The swing vibration and transverse oscillation of a cracked rotor and the intermittence chaos

This paper studies the nonlinear dynamic response of a cracked rotor by taking the swing vibration of disc into consideration. The results show that if small crack appears, the frequency of transverse oscillation is synchronous with rotating speed ratio (Ω), and the frequency of swing vibration is NΩ (N=1,2...). As the crack increases, the response becomes chaos in some range of Ω. The deeper the crack is, the wider the chaos range of Ω is. Routes to chaos include intermittence to chaos and quasi-period to chaos. When crack is fairly deep, there come some new resonance regions. 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 βcan not affect the essence of response but can influence the amplitude of synchronous response.