An Improved Analytical Model of a Flexible–Rigid Combined Rolling Bearing with Elastohydrodynamic Lubrication

In industrial applications, the operating state of bearings can directly affect the performance of mechanical equipment. Local defects, flexible raceways and lubrication have a great impact on the vibration characteristics of rolling bearings. However, previous works only considered the bearing as a rigid whole or unlubricated state. In order to solve this problem, a flexible–rigid combined bearing dynamics (FRBD) model considering grease lubrication is proposed in this paper. Both the flexible inner race and flexible outer race of a lubricated rolling bearing and a localized defect are formulated in the presented FRBD model. The influence of flexible–rigid combined and grease lubrication on the time- and frequency-domain responses of a rolling bearing with a local fault is analyzed. Based on the constructed model, the root mean square (RMS) value and maximum (MAX) value of time-domain statistical indicators are used to discuss the characteristic changes in acceleration vibration signals under different fault widths, inner-race speeds, and radial forces. In order to verify the accuracy of the FRBD model, the simulation results are compared with the experimental results. These results have a certain guiding role in fault diagnosis for the predictive maintenance of a rolling bearing.