Internal Resonance of a Cracked Rotor (Major Critical Speed and Critical Speeds in Precritical Range)

Abstract

Internal resonance of cracked rotors is investigated using 2-degreeof-freedom rotor systems. Phenomena at the major critical speed and other subcritical speeds in the precritical speed range are discussed theoretically and experimentally. Phenomena in a lateral oscillation model with internal resonance and in an inclination oscillation model with no internal resonance are compared. In the former model, the two critical speeds of forward and backward whirling modes coincide. The following is clarified. (a)The vibration of the synchronous backward whirling mode changes from a steady-state oscillation to an unstable oscillation due to internal resornance. (b)The superhar-monic oscillations of 2nd and 3rd order of the backward whirling mode and the super-subharmonic oscillation of 3/2-order of the backward whirling mode occur due to internal resornance. © 1995, The Japan Society of Mechanical Engineers. All rights reserved.