This paper reports on the application of nonlinear dynamics and higher-order spectra, with particular regard to the correlation dimension and bispectra in rotating machinery fault identification. The performance of the two methods is evaluated from the view of the practitioners' point. The correlation dimension of nonlinear dynamical system is of value to engineers because it provides an estimation of the number of degrees of freedom that an engineering system possesses. It can provide some intrinsic information of an underlying dynamic system, and can be used to classify different faults intelligently. Therefore, correlation dimension is helpful for an automatic fault detection procedure. Bispectral analysis offers a method for determining the nonlinear coupling and energy exchange between Fourier modes, and explains the origins of spectra peaks at certain values in the frequency spectrum. Such frequency domain information is necessary in order to classify different faults in rotating machinery. Therefore, a combination of correlation dimension and bispectra offer a good description of a nonlinear system. These methods can be complementary to each other in machinery condition monitoring and fault diagnosis field. [References: 30]
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