Abstract: Rub-impact between the rotor and the stator in the rotor-bearing system will cause elastic strain in the rubbing location and thus can produce acoustic emission. Therefore, such acoustic emission can be used to identify and diagnose the rub-impact fault. Analyzing the acoustic emission characteristics of the rub-impact in the rotor-bearing system is emphasized by the experiment. At first, in light rub-impact situation, the acoustic emission and the vibration signal are compared and analyzed to demonstrate the superiority of the acoustic emission based method for the rub-impact identification. Then, the wavelet scalogram is introduced in detail and its characteristics are illustrated through simulation. Finally, the specific experiments are performed. And the wavelet scalogram is used to analyze and discuss the time-frequency features, propagation characteristic and frequency dispersion characteristic of the rub-impact acoustic emission. The results reveal that the rub-impact acoustic emission is the multi-modal elastic wave which mainly includes the flexural wave and extensional wave. It is also indicated that the wavelet scalogram is the strong analysis method for the wave analysis of the modal acoustic emission.

Key words: Acoustic emission, Rotor-bearing system, Rub-impact, Wavelet scalogram