A new dynamic model for vibration analysis of a ball bearing due to a localized surface defect considering edge topographies

Abstract

When a small initial defect occurs on the races of a ball bearing such as spalls and pits caused by fatigue, the defect will progress around the race in the direction of the ball motion until catastrophic failure happens due to impacts between the ball and the defect edges. Undesirable impulsive excitations can be caused when the orbiting ball strikes the defect edges. The impulse is depended on the shape and sizes of the defect, which can be used to detect and diagnose the defects in bearing systems. To understand characteristics of an impulse caused by a localized surface defect in a ball bearing, a new dynamic model is proposed to investigate the vibration response of a ball bearing due to a localized surface defect on its races, which can consider effects of defect edge topographies. Based on the defect edge topographies and the sizes of the defect, a new contact model for modeling contact relationships between the ball and the defect edges is also developed according to Hertzian elastic contact theory, which can be used to determine changes in the excitations including the time-varying deflection excitation and the time-varying contact stiffness excitation caused by the defect. The proposed model is applied to investigate effects of the defect edge topographies on the contact stiffnesses between the ball and the defect edges, and the vibration response of a ball bearing with a localized surface defect on its races. The results from the proposed model are compared with the available results from the previous models in the literature, which reveals the superiority of the proposed model. It is also shown that numerical results can provide some guidance for the ball bearing defect diagnosis and detection.