Influences of inclined crack defects on vibration characteristics of cylindrical roller bearings

Crack initiation and propagation directions on the raceway surface of cylindrical roller bearings (CRBs) can generate different forms of excitation patterns and affect the vibration level of CRBs. For inclined crack defects on the raceway surface, the direction of a roller passing through the cracked raceway determines the order and amplitude of time-varying displacement (TVD) excitation and time-varying stiffness (TVS) excitation. In this study, two different excitation modes are proposed to simulate the interactions between the roller and the raceway. Then, the excitation modes are integrated into the dynamic model of CRB and used to study the effects of crack inclination and propagation direction on the vibration characteristics of CRBs. The results show that the bearing vibration acceleration caused by excitation mode I is greater than that caused by excitation mode II. The distribution direction of the inclined crack defect on the CRB raceway has a great influence on its vibration level. It can provide useful guidance for early bearing fault detection and diagnosis.