Vibration Based Crack Identification of Running Rotor System

In this paper, a method combined with wavelet finite element (WFE) and operational modal analysis (OMA) method is presented to determine the depth and location of crack in a running rotor system. The cracked rotor under operational condition is modeled by WFE to gain precise frequencies. Then, an OMA method combined with correction technique of spectrum analysis, harmonic wavelet filtering, random decrement technique and Hilbert transform method is used to acquire modal parameters of rotor systems under operation condition. By using the measured modal parameters (first three natural frequencies), contours of the specified natural frequency are plotted, and the intersection of the three curves predicts the crack location and size. The experimental results indicate that the proposed method can accurately identify the position and depth of different cracks. The proposed method supplies a tool for online crack identification and condition monitoring for rotor system.