MODELING OF INSTANTANEOUS ANGULAR SPEED VARIATION OF LARGE CLEARANCE CYLINDRICAL ROLLER BEARING WITH LOCAL DEFECTS IN ROLLING ELEMENT

The instantaneous angular speed (IAS) has been gradually applied to bearing fault identification. The IAS of the fault bearing have periodic disturbance by bearing dynamic modeling and fault simulation experiment in some studies. However, few of them has involved the local characteristics of IAS periodic disturbance, especially the large clearance bearing, which may lead to misdiagnosis. In this paper, a bearing rolling element fault dynamic model is proposed by considering the contact stiffness between the rolling elements and races based on the Hertzian contact theory. Moreover, A fault with 0.25 mm width and 0.2 mm depth was seeded on the roller of the bearing using the laser to verify the validity of simulation results. The results show that the periodic impulse is observed in the IAS, which is mainly due to the sudden change of torque when the defect of the rolling element contacts the raceway, especially in the load area.