Abstract
The empirical wavelet transform (EWT) method has shown a broad application prospect in the fault diagnosis of rotating machinery. However, it has the problem that the number of modes needs to be preset, and the spectrum segmentation is unreasonable under strong noise. To this end, this paper proposes a modal decomposition method of adaptively constructing empirical wavelet filter banks, which is named adaptive empirical wavelet filter banks (AEWFMD). Firstly, the spectrum trend line is constructed by calculating the energy mean of the Stockwell Transform spectrum along the frequency slice. Secondly, the proposed optimized fault feature energy ratio (OFCER) is used as the objective function, and the smoothing window of the order-statistic filtering is optimized to obtain the optimal spectral line. Then, taking the position of the minimum point of the optimal spectral line as the boundary, it divides the spectrum scientifically and adaptively constructs the empirical wavelet filter bank to reconstruct the modal components. Finally, the optimal modal component is selected based on the OFCER index, and its normalized envelope spectrum analysis is performed. Simulation and experimental results show that AEWFMD can adaptively determine the segmentation boundary and the number of modes. Compared with EWT, empirical Fourier decomposition (EFD), and Feature Mode decomposition (FMD) methods, AEWFMD performs better in single and compound fault feature extraction, which provides a new path for bearing fault diagnosis in engineering practice.
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