复合型裂纹的扩展路径模拟及疲劳寿命预测

Numerical simulation of crack propagation path and fatigue life prediction for mixed mode cracks

针对二维裂纹稳态扩展,基于位移外推,通过最小二乘法拟合得到应力强度因子数值计算方法;利用最大周向应力准则判断裂纹扩展方向,并得到作为裂纹失稳扩展判据的等效应力强度因子;通过Paris准则得到疲劳寿命预测数值方法。基于ANSYS软件平台,根据上述理论通过APDL编程建立了裂纹扩展路径模拟及疲劳寿命预测模型。该模型可根据裂尖位置进行参数化建模及网格自动划分。将3个典型算例仿真结果与相应解析解或实验结果进行比较,验证了该方法的正确性,为裂纹扩展路径模拟及疲劳寿命预测提供了一种有效的技术手段。

For analyzing the stable crack propagation in 2D solids, the displacement extrapolation technique associated with the least square method is applied to calculate the stress intensity factors. The crack propagation angle and the equivalent stress intensity factors aimed to judge the crack instability propagation are calculated using the maxi- mum circumferential stress criterion. A numerical fatigue life prediction method is then proposed adopting the Paris criterion. Numerical modeling of the crack propagation path and fatigue life prediction is formulated using APDL programming based on the platform of ANSYS. Cracked bodies are parametrically modeled and automatically mesh- ed according to the coordinates of the crack tip. The numerical results of three typical samples agree well with the analytical or experimental results, verifying the accuracy of the proposed algorithms. It provides an effective way to predict the crack growth trajectory and the fatigue life of components.