Parameter identification of a rotor with an open crack

A continuous model is presented for vibration analysis and parameter identification of a static (non-rotating) rotor with an open crack, which is based on two assumptions that the cracked rotor is an Euler–Bernoulli beam with circular cross-section and that the cracked region is modeled as a local flexibility with fracture mechanics methods. Through numerical analysis, the effects of the location and depth of the crack on the changes in the eigenfrequencies and mode shapes of the cracked rotor are investigated, and the ratios of the changes in the first two eigenfrequencies are discussed for rotors with shallow cracks. A crack identification algorithm, which makes use of the deflections of the first mode shape at two symmetric points and the contour diagram of crack location versus crack depth for the first two normalized eigenfrequencies, is proposed to predict the crack location and depth on the rotor, and two illustrative examples demonstrate the validity and availability of the proposed algorithm.