A real-time coupling model of bearing-rotor system based on semi-flexible body element

Abstract

The dynamic response of bearing-rotor systems is crucial to the reliability of rotating machine systems. However, to predict this response, a bearing-rotor system model with rotor flexibility, real-time coupling, and simultaneous solution of the bearing and rotor models is required. To this end, this study proposes a dynamic model of a bearing-rotor system by introducing a semi-flexible body element (SFBE). Drawing on the Timoshenko theory, the rotor flexibility is considered by defining the deflection/force relationship between neighboring SFBEs. By concentrating the SFBE mass at its centroid, the same differential equations of motion as those for bearing assemblies were established, and real-time coupling and simultaneous solutions of the bearing and rotor models were obtained. The dynamic response of the system was determined by solving these equations. The good agreement between the experimental data and simulation results proves the validity of the proposed model. In addition, the effect of eccentric excitation on the dynamic behavior of the bearing-rotor system was investigated. Under eccentric excitation, the ball experienced at least two loaded zones per revolution. As the contact angle increased, the cage stability worsened but subsequently improved.