Abstract
This paper describes a new method that detects directly the point where rubbing occurs during operation using data of vibrations. This method is based on the analysis of the nonlinear vibration caused by rubbing. A particular feature of the nonlinear vibration is that the amplitude of higher harmonics in the response becomes large in the vicinity of the point where rubbing occurs. The point where rubbing occurs can, thus, be detected by investigating the distribution of the amplitude of higher harmonics included in the response along the rotor. In the case of a rotor system having an overhanging disk or excited by internal resonance, the distribution of the amplitude occasionally shows another large peak in addition to the peak at the point where rubbing occurs. Even in this case, the presented method can be used to detect the point where rubbing occurs by investigating the eigenvalues and the mode of the rotor system and taking the influence of the overhanging disk into consideration, because the influence of internal resonance on the amplitude of higher harmonics is not great and, furthermore, the influence of the overhanging disk appears only in the vicinity of the overhanging disk.
