Analysis of springback simulation based on Bauschinger effect

Strain hardening of mental in one direction reduces the yield stress in the opposite direction, the existence of Bauschinger effect plays a unique role on the accuracy of the sheet metal forming simulation. Especially now extensive use of high strength steels and aluminum alloys, makes springback phenomenon an increasingly important issue, tool manufacturing of Auto-body forming put forward higher requirement for the accuracy of the finite element springback prediction. In order to improve the accuracy of springback prediction it is necessary to study the Bauschinger effect of materials. With a device tension-compression tests of DC06 and DP600 are carried out and the displacement-force relationship in different pretension strain are obtained. U-channel forming tests of DC06 and DP600 is carried out, with the simulation models are built, the magnitude of springback are calculated. The influence of different material models, which include the hardening laws of isotropic hardening, isotropic-kinematic hardening and kinematic hardening, on springback prediction is analyzed by comparing the simulation results, the factor of material model which influence the accuracy of springback prediction are also analyzed. The results show that there are differences between DC06 and DP600 on the size of Bauschinger effect, it is helpful to improve the accuracy of springback calculation when considering the Bauschinger effect, while the sensitivity of material constitutive model on the simulation of small curvature bending forming, limited the springback simulation accuracy.