A comprehensive comparative investigation of frictional force models for dynamics of rotor-bearing systems

Vibrations of a rotor-bearing system (RBS) can be affected by the frictional forces between the components of the inherent bearings. Thus, an in-depth investigation of the influences of the frictional moments of the bearings on the vibrations of the RBS can be helpful for understanding the vibration mechanisms in the rotating machinery. In this study, an improved dynamic model of a RBS considering different frictional force models is presented. A comparative investigation on the influences of the empirical and analytical frictional force models on the vibration characteristics of the RBS is proposed. The empirical frictional force models include Palmgren’s and SKF’s models. The analytical frictional force model considers the rolling friction caused by the radial elastic material hysteresis, slipping friction between the ball and races, viscosity friction caused by the lubricating oil, and contact friction between the ball and cage. The influences of the external load and rotational speed on the vibrations of the RBS are analyzed. The comparative results show that the analytical frictional force model can give a more reasonable method for formulating the effects of the friction forces in the bearings on the vibrations of the RBS. The results also demonstrate that the friction forces in the bearings can significantly affect the vibrations of the RBSs.