基于有限元理论并结合局部应力应变法， 得到了确定尺寸腐蚀坑底部在疲劳载荷作用下产 生非扩展裂纹的萌生寿命值；采用断裂力学模型 通过求解数值积分和非线性方程，得到了微裂纹 扩展到极限尺寸的寿命值和等效裂纹的尺寸；采 用神经网络技术建立了腐蚀坑尺寸与等效裂纹尺 寸之间的非线性映射关系。

The finite element method and local stress and strain method were used to obtain the crack initiation life under fatigue load of each pit.  After getting the life of crack initiation,  the propagation life of initiation crack under pits bottom and the equivalent initial surface crack size were calculated through reverse integration of the Paris fatigue crack growth law and solving the non-linear equation using fracture model. Finally the nonlinear relation was set up between sizes of pits and equivalent initial surface crack by neural network.