A time-varying comprehensive dynamic model for the rotor system with multiple bearing faults

Abstract

Rotor systems play a vital role in processing machinery, aero engines, and wind turbines. Since moving parts can be worn during operation, the system performance is variable throughout the service period actually, especially for the rotor system with various defects. Unfortunately, the existing models about bearing defects are established neglecting the changes of dynamic behaviors, which may not reflect the practice well. Thus, a model that considers this variation is proposed in this paper. The effects of both distributed and localized defects are modeled under the excitation from the system itself. Based on the Lankarani-Nikaravesh model and experimental observations, we established a time-varying wear model. The influences are considered not only on system dynamic behaviors but also on the geometry topographies of both parts and defects. The proposed model is validated with experimental data and prior researches. Extensive case studies are carried out to investigate the influences of the defects on system performance under an imbalanced excitation. The comparison performances of diverse systems at different times are conducted to illustrate the effects of the wear on systems responses. This model provides a better understanding for the performance evolution of rotor systems during the service period. Additionally, this model is also applicable for system fault diagnosis and health monitoring.