Self-excited vibrations of a rigid rotor rubbing with the motion-limiting stop

The solutions of the motion governing equations of the rotor-bearing-stop system are analyzed to acquire the behavior of the self-excited vibration. The numerical iteration method is put forward to obtain the periodic solution implying that the rotor whirls forward in the perfect annular orbit and keeps full rubbing with the stop.The dynamics parameters such as the stop-to-bearing stiffness ratio, the friction factor and the damping coefficient determine whether the periodic solution exists. They also affect amplitude and frequency of the periodic solution. The numerical stability analysis on the periodic solution concludes that the periodic solution behaves in an unstable motion state which will develop into the forward dry whip through full rubbing or converge to the decaying natural whirl without rubbing. The evolvement of the unstable full rubbing rests on the initial vibration energy of the rotor. The analysis on existence and stability of periodic solution may explain the observations of initiation of full rubbing observed in experiments.Suggestion on selecting dynamic parameters of the rotor-bearing-stop system is presented in order to avoid the full rubbing which has great or catastrophic harm to the rotating machinery.