Dynamic analysis of rotor-ball bearings system based on elasto-hydrodynamic lubrication with rubbing-misalignment coupling fault

Dynamic responses of rotor-ball bearing system with elasto-hydrodynamic lubrication (EHL) under rubbing-misalignment coupling faults were studied. Nonlinear dynamic differential equations of rotor-ball bearing system with rubbing-misalignment coupling faults based on EHL and Hertz theory were established. The system equations are numerically integrated to obtain the vibration responses by Runge-Kutta method. Compared with the dynamic characteristics of the rotor system of aero-engine, these were verified through the experimental data. The results show that: (1)Consideration of EHL theory has greatly affected the single rubbing fault system. The onset rotating speed of quasi-periodic to 2-periodic of system with consideration of EHL theory increases more obviously than that without EHL theory, and the rotating speed range of 2-periodic is wider than that without EHL theory. (2) Consideration of EHL theory has greatly affected the rubbing-misalignment coupling fault system. The onset rotating speed of 2-periodic to quasi-periodic increases more obviously than that without EHL theory. (3)By comparing the calculation results with experiment results, it's found that the vibration response at the half and double fundamental frequency of the coupling fault system are weaker than that without EHL theory. The model considering the EHL theory is more accurately to reflect the vibration characteristics of the coupling faults rotor system.