Research on Time-Varying Stiffness of Bearing Based on Local Defect and Varying Compliance Coupling

Abstract The stiffness characteristics of bearings are influenced by the variation in their compliance and the contour characteristics of local defects. Local profile functions including the depth and varying circumferential extent of local defect are introduced into the analysis model based on the bearing quasi-static model. The bearing quasi-static analysis model with local defect is established, and the correctness of the analysis model is verified. Firstly, the circumferential extents of bearing raceway defects and the influence of axial preload on the number of loaded balls, load distribution and stiffness of static bearing are investigated. Secondly, the influence of varying compliance on the time-varying stiffness of defect-free ball bearing at different rotational speeds is explored. And finally, the time-varying stiffness of bearing with coupling of local defects and varying compliance is examined. Results show that the load distribution and the time-varying stiffness in the coupling state are not the simple superposition of the two states acting separately; they will interact and influence each other, and jointly change the supporting characteristics of bearing. This study can serve as a basis for the nonlinear dynamic analysis, reliability analysis and fault diagnosis of bearing–rotor systems and the design of bearing parameters.