Axial Collapse Characteristics of Aluminum/CFRP Compound Circular Tubes

Aluminum or CFRP (Carbon Fiber Reinforced Plastics) tube subjected to axial loading sustains load, and absorbs energy during axial collapse. The aluminum tube absorbs energy by stable plastic deformation, while the CFRP tube with higher specific strength and stiffness than those of the aluminum tube absorbs energy by unstable brittle failure. To achieve a synergy effect by combining the two members, aluminum/CFRP compound tubes were manufactured, which are composed of aluminum tubes wrapped with CFRP outside aluminum tubes with different fiber orientation angle of CFRP and number of plies. The axial quasi-static collapse tests were performed for the tubes. The collapse characteristics of the tubes were compared with those of respective aluminum tube and CFRP circular tube. Test results showed that the collapse of the aluminum/CFRP tubes complemented unstable brittle failure of the CFRP tube due to the ductile characteristics of the inner aluminum tube. The collapse modes and the absorbed energy were influenced by the fiber orientation angle of CFRP and the number of plies. The absorbed energy per unit mass, which is in the light-weigh aspect, was higher in the aluminum/CFRP compound tube than in the aluminum tube or the CFRP tube alone.