THE SWING VIBRATION, TRANSVERSE OSCILLATION OF CRACKED ROTOR AND THE INTERMITTENCE CHAOS

This paper studies the non-linear dynamic response of a cracked rotor by taking the swing vibration of disc into consideration. The results show that if a small crack appears, the frequency of transverse oscillation is synchronous with rotating speed ratio (Ω), and the frequency of swing vibration is N Ω (N=1,2,…). As the crack increases, the response becomes chaotic in some range of Ω. The deeper the crack is, the wider the chaotic range of Ω is. Routes to chaos include intermittence to chaos and quasi-period to chaos. When the crack is fairly deep, some new resonance regions develop. In these regions, the response becomes infinity rapidly. The appearance of intermittence chaos is induced by the frequent frustration of stable oscillation, which is resulted from the continuous increase of swing amplitude. Unbalance parameter U is effective in suppressing chaos. Crack angle β cannot affect the essence of response, but can influence the amplitude of synchronous response.