Effects of Wear on Lubrication Performance and Vibration Signatures of Rotor System Supported by Hydrodynamic Bearings

Wear is one of the most common failures for hydrodynamic bearings. The main purpose of present work is to investigate the effects of wear on lubrication performance and acquire efficient vibration signatures for fault diagnosis. In this paper, a Finite Element Model (FEM) for a two-disk rotor supported on worn hydrodynamic bearings is developed in which the oil film force are evaluated by linear and nonlinear models respectively. Numerical and experimental results indicated that the static and dynamic characteristics of bearing were significantly changed by wear, leading to the drop of system critical speeds due to the deterioration of the constraint status from bearings to the rotor. As the wear depth increases, the onset speed of oil whirl postpones higher while that of oil whip change into lower, and large amplitudes of resonance and oil whip are more likely to be excited meanwhile. More notably, all above vibration signatures of the y direction are more sensitive to wear compared to x direction, which means wear faults can be diagnosed by the difference of vibration characteristics between x and y directions. This research can provide theoretical foundation and engineering guidance of the hydrodynamic bearing wear fault diagnosis.