Dynamic modeling and analysis of planetary gear system for tooth fault diagnosis

This study concentrates on the dynamic modeling and analysis of a planetary gear system with tooth broken faults. Firstly, a systematic calculation method of time-varying mesh stiffness (TVMS) for the planetary gear system is developed. Analytical models are established for both external-external and external-internal gear pairs under both healthy and tooth broken condi-tions. Then, a translational-torsional nonlinear dynamic model is established for a planetary gear system and coupled with the TVMS calculation method, to achieve dynamic simulations with tooth broken faults on the sun, planet and ring gears. The influences of tooth broken faults at different gears and at different damage degrees on the vibration responses are revealed. In addition, 15 condition indicators are chosen to assess their sensitivity to the tooth broken faults in a wide range of operational speed rather than a specific operational speed, in order to provide comprehensive information for evaluating the vibration characteristics and health conditions. Finally, experimental vibration signals from a gear transmission test rig are applied to verify the proposed dynamic model. The modeling method and analysis results here could provide some suggestions for the vibration analysis and fault diagnosis of planetary gear systems, and further provide data basis for the development of fault diagnosis methods.