Dynamic modeling and analysis of rolling bearings with rolling element defect considering time-varying impact force

Abstract

Accurately establishing a dynamic model of rolling bearings is significant for understanding the fault mechanism and analyzing the motion characteristics under different performance states. Since the contact process of rolling element defect is more complicated than that of race defect, the research on its characteristics is usually simplified to a certain extent. However, the excitation of the rolling element defect area is closely related to the rotational speed and the size of the defect, the commonly used displacement form of fault excitation can hardly reflect the mechanical characteristics of the actual rolling element fault. A time-varying displacement excitation function of the rolling elements is used to characterize the change of the contact gap between the rolling elements and the inner and outer races. According to the time-varying displacement excitation function, a time-varying impact force excitation function of the defective rolling element is proposed which comprehensively considers defect sizes and the rotational speeds. A four-degree-of-freedom bearing dynamics model based on Hertz basis theory is correlated with time-varying excitation, and the accuracy of the model is confirmed by comparison with the processed experimental signal. Based on the mechanical model and experimental data, the influence of the rotational speeds and defect sizes on the vibration characteristics of the bearing rolling element fault is analyzed and summarized, which provides theoretical support for investigating the mechanism of the bearing rolling element fault.