A new model for bearing-rotor-disk coupling systems with localized failures

Abstract

An accurate mathematical model serves as a fundamental analytical tool for examining the behavior response of mechanical systems. In order to investigate the kinetic behavior of a bearing-rotor-bearing coupled multibody system with localized failures, the mathematical models of flexible rotor and flexible disk based on Timoshenko beam theory and Kirchhoff plate theory are developed in this study, as well as the bearing model considering the time-varying misalignment factor. Then these components are integrated into a novel modeling framework for bearing-rotor-disk systems, which is employed for a detailed analysis of modal responses, operational mechanisms, and the effects of bearing faults and unbalance on system dynamics. The result demonstrates a pronounced coupling relation between rotor structure and rolling bearings, the rotor bending places the bearing in a persistently misaligned operational state, leading to the unavoidable generation of bearing contact angles. The maximum contact angle exceeds 10° when the rotor systems are operated under heavy-load and high-speed and conditions, and the bearing clearance becomes negative, resulting in severe degradation of system stability and nonlinear characteristics. Severe shock is produced due to the bearing raceway defect, and high-frequency fluctuations in bearing contact angle are generated as a result of oscillations in radial displacement of rollers, while the minimum clearance of the bearing is lost by 32.21%, and the contact stiffness is increased by 0.249%. The vortex motions of rotor system will be induced by unbalance faults, node orbit are characterized by circular geometry, and a positive linear correlation is observed between ball-ring contact frequency and rotor working frequency.