Internal Resonance Phenomena of the Jeffcott Rotor. Major Critical Speed and Three Times the Major Critical Speed.

Abstract

The Jeffcott rotor is the most widely used model in the analysis of nonlinear resonances of rotors. This model satisfies a condition of internal resonance. since a forward natural frequency and a backward natural frequency always satisfy the ratio of 1: (-1). Due to this internal resonance relation, some unique phenomena may appear in the resonances. However, in most of the previous studies on nonlinear resonances in the Jeffcott rotor, the authors paid no attention to this internal resonance relation. In the previous report, we clarified the effect of internal resonance at twice the maj or critical speed in the Jeffcott rotor. In this study, we deal those phenomena at the major critical speed and at three times the major critical speed theoretically and experimentally. Especially, the influences of internal resonance on the nonlinear oscillations of the Jeffcott rotor are investigated. The result shows that internal resonance relation must be considered in dealing with nonlinear vibrations of rotating machines by the Jeffcott rotor model.