A high-precision identification method for steam turbine rotor crack is presented. By providing the first three measured natural frequencies,contours for the specified natural frequency are plotted in the same coordinate,and the intersection of the three curves predicts the crack location and size. The cracked rotor system is modeled using Bspline wavelet on the interval(BSWI)finite element method,and a method based on empirical mode decomposition(EMD)and Laplace wavelet is implemented to improve the identification precision of the first three measured natural frequencies. Compared with the classical nondestructive testing,the presented method shows its effectiveness and reliability. It is feasible to apply this method to the online health monitoring for rotor structure.
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