Study on energy absorption performance of variable thickness CFRP/aluminum hybrid square tubes under axial loading

Abstract Variable thickness hybrid square (VTHS) tubes which had variable thickness of CFRP to achieve the variation of axial crushing performance are proposed. To study the crushing characteristics and relative advantages of the VTHS, pure aluminum tube, uniform hybrid square tube and VTHS were manufactured firstly, and their axial crushing tests were conducted. Experimental results showed that, compared with uniform hybrid square tube, VTHS had lower initial peak crushing force. Finite element models were established and verified to explore the effect of parameters of the tubes on axial crushing performance further. Numerical results showed that the crushing force can be controlled by varying the thickness of CFRP. Compared with uniform thickness hybrid square tube, VTHS had an improvement of 24.5% in specific energy absorption and increase was greater for the VTHS with thinner metal. Effects of the mean thickness, thickness difference, and number of segments of CFRP on the energy absorption performance were studied. Finally, a theoretical model to predict the mean crushing force was proposed and its accuracy was verified by tests. Results demonstrate that theory can be used to obtain the mean crushing force of each segment of VTHS accurately.