不同屈服准则与硬化模型对DP780双相高强钢拉延弯曲回弹预测影响规律研究

Influence of Yield Criteria and Hardening Model on Draw-bending Springback Prediction of DP780

随着汽车车身对轻量化、高效节能等要求的提高,先进高强钢因其高比强度、比刚度等性能在汽车工业中应用呈上升趋势。因此,研究先进高强钢的回弹现象,总结其回弹规律,对改善先进高强钢零件的成形精度具有重要意义。目前的研究主要是基于U弯试验研究不同材料模型对回弹的影响规律,而屈服准则和硬化模型对Daw-bending回弹预测的适用性需要进一步研究。基于建立的Draw-bending试验平台,研究圆辊半径与名义张紧力对DP780回弹的影响规律。并利用PAM-STAMP有限元分析软件研究不同硬化模型(Hollomon模型、Y-U模型)和屈服准则(Mises、Hill48、Yld2000)对Draw-bending回弹预测的影响规律。研究表明,在试验方面,增大弯曲半径和张紧力都能减小侧壁卷曲回弹。在有限元仿真回弹预测方面,当采用双精度求解器求解Y-U模型材料参数时,可以提高Draw-bending回弹的预测精度。由于DP780各向异性的特殊性,采用Y-U硬化模型和Mises屈服准则或Yld2000屈服准则可以得到更高的回弹预测精度。对于厚度与截面半径的预测,采用Y-U硬化模型与Yld2000屈服准则可以得到更好的预测精度。

With the improvement of automobile body requirements for lightweight, high efficiency and energy saving, the application of advanced high strength steel in automobile industry is on the rise because of its high specific strength, specific stiffness and other properties. Therefore, it is of great significance to study the springback behavior of advanced high strength steel and summarize its springback law for improving the forming accuracy. Current research is mainly based on U-bending test to study the influence of different material models on springback. The applicability of yield criterion and hardening model to Draw-bending springback prediction needs further study. Based on Drawing-bending test platform, the influence of roll radius and normalized back force on springback of DP780 is studied. Moreover, the influence of different hardening models(Hollomon model, Y-U model) and yield criteria(Mises, Hill48, Yld2000) on Drawing-bending springback prediction is studied by using PAM-STAMP finite element analysis software. The results show that increasing the bending radius and normalized back force can reduce the side wall crimp rebound. For the springback prediction, the accuracy of Draw-bending springback prediction can be improved when the material parameters of Y-U model are solved by a double-precision solver. Because of the particularity of DP780 anisotropy, the combination of Y-U hardening model and Mises yield criterion or Yld2000 yield criterion can obtain higher prediction accuracy. For the prediction of thickness and section radius, the combination of Y-U hardening model and Yld2000 yield criterion can obtain better prediction accuracy.