中文摘要：

在优选模型参数和简化孔洞形核规律的基础上，采用Gurson—Tvergaard（GT）多孔材料本构模型分析金属韧性断裂过程中的宏观应力与应变响应行为；根据金属成形工艺特点，充分考虑拉伸型和剪切型2种不同韧性断裂机制，提出一个统一的韧性断裂准则形式，并通过实验结果验证其有效性和普适性，进而采用单向拉伸实验确定的材料常数合理地预测了正挤压过程中的韧性断裂现象．

英文摘要：

Gurson-Tvergaard （GT） porous material model with optimized adjustment parameters and a practical void nucleation law were adopted to analyze the macroscopic stress-strain response, and according to the character of the metalforming processes, a unified fracture criterion, corresponding to different mechanisms of ductile fracture, tension-type mode and shear-type mode, was proposed. The experimental results confirm the validity and wide applicability of the newly proposed ductile fracture criteria. Moreover, the material constants obtained through uniaxial tension experimental were used to predict the occurrence of the ductile fracture in forward extrusion process.