Dimensional discussion of traction force vector on ball/raceway interface and study of bearing dynamic behavior

As a crucial component, rolling bearings directly determine the reliability of rotating equipment. However, current dynamic models for predicting the bearing performance either ignore the velocity and stress dispersion at the ball/raceway interface or fail to consider the spin moment generated within the interface. To address this issue, the discrete features of the velocity and stress distribution are considered in this paper, and the micro-element approach is used to construct formulas to obtain the traction vectors in two and three dimensions, respectively. Two bearing dynamic models are further developed for these two types of equations: one model considers the spin moment at the interface owing to unequal contact angles between the ball and the two raceways, while the other model ignores this moment. The reliability of these models is validated by comparison with experimental test results, including cage speed and oil film thickness. The predictions from the quasi-static model are used as theoretical values to compare the ability of the two models to simulate bearing performance under different operating conditions. The results show that the prediction results of the model considering the spin moment are closer to the theoretical values than those of the model ignoring this moment. However, the moment increases the friction at the ball/raceway interface, causing this model to underestimate the extent of bearing sliding.