基于微孔洞长大惯性机制的动态拉伸断裂模型构建

Modeling of Dynamic Tensile Fracture Accounting for Micro-Inertia Effect on Void Growth

采用圆柱体胞模型分析方法,对球形微孔洞在不同加载应变率条件下的动力学响应行为进行了有限元分析,计算结果表明:在微孔洞稳定增长阶段,惯性对微孔洞的快速增长起着关键性作用,其它因素的影响基本可以忽略,微孔洞半径增长率与平均应力的平方根成正比。提出了一个微孔洞增长惯性机制的损伤度演化方程,结合逾渗软化函数描述微孔洞聚集行为,从而构建了一个新的动态拉伸断裂模型,并通过自定义材料模型子程序,把断裂模型嵌入LS-DYNA程序中,对无氧铜平板撞击层裂实验进行了数值模拟研究,计算结果与实验结果的比较令人满意,初步检验了新模型的实用性。

Axisymmetric unit cell model calculations are used to study void growth in a material containing a periodic array of spherical voids under different loading rate rates. Numerical results show that. （1） Micro-inertia is found to have a strong stabilizing effect on void growth process; （2） The growth rate of void increases with the square root of mean stress; （3） Accounting for micro-inertia effect on void growth and percolation stress relaxation during the void-coalescence process, a simple dynamic damage evolution model is proposed for elastic-rigid-perfectly plastic materials~ （4） By using of the proposed model the spall tests on copper under different impact velocities are simulated, and the numerical predictions are in good agreement with the experimental measurements, verifying the model applicability.