Effects of crack and structural flexibility on planetary gear system fault feature considering ring gear boundary condition

The crack will inevitably aggravate the transmission system vibration. In addition, the structure of planetary gear train is much more complex, and due to the installation conditions and other factors, the boundary conditions of ring gear are also different (including the pin support constraint and outer rim constraint). In view of the deficiencies of the existing research on the planetary gear train crack morphology, which are mostly based on simple assumptions and lack of experimental verification, the crack growth test is carried out and the theoretical crack morphology is verified. Then, the vibration feature is analyzed based on the obtained crack morphology and the established system-level dynamic model of the planetary gear train (composed of housing, carrier, gear and shaft, etc.). The studies reveal that the fault feature is more obvious when the initial crack location is far away from the tooth root. Under the boundary condition of outer rim constraint, the thinner ring gear can decrease the dynamic response and crack impact, but when restraining the pin support, the observed phenomenon is opposite. After considering the housing flexibility, the vibration is reduced, however, the increasing flexibility weakens the crack fault feature of the planetary gear train.

Automated summary

The crack in the planetary gear train will worsen the vibration of the transmission system. The complexity of the gear train structure and the different boundary conditions of the ring gear (including pin support constraint and outer rim constraint) make the existing research on crack morphology inadequate. Through crack growth tests and verification of theoretical crack morphology, the vibration characteristics are analyzed based on the obtained crack morphology and the established system-level dynamic model of the planetary gear train.