Feature Extraction of Rotor Systems with Coupling Fault with Crack and Rub-Impact

In practical rotor systems, rotor-stator rub-impact may occur because crack fault causes the increase of vibration amplitude, which is called coupling fault with crack and rub-impact. The vibration signal is non-stationary due to the strong nonlinear characteristics of the coupling fault. In this paper, a rotor test rig was designed to research on nonlinear vibration characteristics of rotor systems with this fault. Some meticulous experiments were performed to simulate crack fault, rub-impact fault and coupling fault of both. The vibration signals were collected in the process of speed up-down running. The rough time-frequency features are extracted by spectrum cascade. For extracting the fault features better, the wavelet time-frequency method is adopted to accurately analyze the local unstable signal. The results show that the fault features can be well extracted by combining the two methods.