中文摘要：

韧性断裂准则作为材料成形极限中的重要指标,对于准确预测金属内部和表面韧性破坏发生的时间和位置、工艺制定和模具设计具有重要的意义。以45钢为材料,采用不同形式的试件进行了拉伸、压缩、剪切、扭转等实验,并利用金属塑性成形模拟专业软件对实验过程进行数值模拟,对工程中广泛使用的11种韧性断裂准则进行分类对比研究。指出Normalized Cockroft ＆ Latham和Brozzo断裂准则比较适用于高应力三轴度成形过程,而Ayada和Rice-Tracy断裂准则更适用于较低应力三轴度成形过程。

英文摘要：

Ductile fracture criterion is a key parameter in material forming limitation.Accuracy predicting surface and internal failure in plastic deformation process affect greatly the technology design of workpiece and die.Tension,compression,torsion and shearing test on 45 steel were utilized for providing the experimental values of the critical values at fracture,and 11 kinds of usually used ductile fracture criterions were selected to simulate the physical experiments and their relative accuracy for predicting and quantifying fracture initiation sites was investigated.The comparing results show that metal forming process under high triaxiality can be estimated successively using both Normalized Cockcroft-latham and the Brozzo ductile fracture criteria,but the Ayada and general Rice-Tracey model work very well for the low triaxiality cases.