韧性金属材料渐进断裂的有限元算法研究

ALGORITHM STUDY OF GRADUAL FRACTURE OF DUCTILE METALLIC MATERIAL WITH FINITE ELEMENT METHOD

为解决裂纹稳态扩展的有限元数值仿真,舍弃应力强度因子和J积分理论,考虑韧性金属的弹塑性效应和几何非线性效应,采用基于损伤理论的EWK模型作为断裂判据.有限元计算时将断裂判据以子程序形式嵌入ABAQUS主程序并保持两者之间的实时通信.当材料符合子程序判据时,主程序中以单元弹性模量置"零"来模拟其断裂.求解时使用一种适合控制结构局部失稳的Newton法,并以带椭圆中心孔金属薄板的拉伸断裂为算例.计算结果显示,上述方法实现的断裂效果符合实际物理现象,断裂路径符合一般实验结果.

In order to simulate the gradual expansion of the crack in ductile material, taking into account of the effects of elasticity-plasticity and geometric nonlinearity, the EWK damage model was used as the fracture criterion instead of stress intensity factors or J integral theory. Let this criterion be a subroutine of ABAQUS＇ main program and kept the two in real time communication in finite element algorithm. When some elements met the fracture criterion in subroutine, let the elastic modulus of these elements be “ zero ” in main program to simulate physical fracture. One kind of Newton method which was suitable for localized unstable problems was used in this algorithm. Taking the tensile fracture of a rectangular sheet with a elliptical hole in its center as an example, a numerical result is obtained. The result shows that the effect of the fracture is according to the actual physical phenomena and the path of fracture is consistent with results of general experiments.