A vibration model of a planetary bearing system considering the time-varying wear

Planetary bearings are the key components of the double planetary gear set because of their high loading capacity. As the supporting parts for the planet gears, their behaviors have pronounced influences on the double planetary gear set dynamics. Most previous works only focused on the influence of gear wear on single planetary gear set dynamics. This work creatively proposes a time-varying wear (TVW) model of the planetary bearing for a double planetary gear set, which can be helpful to understand the performance degradation analysis for the double planetary gear set dynamics. The time-varying behavior of relative sliding speeds and contact forces for the planetary bearing contact parts are considered in the TVM model. The bearing and gear excitations are all included in the dynamic model. The TVW model is established by using Archard wear theory. The wear depths of different operating times are analyzed. The influences of the ring wear of planetary bearing on the roller, carrier, planet gear, and cage dynamics are investigated. The results obtained by simulation and experimental methods are evaluated to confirm the accuracy of dynamic model. Moreover, the results show that the ring wear of inner planetary bearing is more severe compared to that of the outer planetary and the outer ring wear is more significant than that of the inner ring.