Effect of normal anisotropy on springback

Share of high and advanced high strength steels in automobile is increasing, however, such steels generally have poor formability and high amount of springback. One of the focus areas of research in high strength automotive steel is to increase the normal anisotropy to get better formability. Effect of strength and process parameters on springback has been studied by many researchers but that of anisotropy has not been studied by many. In the present work the effect of anisotropy on springback is predicted using finite element analysis for the benchmark problem of Numisheet-2005 [2005 Numisheet Benchmark 2, Springback prediction of a cross member, Proceedings of the 6th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes, Detroit, USA, August 15–19, 2005]. An analytical model is developed to cross check the trends predicted from the finite element analysis. The effective stress has not been treated as a constant and the radial stress is considered in the present model. Both the models (FE and analytical) predict that higher anisotropy, in general, gives higher springback. Finite element analysis of the problem shows that springback is minimum for an isotropic material.