双线性应变路径下St14-T冷轧薄板成形极限研究

在多轴加载试验机上开展了St14-T冷轧薄板单拉和双拉预变形试验，在此基础上采用CAMSYS自动网络分析仪测量了板料的极限应变，分析了预变形对板料成形极限的影响，试验结果表明：加载应变路径的变化会蚊蝇乱形极限曲线的高低。单拉预应变路径将显著提高正应变比区的成形极限，而对负应变比区的成形极限影响不大。等双拉预应变将明显降低正应变比区的成形极限，对负应变比区的成形极限有所提高，随着等双拉预应变量的增加，整条成形极限曲线将降低。

Forming Limit Analysis of St14-T Cold-rolled Metal Sheet under Double-linear Strain Path

After the uniaxial and equiaxial prestrain test of cold rolled St14 T sheet have been carried out on a multiaxial loading tester,the limit strains of metal sheet are measured by the CAMSYS automatic grid analyzer and the effects of prestrain on forming limit of metal sheet are analyzed.It is shown that the change of loading strain path will affect the forming limit curve.Uniaxial prestrain will obviously improve the forming limit on positive strain ratio zone,while it has little effect on negative strain ratio zone.Equiaxial prestrain will obviously decrease the forming limit on positive strain ratio zone,while it slightly improves the forming limit on negative strain ratio zone.With the increase of equiaxial prestrain,the forming limit of metal sheet will decrease.