Experimental and analytical assessment of axial crushing of circular hybrid tubes under quasi-static load

In the present article, axial crushing behavior of circular aluminum/glass-epoxy hybrid tubes is studied experimentally and analytically. 48 quasi-static axial crushing experiments are carried out on bare metal and hybrid tubes to evaluate the effect of different parameters such as metal and composite wall thicknesses and stacking sequence of composite layers on the crashworthiness characteristics. The specimens are made in two types of layups including angle ply pattern [+/-theta](s) and multi angle ply pattern (different ply angles). The experimental results reveal that stacking sequence has a considerable effect on crashworthiness characteristics, for example for layup [90/0/0/90], the absorbed energy is more than three times of aluminum tube with the same aluminum wall thickness. Also the aforementioned layup has better energy absorption compared to [90/90/90/90] which has been previously proposed as the best layup. According to considerable effect of stacking sequence on the axial crushing behavior of hybrid tubes, an analytical model is developed by including fiber ply orientation of each composite layer and an expression is derived for the mean crushing load and fold length in terms of thicknesses of metal and composite walls and material properties of metal and composite. This model shows reasonably good agreement with experimental results. (C) 2012 Elsevier Ltd. All rights reserved.