carrying capacity of the aluminum/composite hybrid tubes with an inner composite tube was substantially higher than that of hybrid tubes with an outer composite counterpart. This is due to the fact that more significant delamination was initiated and propagated around the inner composite tube under transverse loading, which improved its lateral crushing characteristics. The interactive effects between single aluminum tube and single composite (CFRP or GFRP) tube was also investigated; and it is found that the specific energy absorption (SEA) of hybrid tube AL-T2-CF-P8 (2.41 J/g) and AL-T2-GF-P8 (2.27 J/g) were 58% and 47% higher than the sum of single aluminum tube and single composite tube alone, respectively. Based upon the experimental results, the finite element (FE) models were developed and validated to further explore the effects of hybrid ratios (i.e. aluminum vs. CFRP/GFRP of 4:0, 3:1, 2:2, 1:3 and 0:4) and stacking sequence on lateral crashworthiness. It is found that the aluminum thickness of a higher-ratio configuration can largely improve the load carrying and energy absorption capacities under lateral compression. For the six different stacking sequences considered here, the hybrid tubes with a symmetrical configurations [CF-P4-AL-T1]s and [GF-P4-AL-T1]s are of the best crashworthiness performance with the highest SEA of 3.43 J/g and 3.29 J/g, respectively. This study provides thorough understanding of the aluminum/composite hybrid tube subject to transverse crushing load, and would be of considerable implication to vehicular applications.