Vibration Force Transmissibility of a Rotor-Stator System with Potential Rub-Impact

This paper investigates the force transmission characteristics between rotor and stator of a rotor dynamic system considering potential rub-impact. The system model comprises a Jeffcott rotor mounted on symmetrically located bearings, and a rigidly supported stator set concentrically with the rotor when the rotor is at static equilibrium position. The centrifugal force generated by the rotor eccentricity during the rotation acts as the vibration excitation source of the system. The nonlinear radial impact force and the tangential rub force in the intermittent contact between the rotor and stator are estimated by adopting a classical rub-impact model. The harmonic balance approximations and the numerical integration method are implemented to solve the governing equations and obtain the steady-state response of the rotor as well as force transmissibility between rotor and stator. The effects of mass unbalance level, contact stiffness, and contact friction coefficient on the rotordynamic behavior and vibration transmission characteristics are examined systematically. The results show that the impact contact has a hardening nonlinearity effect on the steady-state frequency response of the rotor. The increase of the rotor eccentricity can enlarge the vibration response near the resonance peak but may reduce the force transmissibility at certain rotational speed. A lower rub coefficient and a lower contact stiffness may reduce the vibration response as well as force transmission to the stator. These results give a deeper understanding of the effects of rub-impact on the vibration behavior and vibration transmission within rotor-stator system and, therefore, benefit improved designs with better dynamic characteristics.