Rad and forouzan et al. Used XFEM extended finite element method to analyze the propagation path ofroot crack, and then applied Paris Finally, the fatigue life in constant amplitude load test is divided into crack initiation life and crack growth life by acoustic emission technology. According to the obtained data, S-N curve and life prediction formula of two kinds of life are analyzed. Through the analysis of the proportion of the two life in the whole life, it is found that the proportion of the initiation life and the extended life is the same at the high stress level, while the germination life is the main one at the low stress level.
Cura and mura et al. Analyzed the crack propagation behavior of cylindrical gear by XFEM extended finite element method, obtained the influencing factors of crack propagation path, and calculated the stress intensity factors Ki and Kii. The results show that the ratio of Kii to kiII has a certain influence on the crack propagation path. On this basis, the crack propagation path of planetary gear is obtained, and the variation law of crack propagation path under different rim thickness and crack initiation position are studied. Finally, the variation of the crack growth path of the rim of the thin edge gear with different web thickness is studied, and the variation law of the crack growth path is obtained. The results show that the thickness of Web will affect the crack propagation and failure mode of rim.
Olsson E and olander A and others analyzed and studied the carburized gear surface by using the method of finite element simulation analysis and experiment, and obtained the S-N curve of the gear through the test. The critical points of finite life stress cycle and infinite life stress cycle of gear are obtained. It is found that the fatigue life of large gear is higher than that of small gear under the same test load. Then, the relationship between residual stress, plastic deformation and stress field at tooth root is analyzed, and a mathematical model which can describe the effective fatigue stress value of each element is proposed. Finally, the correctness of the mathematical model is verified by comparing with the experimental data.