Springback Investigation of Advanced Path-Dependent Constitutive Models for Sheet Metal Forming

Sheet forming processes generally induce complex loading conditions, including monotonic, reversal, and orthogonal strain paths. Complex work hardening behavior of the sheet metal is revealed when the deformation path involves several steps. In order to investigate the forming conditions that require more advanced hardening models, a specific tension bend under tension (BUT) test configuration has been implemented. The test bench allows to characterize the springback after drawing-like forming processes for different values of tool radius and tension in the sheet. Isotropic and combined isotropic-kinematic hardening models are compared in the framework of refined FE simulations of the experiment. Test configurations are identified where one, the other, or none of the tested models is sufficiently accurate to predict springback. For a few configurations, the need for advanced hardening models is clearly demonstrated.