Prediction of Forming Limit Curves for 2021 Aluminum Alloy

The forming limit curve (FLC) is a line that is consisted of the major and minor strain pairs for variety kinds of strain paths. It has been widely adopted as a practical criterion in evaluating the formability of different sheet metals. Predicting FLC numerically could avoid the drawbacks of time-consuming and hard-sledding effectively which is shared by the corresponding experimental approach. In this paper, the formability of 2021 aluminum alloy was investigated by conducting forming experiments and corresponding simulations. Firstly, uniaxial tensile tests were conducted to acquire the material properties, as well as to calibrate the hardening model for the 2021 aluminum alloy. Secondly, the numerical model for Nakazima test was established with commercial FE software ABAQUS, and a finite element based criterion was then proposed for predicting the FLC. To verify the validity of predicted FLC, nine sets of tests have been performed, leading to the conclusion that the result of simulation has a better agreement with experimentally determined FLC. Finally, the influence of friction on the strain path was discussed.