Matching Demodulation Transform With Application to Feature Extraction of Rotor Rub-Impact Fault

Conventional time-frequency analysis (TFA) methods have played an important role in characterizing the TF pattern of nonstationary signals. In this paper, a new TFA algorithm, called matching demodulation transform (MDT), is introduced to extract the highly oscillatory frequency modulation (FM) feature of rotor rub-impact fault. When a rub-impact fault occurs in the rotor system, vibration signals will present the FM feature because of the periodic rub-impact between the stator and the rotor. Through a partial demodulation and stepwise refinement procedure, the highly oscillatory FM feature is represented with satisfactory energy concentration in the time-frequency plane. The validity and practical utility of the MDT is then demonstrated on an experimental rotor system and a practical heavy oil catalytic cracking machine set with a rotor rub-impact fault. The analysis results show that the MDT is powerful in the analysis of FM signals and is an effective tool for the feature extraction of rub-impact faults.