Nonlinear vibration of rotor-bearing system considering base-motion and bearing-misalignment

Abstract

The rotor system may be subjected to base motion excitation in addition to unbalanced excitation. Moreover, bearing loads can be simultaneously influenced by the base motion and bearing misalignment caused by assembly errors, potentially causing excessive axial load. To study the vibration characteristics of rotors and the contact characteristics of bearings, a new bearing contact force model of the misaligned angular contact ball bearing is proposed and the proposed bearing model is verified by the measured vibration acceleration responses. Incorporating both base motions and bearing misalignment, a dynamic model of a rotor-bearing system is established. The findings reveal that as the rotating speed of the base increases, the amplitude of the variable compliance vibration frequency of the bearing gradually increases because the base motion intensifies the variable compliance vibration of the bearing and some harmonic frequencies and combined frequencies can be observed. Additionally, base motion significantly amplifies the axial force of the bearing, with the axial load rising by approximately 28 times compared to the system without base motion excitation. Both the base motion and bearing misalignment can change the contact zone for the bearing and base motion can cause the ball and raceway to always maintain contact.