DETERMINATION OF THE RUBBING LOCATION IN A MULTI-DISK ROTOR SYSTEM BY MEANS OF DYNAMIC STIFFNESS IDENTIFICATION

The rotor-to-stator rub is one of the main serious malfunctions that often occur in rotating machinery. Previous research has provided enough tools to judge the existence of this fault. However, it is still a difficult task to detect the rubbing position in a multi-disk rotor system. In this paper, the stiffness is considered as variable and the rub-impact effect is included in this dynamic stiffness. Based on simulation data the least-square method is used to identify the dynamic stiffness at different positions along the rotor. It is found that the dynamic stiffness at the position where the rub-impact occurs is increasing as the rubbing develops and this stiffness at other positions shows very little change. The damping coefficients have similar trends. This method is found to be very effective in detecting the rubbing position.