Effects of Rough Bearing Surface on the Stochastic Dynamics of a Rotor-Bearing System Subject to Random Fluid-Induced Forces

摘要

In this paper, the effects of rough bearing surface on the stochastic responses and the vibration characteristics of a rotor-bearing system subject to random fluid-induced forces are investigated. Based on Stokes theory, the stochastic Reynolds-type equation for the bearing taking into account the influences of rough surfaces is deduced, where roughness heights of bearing surface is considered as an uncertain-but-bounded parameter, which is modeled by a bounded random variable with approximates the Gaussian distribution. The stochastic modeling on uncertainties of bearing surface and fluid-induced forces is then developed. Finally, the dynamic behaviors and response statistics of the stochastic rotor-bearing system are demonstrated by rotor orbit and its mean amplitude of the vibration (MAV for short). The results show that the dynamic responses depend upon the structure type of surface roughness. Generally, the longitudinal roughness tends to decrease the mean size of rotor orbit at critical or sub-critical speed, but it may results in a larger radius of curvature in some position of orbit especially at critical or super-critical speed, while effects of transverse bearing roughness on the mean size of rotor orbit is not significant when frequencies are away from critical speed as compared to the smooth-bearing case.