Dynamic model of rotor system with support loosening and its diagnosis method

Aiming at the specific features of the non-linear rolling bearing-rotor system with pedestal loosening at one support, the dynamics equations of rolling bearing-rotor system were derived using Hertz theory, non-linear dynamics and rotor dynamics, after taking into account the nonlinear condition of looseness. The dynamics equations were numerically integrated for cases with and without looseness, and the vibration signals were obtained for the two cases. The vibration signals were treated with the Fourier transformation and the wavelet transformation respectively. Comparing and analyzing the results, it can be seen that both methods can diagnose the support's loosening fault of the rolling bearing-rotor system effectively, however, the wavelet transformation can diagnose the fault at lower rotating speed, i.e. earlier than the Fourier transformation. The result presented can provide some reference for diagnosing the pedestal loosening fault.