DP980高强钢U形弯曲实验与数值模拟

为了评估DP980高强钢材料的成形与回弹特性,通过加载-卸载实验与单向拉伸-压缩循环加载实验,获得了考虑包申格效应的吉田-上森硬化模型参数,并对DP980高强钢的U形弯曲实验进行了研究。实验结果表明,DP980高强钢U形件在凹模圆角处易开裂,在成形过程中需减小压边力并增大凹模圆角。由于材料的回弹量与施加的压边力有关,可通过增大压边力来减小U形件的回弹,但压边力过大又可能导致开裂,因此,需合理选择压边力。同时,对U形件成形后的回弹进行仿真分析,仿真中分别采用等向硬化模型与吉田-上森硬化模型,通过将实验数据与模拟的回弹结果进行对比分析发现,采用吉田-上森硬化模型的仿真结果与实验结果吻合良好,证明了吉田-上森硬化模型模拟回弹的准确度较高,可以应用于回弹仿真中。

Test and numerical simulation of U-shape bending part for DP980 high strength steel

In order to evaluate the forming and springback characteristics of DP980 high strength steel,the parameters of Yoshida-Uemori hardening model which considers Bauschinger effect were obtained through loading-unloading test and uniaxial tension-compression cycle loading test,and the U-shaped bending test of DP980 high strength steel was studied.The results show that the U-shaped part of DP980 high strength steel is easy to crack near the fillet of die,and it is necessary to reduce the blank holder force and increase the fillet of die in the forming process.The springback amount of material is related to the blank holder force,and it can be reduced by increasing the blank holder force.However,excessive blank holder force may lead to crack.Therefore,it is important to choose a reasonable blank holder force.At the same time,the springback of U-shape part after forming was simulated by using the isotropic hardening model and Yoshida-Uemori hardening model.By comparing the experimental data with the springback result of simulation,it is found that the simulation results of Yoshida-Uemori hardening model are in good agreement with the experimental results,which verifies the high accuracy of Yoshida-Uemori hardening model to simulate the springback.So it can be applied in springback simulation.