Study on effect of shaft asymmetry on the dynamic response of the rotor-bearing system

Abstract

In this paper, the dynamic responses of a rotor-bearing system with an asymmetric shaft are studied, focusing on the effect of the shaft asymmetry on the dynamic response of the rotor-bearing system. The asymmetric shaft is modeled considering shear effect based on Timoshenko beam theory. Both one-sided and two-sided cuts are considered in the cross-section of the asymmetric shaft. Various positions and lengths of the cuts along the shaft are also studied. A sliding bearing with cavitation boundary condition is adopted and the nonlinear oil film forces are accounted for in the rotor-bearing system. The eccentricity and the frequency difference of the asymmetric shaft have been investigated by numerical modeling and experimental validation. Their crucial role in determining sub-critical vibration and the dynamic response of the rotor-bearing system is elucidated for the first time. Their effects on sub-critical vibration are investigated for five cases of the asymmetric shafts applied in engineering practice, including different cut types, depths, positions, and lengths. The potential of these two proposed structural parameters for applications in the dynamical analysis of other complex rotor-bearing systems is demonstrated accordingly. The numerical results are in good agreement with the experimental results. This study will contribute to damage identification and health monitoring of such rotor-bearing systems.