Fault feature analysis of planetary gear set influenced by cracked gear tooth and pass effect of the planet gears

Based on the loaded tooth contact analysis method, the time-varying mesh stiffness of planetary gear set considering gear crack fault are calculated. The real crack path of gear tooth is simulated based on the fracture mechanics theory. Meanwhile, an improved lumped parameter dynamic model is also established, which can effectively consider the time-varying distance between the planet gear and the transducer mounted on the fixed ring gear. The correctness of the proposed dynamic model is verified with the simulation results in literatures and also the experimental result on a planetary gear test rig. The amplitude modulations phenomenon and the frequency modulation phenomenon can be clearly observed in the simulated results. Using the proposed dynamic model, the fluctuation of the dynamic load sharing factors which considering the crack faults of gears are revealed, the result shows that the ring gear crack fault can rarely affect the dynamic load sharing among the external meshing gear pairs. The analysis in this study can help better understand the internal laws of crack fault for planetary gear set.