Nonlinear vibration characteristics of rolling bearing considering flexible cage fracture

Rolling bearing is one of the critical parts of the transmission system and has a high demand for operating conditions. Suitable operating conditions can ensure that the rolling bearing has a higher rotation accuracy, which significantly impacts the performance of the transmission system. However, under some unsuitable operating conditions, the rolling bearing in the transmission system is faced with failure and other problems. Cage failure is one of the most common bearing failures. In particular, the cage fracture analysis is the most difficult among rolling bearing failures. In order to research its nonlinear vibration characteristics under cage fracture, a nonlinear model of the rolling bearing (4Nb+4 degrees of freedom) considering cage fracture is established. The contact between bearing rings and the rollers, the circumferential interaction between the flexible cage and the rollers, and the interaction between the rollers under the cage fracture fault are considered. Subsequently, the nonlinear characteristics under cage fracture are analyzed. The nonlinear collision forces of roller and cage under cage fracture and different cage clearances are compared. The results show that the collision force between rollers and the cage is greater when fractured than when the cage is healthy. Under multiple cage fractures (the roller number is odd), more prominent frequency doubling phenomena may occur as the number of fractures increases. More shocks are reflected in the relative angular displacement and waveform. Under multiple cage fractures (the roller number is even), the number and interval of fractures can be determined through the waveform and envelope spectrum. The research in this paper can help the health monitoring and fault diagnosis of bearing cages.