A comprehensive study on the speed-varying stiffness of ball bearing under different load conditions

The stiffness as one of the most important dynamic characteristics of ball bearing, has a great influence on the service performance of bearing and rotor systems. To obtain and analyze the stiffness matrix of ball bearing under arbitrary load conditions, this paper proposed a novel mathematical method for ball bearing modeling and stiffness matrix calculation based on a new initial condition assumption. Based on this, a comprehensive and systematical study to investigate the effect of rotating speed on the stiffness for ball bearing under three typical load conditions has been presented (the pure axial load condition, the pure radial load condition and the combined loads condition). And the influences of bearing basis structure parameters including the internal clearance, ball diameter, inner and outer raceway curvature coefficients on the change rule of the stiffness along with speed of ball bearing under three typical load conditions have been given. The results show that the proposed model has a high versatility, and the change rules of the stiffness along with rotating speed are greatly influenced by the load conditions, bearing structural parameters. Therefore, this paper not only presents a complete algorithm for the modeling and stiffness calculation of ball bearing under arbitrary load conditions, but also provides important guidance for the design of bearing and rotor systems.