中文摘要：

基于有限元计算研究了低应力三轴度下,三维孔洞体胞模型的应力应变分布规律和变化趋势,分析了孔洞和基体体积的变化规律,指出用孔洞体积分数表征材料损伤的理论在低应力三轴度下的应用存在局限性。引入断裂应变作为单元失效判据,通过比较单轴拉伸试验和模拟结果,验证了其在材料失效模拟中的可靠性。最后将断裂应变应用到有限元模拟中获得不同应力三轴度下基体失效时的临界等效塑性应变,以临界等效塑性应变为表征参量研究孔洞变形规律和材料的失效行为。

英文摘要：

Based on finite element simulation,a 3D cell model subjected to low stress triaxiality,with a spherical void located in center was developed. The distribution rule of stress and strain was investigated,as well as the developing trend of volume of void and matrix. The analysis indicated that there are some limitations of the theories which regarded void volume fraction as damage parameter. Further research was carried out to verify the reliability of the fracture strain as element failure parameter by analyzing the results of uniaxial tension simulation and experiment. More investigation was conducted to analyze the void growth and material failure under low stress triaxiality by introducing critical equivalent plastic strain as failure criterion.