After the completion of the first propagation, the stress intensity factor is calculated, and the second crack propagation is carried out according to the stress intensity factor, which is a repeated cycle until the fracture is realized. In such a cycle, the stress intensity factor history curve data can be obtained, and the crack growth life curve can be obtained by using the post-processing module of FRANC3D. The calculated results of fatigue crack growth life are shown in the figure.

It can be seen from the figure that with the continuous increase of crack propagation, the life times are also gradually increasing. When the crack propagates to 8.37mm, the whole process of crack propagation is 41 times, fracture occurs, and the final life times is 36891 times. Based on the life prediction of the transmission gear of three ring drive, the length of the expanding crack of 8.37mm is brought into the formula

Comprehensive analysis found that the fatigue life analysis of the internal gear plate is to use joint software analysis, to a large extent to make up for their shortcomings, the analysis results are reasonable and feasible. After the crack appeared, the life decreased sharply to 36891 times, indicating that the crack still has a great influence on the life.