Forming limit diagram of aluminum-copper two-layer sheets: numerical simulations and experimental verifications

The aim of this research was to introduce a simulation-based approach for determination of the Forming limit curve (FLC) in two-layer metallic sheets. In this study, the FLC of aluminum-1100/copper-C10100 two-layer sheets were obtained through numerical simulations and experimental investigations. In order to construct the FLC, two different criterions including the acceleration (i.e., the second order of derivatives) of equivalent plastic strain and major strain were applied to obtain the onset of necking in the materials. Based on these methods, the localized necking would be started when the acceleration of the equivalent plastic strain or the major strain got its maximum value. To verify the numerical predictions, the experimental works were accomplished on the aluminum-1100/copper-C10100 two-layer sheets and a good agreement between the proposed methods and experimental works was observed.