DP780 双相钢 U 弯回弹预测影响因素研究

Springback is a key factor affecting the dimensional and shape accuracy of cold-formed high-strength steel parts, and the accuracy of high-strength steel springback prediction depends on the accurate material model, it is important to study the influence of the material model on springback prediction accuracy. Based on tension-compression tests with two different strain levels and multi-cycle tension-compression tests, the parameters of the DP780 dual-phase steel Yoshida-Uemori (Y-U) kinematic hardening model were determined. The influence of different hardening models and yield criteria on the U-bending springback prediction was analyzed by LS-DYNA finite element simulation software, and compared with the springback tests. The results show that the Y-U model parameters obtained by different tensile-compression test strategies have great differences, and the Y-U model obtained by the multi-cycle tensile-compression tests has higher prediction accuracy and the U-bending springback error can be controlled within 5%. With the increase of pre-strain, the elastic modulus of DP780 dual-phase steel decreases sharply and gradually becomes flat. The Y-U model considering elastic modulus degradation can improve the prediction accuracy of U-bending springback. Compared with the Swift isotropic hardening model, the Y-U kinematic hardening model combined with the Hill48 yield criterion can obtain higher springback prediction accuracy. The yield criterion has a certain influence on the springback prediction of DP780 dual-phase steel, but its influence on the springback accuracy is significantly lower than that of the hardening model. The research results provide a theoretical basis for the selection of advanced high-strength steel material models and the improvement of springback prediction accuracy.