Torque variations of ball bearings based on dynamic model with geometrical imperfections and operating conditions

A friction torque model of ball bearings with geometrical imperfections is proposed, integrating developed models of friction, raceway waviness, and multi-body dynamics. Torque variations consisting of average and fluctuation values for angular contact ball bearings due to waviness including linear, nonlinear and multi-orders situation are analyzed in time and frequency domains. The influences of waviness amplitude, load and speed are evaluated. Additionally, the correlation between axial displacement and torque fluctuation of ball bearings is discussed, and their spectrum similarity under pure axial load and the relative low-frequency amplitude enhancement of the torque spectrum under combined load are observed. Finally, a torque experiment is carried out on a bearing test apparatus, and the effectiveness of the present model is verified.