An analytical modeling for springback prediction during U-bending process of advanced high-strength steels based on anisotropic nonlinear kinematic hardening model

Abstract

An undesirable factor that affects the dimensional precision and final shape of metallic parts produced in cold forming processes is springback phenomenon. In this paper, an analytical model is introduced to predict springback in U-shaped bending process of DP780 dual-phase steel sheet. It is based on the Hill48 yielding criterion and plane strain condition. In this model, the effect of forming history, the sheet thinning, and the motion of the neutral surface on the springback of U-shaped bending process is taken into account. The anisotropic nonlinear kinematic hardening model (ANK) is used to consider the impact of complex deformation, including stretching, bending and reverse bending. This model is able to investigate the Bauschinger effect, transient behavior and permanent softening. This model is used for the Numisheet2011 benchmark U-shaped bending problem. The effect of the sheet holder force, the coefficient of friction, thickness, material anisotropy, and hardening parameters on the sheet springback is studied. It can be seen that analytical model which presented in this paper has desirable accuracy in the springback prediction, and results are close to experimental data.