Rotor dynamics analysis under uncertainty in lubricant film

Predicting vibrations in rotor dynamics under the impact of uncertainty is still a challenging issue. Research work published in this area is usually focused on the stochastic dynamics of rotor- bearing systems by considering the stiffness and damping coefficients of simplified bearing models as random parameters rather than the original characteristics of the oil film. In this paper, the characterizing parameters of the lubricant film such as the dynamic viscosity are considered as uncertain parameters to investigate their influences on the rotor dynamics response. To this end, the modified Jeffcott rotor model with offset disc is established considering the gyroscopic effect. At the same time, the parameters of the bearing are obtained by solving the dynamic characteristics of oil film. Then, the dynamic response of the rotor is numerically calculated. In order to investigate the influence of the parameters of the lubricant film, the response is modeled as a stochastic process with unknown coefficients by using the generalized polynomial chaos expansion. The coefficients are then determined from some realizations of the response on a set of collocation points. Finally, the accuracy of the method is compared with Monte Carlo Simulation.