Effect of static and dynamic misalignment of rolling bearing on nonlinear vibration characteristics of rotor system

In the research on rolling bearing misalignment, the influence of bearing misalignment on the vibration characteristics of the rotor system is rarely considered, especially for the dynamic bearing misalignment. Based on the limitations of the existing research, a five-degree of freedom (5-DOF) nonlinear force model considering bearing misalignment is proposed firstly. The model comprehensively considers the parallel and angular misalignment, static and dynamic misalignment, inner ring and outer ring misalignment. Secondly, the effects of misalignment on the dynamic contact characteristics of bearing and the vibration characteristics of the rotor system are analyzed. Then, based on the dynamic response, the evaluation indexes of bearing misalignment are given. Finally, the similarities and differences between parallel and angular misalignment, static and dynamic misalignment are compared. The results show that the bearing misalignment increases the resonance speed of the rotor, and the amplitude jumping phenomenon appears in the resonance region, showing the characteristics of hardening-type nonlinearity. In terms of frequency characteristics, dynamic parallel misalignment and dynamic angular misalignment increase the amplitude of frequency components f(r) and 2f(r), respectively. The research can be used as a theoretical basis and valuable reference for fault identification of the rotor-bearing system.