The effect of partial rotor-to-stator rubbing is studied both experimentally and analytically. The measured vibration signal
is distorted showing a flattenned portion of the waveform.' Spectral analysis indicated that light rubbing induced vibration is characterized by harmonics at frequencies equal to 1/rev., 2/rev. and 3/rev. Severe rubbing is identified by a spectrum containing subharmonics at 1/3, 2/3 of the rotational frequency. The synchronous component is generally attenuated as a result of rubbing introduced friction. Because of the stiffening effect of rubbing on the rotor, the resonance frequency is further delayed. The results obtained analytically show good qualitative agreement with the experimentally obtained ones.