A dynamic model of defective bearing considering the detailed motion of the roller and the impact between the roller and the cage

To illustrate the vibration characteristics of the defective bearing more precisely, a dynamic model considering the detailed motion of the roller and the impact between the roller and the cage when the roller passes through the defect has been proposed. It overcomes the shortcomings of the previous models in which the roller's and cage's rotational speeds are set as constant values. The proposed model considers the detailed motion of the roller and the impact between the roller and the cage when the roller passes through the bearing defect. The validity and accuracy of the proposed model were verified by an experimental study. The motion characteristics, force characteristics, and vibration characteristics, when the roller passes through the defect, are analyzed. In addition, the vibration signals of the roller passing through two different types of defects are studied. The results show that the roller's rotational speed suddenly increases and the fluctuation amplitude of the revolution speed increases when the roller exits from the large defect. The large defect leads to high-frequency unstable collisions between the roller and the defective raceway. In addition, the slip velocity and the friction force between the roller and the raceway intensify the collision amplitude and generate high-frequency components of the vibration signal. They will also lower the frequency of the roller passing through the outer raceway, especially under high speed and light load conditions. The slipping and the restress between the roller and the defected raceway lead to small variations and big shocks in the vibration acceleration signal, respectively. These phenomena demonstrate the necessity of considering the detailed motion of the roller and the impact between the roller and the cage in the dynamic model.