Author(s)

Wenyu Ma, Jianwei Yang, Yongqiang Zhang and Ye Yao

Corresponding Author

Wenyu Ma

ABSTRACT

Recently, the high strength steel material has been applied in the automotive manufacture very widely. However, the high strength of the high strength steel would cause great springback, which is serious for the manufacture and fabrication. So how to increase the springback prediction gained much attention. To improve the springback prediction in finite element (FE) model, the Bauschinger effect of the high strength steel should be analyzed. And the Yoshida-Uemori (Y-U) hardening material model is studied for the Bauschinger effect. In this study, the Yoshida-Uemori (Y-U) hardening material model is described and the parameters for this material model were calculated for DP780 according to the cycle tensile-compress tests. The material parameters for Y-U model of DP780 were put into the FE software and the simulations were conducted for U-stamping. The different material parameters were used to evaluate the effect of various material parameters. It can be seen from the results that with the increase of the blank holder force, the springback value of U part decreases in terms of the Bausinger effect. Some model parameters show the significant effect on the springback. And several parameters show the insignificant effect on the springback. The significance order can be measured. And the proper material parameters can be chosen for the simulations.

KEYWORDS

DP steel, springback, bauschinger effect, Yoshida-Uemori equation