Experiment and modified model for CFRP/steel hybrid tubes under the quasi-static transverse loading

Composite/metal hybrid structure has both the advantages of light weight and high strength of composite materials and the advantages of low cost and easy connection of metals, which has great prospects for automotive applications. It is significant to investigate the energy absorption characteristics and theoretical analysis of Composite/Metal hybrid structures under transverse loading. Our study uses the example of CFRP/steel hybrid tube to explore bending deformation behaviour and energy absorption characteristics of the structure by experiment and theoretical analysis based on three-point test. Here, the effects of different winding sequences and thickness (4-ply, 8-ply, and 12ply) of CFRP were performed at three-point bending test, and all specimens were guided by metal tubes to stabilise bending collapse, and the influence of winding sequences on energy absorption and bending resistance is greater than that of numbers of winding layers. The result showed that the specific energy absorption of CFRP/steel hybrid tube with [+/- 45 degrees/90 degrees/90 degrees](2) winding modes was the best, which was 21.4% higher than that of Large-Diameter (LD) steel tube. The bending theoretical model of composite/metal hybrid tube based on Poonaya's model was performed to predict bending behaviour of hybrid tube. The theoretical result is in good agreement with the experiments, and the bending collapse behaviour is related to the hinge lines formed by CFRP with different angles. The bending theoretical model was modified by considering the hardening behaviour of the material, and can be applied to study on bending behaviour of CFRP/metal hybrid tube by the validation of the CFRP/Al hybrid tube.