Axial Crushing Behavior and Energy Absorption Capability of Al/CFRP Square Tubes for Light-Weights

An aluminum or CFRP (Carbon Fiber Reinforced Plastics) tube is representative light-weight materials but its axial collapse mechamism is different from each other. The aluminum tube absorbs energy by stable plastic deformation, while the CFRP tube absorbs energy by unstable brittle failure with higher specific strength and stiffness than those in the aluminum tube. In an attempt to achieve a synergy effect by combining the two members, aluminum/CFRP square tubes were manufactured, which are composed of aluminum tubes wrapped with CFRP outside aluminum square tubes with different fiber orientation angle and thickness of CFRP, and axial collapse tests were performed for the tubes. The crushing behavior and energy absorption capability of the tubes were analyzed and compared with those of the respective aluminum square tubes and CFRP square tubes. Test results showed that the collapse of the aluminum/CFRP square tube complemented unstable brittle failure of the CFRP square tube due to ductile characteristics of the inner aluminum square tube. The collapse modes were categorized into four modes under the influence of the fiber orientation angle and thickness of CFRP. The absorbed energy per unit mass, which is in the light-weight aspect, was higher in the aluminum/CFRP square tube than that in the aluminum square tube or the CFRP square tube alone.