Maritime work structure weak nonlinear signal decomposition method

Abstract

The invention relates to a maritime work structure weak nonlinear signal decomposition method, which comprises the steps of determining an original dynamic response of a maritime work structure to be measured, performing FFT conversion on the original dynamic response, and performing equal-interval sliding segmentation on a full-band frequency spectrum; sequentially performing IFFT (Inverse Fast Fourier Transform) on each segmented sub-band to obtain an original dynamic response sub-signal corresponding to each sub-band; decomposing and reconstructing an original dynamic response sub-signal corresponding to each sub-band based on the Prony sequence; comparing the relative residual error between the original dynamic response sub-signal corresponding to each sub-band and the reconstructed dynamic response sub-signal, and judging the decomposition precision of the original dynamic response sub-signal corresponding to each sub-band; reconstructing the full-band dynamic response signal, and judging the overall decomposition precision of the full-band original dynamic response signal. According to the method, high-precision decomposition of the nonlinear signals of the maritime work structure can be efficiently achieved, and a basis is provided for modal parameter identification, time-frequency analysis, noise elimination and other applications of the nonlinear signals.

Description

technical field [0001] The invention belongs to the technical field of dynamic design of marine structures, and in particular relates to a weak nonlinear signal decomposition method of marine structures. Background technique [0002] In order to ensure the safe operation of offshore wind power structures during their service life, structural design has evolved from a simple strength design stage to a reliability design stage. The dynamic design process of structures is no longer a simple calculation of structural dynamic characteristics, but has gradually developed into a process of dynamic response analysis of the entire structure. Due to the complexity of the marine environment in the actual offshore structure, the complexity of the measured signal is determined. Therefore, the measured signal usually has the characteristics of nonlinearity and non-stationarity. The traditional fast Fourier transform, wavelet transform and empirical mode decomposition are used It is diffi...

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Problems solved by technology

However, the frequency band division results of this method and its improved method based on it are susceptible to interference from spectrum leakage and noise pollution, and there is a problem that the various modes of the signal cannot be accurately separated.

[0004] Empirical mode decomposition is based on decomposing signals one by one from high to low frequency. However, due to the influence of the complex environment in which the actual offshore structure is located, modal aliasing and end-point effects usually occur, resulting in poor decomposition effects, and even break down problem

Although the variational empirical mode decomposition proposed on the basis of empirical mode decomposition overcomes the problems of mode mixing and other problems, some parameters required by it are difficult to be determined in advance, which limits its application in actual offshore structural engineering to a certain extent. application on

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