DYNAMIC BEHAVIOR OF THE FULL ROTORSTOP RUBBING: NUMERICAL SIMULATION AND EXPERIMENTAL VERIFICATION

Abstract

The dynamic behavior of a rotor rubbing, especially rubbing fully with a motion-limiting stop is investigated by numerical and experimental methods. In the dynamic simulation, the sinuous excitation force with low frequency excites the large whirl of the unbalanced rotor and thus causes the rubbing between the rotor and the stop. The simple Coulomb friction model and the multiple segments linear spring model are used to reveal the nature of the rubbing forces. The torque equation of the rotor is built to extract the rotating speed during partial and full rubbing. The stable partial rubbing motion demonstrates that the stop limits the violent vibration amplitude of the rotor effectively. The rubbing experiments confirm the idea of using the inner type of stop to suppress the violent backward whirl with low frequency. When the amplitude of the excitation force exceeds a certain value, the full rubbing occurs with serious continuous friction. During full rubbing, the center of the rotor moves counter-clockwise and whips in the amplitude exceeding the rotor/stop gap dramatically. Moreover, the whip frequency is much higher than the frequencies of the excitation and the unbalance force. And then the rotor rotation is broken quickly by the stop. The predicted dynamical behavior is verified by the rubbing experiments. The relation between the stop/bearing stiffness ratio and such dynamical behavior as the initiation of the rubbing, the over-limit ratio and the contact-ratio is discussed.