Experimental and FE analysis on spring-back of copper/aluminum layers sheet for a L-die bending process

This paper is a conduct of experimental tests to investigate different effective parameters of a UNS C10100 copper/aluminum 1100 spring-back on a two-layer L-die bending sheet through finite element simulations. The parameters are the radius and clearance of die, sheet length, thickness of each layer, different lay ups, and sheet annealing. The paper shows that the spring-back decreases with the reduction of the die clearance and radius, similar to the behavior of single-layer sheet and with the increase of the sheet length. The outcome displays a contradiction with 'no significant effect' in the single-layer sheets, previously published in other papers. Furthermore, the thicknesses of copper and aluminum are important roles to evaluate spring-back; however, there is no certain rule to decrease or increase the spring-back through changing the thickness of each layer. Moreover, this work shows the effects of stacking sequence of aluminum and copper layer on the spring-back, because of the different natural axis in each stacking sequence and also different ultimate strength of each layer. Finally, it is concluded that annealing heat treatment significantly reduces the spring-back, where the intermetallic bond hardness in the interface of Cu/Al layers and spring-back increases with the rise of annealing temperature.