有限元与离散元混合法在裂纹扩展中的应用

Application of combined finite-discrete element method for crack propagation

基于有限元与离散元混合方法研究裂纹扩展模拟问题。对含原生裂纹的结构进行单元离散,用有限元计算单元内部,采用离散元计算单元界面,通过单元连接形式的转变实现连续到非连续的转化;采用平面半弹簧法进行接触判断,通过显示迭代求解运动方程,不断更新单元坐标,实现裂纹扩展的数值模拟。以单裂纹与雁形裂纹在单向位移载荷作用下的扩展为例,对比数模结果与试验结果。结果表明:采用有限元与离散元混合方法可有效模拟单、多裂纹的扩展过程;岩桥为90°的雁形裂纹受对向挤压载荷作用发生翼裂-翼裂贯通。

The process of crack growth was simulated based on the combined finite-discrete element method. The media ex- isting primary cracks was divided by elements. The unit and unit interface were calculated using the finite element and dis- crete element method, respectively. The continuum was converted into discontinuum by transformation of connection types between elements. The contacts were detected using the half-spring method in plane. The motion equation was solved in an explicit iterative scheme. Updating the coordinates of elements, the process of crack propagation was simulated. The simula- tion results of a single crack and en echelon cracks under uniaxial compression were contrasted with experimental results. The results show that the process of crack propagation can be effectively simulated using the combined finite-discrete element method. The en echelon cracks with 90°rock bridge under uniaxial compression were linked by wing cracks.