先进高强钢边部成形极限预测方法

Prediction method of edge forming limit for advanced high strength steel

为了对先进高强钢边部成形失效进行准确预测,采取试验和仿真相结合的方式,基于DIC方法开展圆柱凸模扩孔试验,采用Dynaform软件,基于3种断裂失效判据对先进高强钢DP980材料的边部成形极限进行仿真预测,并与试验结果进行比较。结果表明:DIC方法可以准确获得扩孔极限状态,并在线获得扩孔率,可提高扩孔率测量效率和准确性;采用Swift等向强化模型和Hill1948屈服模型预测的扩孔时的主、次应变分布,沿轧制方向与试验结果较为接近,但沿横向仍存在一定差异;进一步比较扩孔率数据,采用最大失效应变判据,扩孔率预测结果与试验更为接近,采用传统的FLC曲线进行预测,与试验结果偏差较大,不能作为边部失效的有效判据。

In order to precisely predict edge forming failure of advanced high strength steels,the method of combining for experiment and simulation was adopted,and the cylindrical punch hole expanding test was conducted based on DIC method. Then,the edge forming limit of advanced high strength steel DP980 material was simulated and predicted by software Dynaform based on three fracture failure criteria,and the simulation results were compared with test results. The results show that the limit state of hole expanding is obtained accurately by DIC method,and the hole expansion rate is gained online to improve the efficiency and accuracy of measurement for the hole expansion ratio greatly. Then,the distributions of major and minor strains for hole expanding predicted by Swift isotropic strengthen model and Hill1948 yield model are close to the test results along the rolling direction,but there are some differences along the transverse direction.Furthermore,the data of hole expansion ratio are compared,the predicted hole expansion ratio is close to the test result by the maximum failure strain criterion,and the predicted result using the traditional FLC curve deviates greatly from the test result,so the traditional FLC curve cannot be used as an effective criterion for edge forming failure.