Vibration analysis of rotor systems with bearing clearance using a novel conformal contact model

This paper proposes a novel cylindrical conformal contact model for the large-diameter bearing with small clearance to its housing in aero-engines. Since the clearance between them is usually below one-thousandth of the bearing nominal diameter, Hertz's law is not feasible in this case. The proposed contact model accounts for the surface contact condition and more geometric parameters of the bearing-housing component to obtain more accurate prediction results, which are validated by the finite element method (FEM) results. Based on this novel contact model, the vibration response of a single-disk rotor introduced by Ishida et al. is investigated. Numerical results are in good agreement with experimental results by Ishida et al. Influences of several critical parameters on the vibration responses are also studied. Furthermore, a complex dual-rotor system whose front bearing has a clearance stop between the outer ring and housing is analyzed with the proposed model. Good agreement is shown in the comparison between numerical and experimental results, which shows the feasibility of the proposed model in the contact simulation of large-diameter bearings with a small clearance. The results show that periodic collision between the bearing and housing could lead to self-excited vibrations. A natural frequency component in frequency-domain responses is an important indicator for the occurrence of self-excited vibration. This work provides a reference for the fault diagnosis of practical rotor-bearing systems with bearing clearance.