Analytical and experimental investigation on stability of rotor system with spline coupling considering torque, friction coefficient and external damping

The spline coupling is widely used in high-speed rotor systems. As the lack of good understanding of the instability and influence behaviors, the spline induced instability is still not well controlled. From the view of dynamics, torque, friction coefficient and external damping are key factors that influence the stability directly. In this paper, the mechanism and influence law of spline induced instability are investigated. A new model to predict the threshold speed of instability of spline coupled rotor accurately is proposed. A criterion to determine the stability of rotor through judging the relative displacement between splines is derived. Then the effects of torque, friction coefficient and external damping on stability are investigated. Corresponding experiments are carried out to validate the model. The characteristics of instability caused by spline are observed successfully through repeated experiments. Results demonstrate that the mechanism of instability caused by spline is the relative effect of the internal damping from spline coupling and the external damping. This investigation can help with the prediction of instability caused by the spline and the regulation of rotor stability.