Dynamic analysis of a flexible rotor system considering the bearing slip

As an important component of rotating machinery, the rotor system (RSM) has a decisive effect on the system dynamics. Most previous works established the RSM dynamic model without the bearing slip, ball dynamics, and cage dynamics. This work proposes a flexible rotor system (FRSM) dynamic model with the bearing slip, ball dynamics, and cage dynamics. The effect of the bearing slip on the FRSM dynamic is analyzed. The FRSM consists of the rotor, rigid disk, and ball bearings. The rotor is modeled using the Timoshenko beam elements. The dynamic models of the rigid disk and ball bearing are established by using the lumped parameter method. The bearing clearance and installation method effects are considered. An experimental verification is developed to demonstrate the validity of the proposed dynamic model. The results obtained by the proposed model and the previous model without the bearing slip are compared. Moreover, the effects of the rotor rotational speed and rigid disk unbalance eccentric distance on the FRSM dynamics and bearing slip are analyzed. The results shows that rotor rotation frequency (f_s) is not obvious for health FRSM and the amplitudes of f_s and nf_s increase with rotation speed and unbalance eccentric distance, which can provide guidance for fault diagnosis.