Vibration of a rotor with imitation crack: (1st report, Experiment)

An imitation crack which has the same deflection characteristics of cracked rotors and which enables a large crack depth has been thought up, and a vibrational experiment on rotor with an imitation crack, supported horizontally, has been done. Resonance curves and FFT analyses of vibrational waves are measured in the experiment and are shown. As a result, it is found that additional resonances at 1/2, 1/3, 1/4 and 1/5 of the critical speed are caused by the imitation crack. Especially, it has been observed that an unstable vibration occurs at 2/3 of the critical speed in the large crack case. The relation between the stiffness and the rotating angle of the cracked rotors is discussed for the vibrational analysis.