Rotor Torsion Vibrations in the Presence of Continuous Stator Contact

The purpose of this study is to examine the torsion response of a rotor while in continuous contact with a stator for both forward synchronous whirling and backward dry-friction whirling. Experimentally obtained torsional strain data for both of these motions are presented, and the results indicate that the major contributions to the motions occur at the drive speed f_d, twice the drive speed 2f_d and the first torsional natural frequency f_t for forward whirling. During backward whirling, the dominant response occurs at the drive speed f_d and the sum of the whirl speed plus the drive speed at f_w + f_d. A distributed-parameter model in combination with a force-interaction model is used to capture the qualitative aspects of the system response. Simulations with this model reveal that the torsional vibrations are excited by stick-slip forces while undergoing backward whirling. Numerical and experimental results also show that motion at the first torsion natural frequency is the dominant component during forward whirling.