Vibration Modeling of a Rigid Rotor Supported on the Lubricated Angular Contact Ball Bearings Considering Six Degrees of Freedom and Waviness on Balls and Races

Abstract

Nonlinear vibration analysis of angular contact ball bearings supporting a rigid rotor is presented herein considering the frictional moments (load dependent and load independent components of frictional moments) in the bearings. Six degrees of freedom (DOF) of rigid rotor is considered in the dynamic modeling of the rotor-bearings system. Moreover, waviness on surfaces of inner race, outer race, and ball are considered in the model by representing it as sinusoidal functions with waviness orders of 6, 15, and 25. Two amplitudes of waviness, 0.05 and 0.2 μm, are considered in the investigation looking for the practical aspects. The proposed model is validated with the experimental results by performing the experiments. Moreover, the present model has also been validated with published results of researchers by incorporating needful changes in the DOF in the proposed model. Based on the computed results, it is observed that load dependent frictional moment (LDFM) significantly enhances the amplitudes of vibrations in comparison to load independent frictional moment (LIFM) irrespective to values of waviness amplitude and waviness order. The influence of inner race waviness is relatively more on the vibrations in comparison to waviness of outer race and ball. Moreover, vibrations of system enhance considerably at high amplitude of waviness, increase in the order of waviness, and at elevated operating parameters.