Effect of bearing wear on linear and nonlinear responses of a rigid rotor supported by journal bearings

Linearized dynamic bearing coefficients are commonly used to determine the vibration response of rotors supported by journal bearings. Journal bearings can, however, behave nonlinearly, particularly in the presence of bearing wear. This work was undertaken to examine the effect of bearing wear severity on the linear and nonlinear responses of a rigid rotor at low, moderately, and highly loaded operating regime. Numerical results showed that the center of the nonlinear orbit coincides with the center of the linear orbit for all three operating regimes in non-worn bearing. However, in worn bearings, the center of the nonlinear orbit shifts away from the center of the linear orbit for all three operating regimes. The nonlinear analysis also showed that super-synchronous vibration response may occur, particularly at highly loaded operating regimes and at the maximum wear depth investigated in this work.