U-bending springback prediction of highly anisotropic aluminum alloy sheet by an efficient non-linear combined hardening rule

A non-linear combined hardening constitutive equation was implemented to predict stress after forming process. The model can describe the cyclic strain hardening by the isotropic hardening and the Bauschinger effect by the kinematic hardening. Lemaitre and Chaboche nonlinear kinematic hardening theory was adopted to consider cyclic behavior and the Bauschinger effect. The effects of material hardening rule on Numisheet´93 2-D sheet bending springback was studied. The comparison between simulated results and experimental data shows that the springback prediction by the nonlinear combined hardening is in accord well with each other. The results showed that consideration of the Bauschinger effect is essential to predict the springback on highly anisotropic aluminum alloys.