基于不同应变路径的QP980超高强钢板回弹预测

Springback prediction of QP980 ultra high-strength steel plate based on different strain paths

为了更加精准的预测超高强钢冷冲压后零件的回弹大小,提供模具设计及修正理论依据,解决实际生产中的回弹问题,以QP980超高强钢板为研究对象,通过使用自主研发的实验装置完成拉伸压缩循环实验,获取不同预应变下的循环拉伸压缩应力-应变曲线,从而建立QP980超高强钢板在复杂加载模式下的Y-U材料模型。基于不同的材料模型对帽形件进行拉延、成形和翻边等不同冲压应变路径下的回弹数值仿真,并将有限元模拟分析结果与实际回弹值对比。结果表明,在任一成形工艺下,Y-U材料模型都能更加准确的预测高强钢冷冲压回弹,其中屈服准则为Hill48的Y-U材料模型回弹预测最可靠;对于不同冲压应变路径下的Y-U材料模型预测,相较于成形冲压回弹,拉延回弹后的帽形件回弹角θ1预测精度提高了2.1%;相较于翻边冲压回弹,对卷曲半径ρ的预测精度提高了49.6%;而回弹角θ2在成形路径下的预测最贴合,相对误差仅为0.2%。

To predict the springback of ultra high-strength steel parts after cold stamping more accurately,provide the theoretical guidance for mold design and modification,and solve the springback problem in actual production,QP980 ultra high-strength steel plate was taken as the research object and the cyclic tension-compression tests were completed using the self-developed experimental setup to obtain the cyclic tensile and compressive stress-strain curves with different pre-strains,and the Y-U material model of QP980 ultra high-strength steel plate in complex loading mode was established.For hat-shaped parts,numerical simulation of springback under various stamping strain paths such as drawing,forming and flanging based on different material models was completed.The finite element simulation analysis result was compared with the experimental springback values.The results show that under any forming process,the springback of highstrength steel after cold stamping can be predicted by the Y-U material model more accurately,and the springback predicted by the Y-U material model with Hill48 yield criterion is the most reliable.For the prediction of Y-U material model under different stamping strain paths,the prediction accuracy of the springback angleθ1 of hat-shaped parts after drawing is increased by 2.1%compared with the springback of forming stamping;compared with the flanging stamping,the prediction accuracy of curl radiusρof parts formed by drawing is increased by 49.6%;the prediction of the springback angleθ2 under the forming path is the most suitable and the relative error is only 0.2%.