Automatic identification method of modal parameters of offshore platform structure based on IEWT

LENG Jiancheng1, 2, DIAO Kaixin1, PANG Zhe1, FENG Huiyu1

Journal of Vibration and Shock ›› 2024, Vol. 43 ›› Issue (7) : 196-204.

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Journal of Vibration and Shock ›› 2024, Vol. 43 ›› Issue (7) : 196-204.

Automatic identification method of modal parameters of offshore platform structure based on IEWT

  • LENG Jiancheng1, 2, DIAO Kaixin1, PANG Zhe1, FENG Huiyu1
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Abstract

An improved empirical wavelet transform (IEWT) method for structural modal parameter automatic identification is proposed to address the issue of misjudgment of spectral segmentation boundaries in processing low signal-to-noise ratio signals using empirical wavelet transform (EWT). Firstly, the cross power spectrum matrix of the signal is calculated, the singular value decomposition method and the scale space method are used to determine the spectral division boundaries, and the signal is decomposed into several intrinsic mode function components. Then, the random decrement technology and Hilbert transform are combined to realize the automatic identification of modal parameters. The IEWT method was used to identify modal parameters of free vibration response signals and ASCE Benchmark model signals, and compared with the EWT method, AR-EWT and WT method, the result shows that the IEWT method can adaptively determine the spectral segmentation boundaries and has high identification accuracy for modal parameters such as frequency and damping ratio of the structure. Further, this method is applied to identify modal parameters of laboratory offshore platform. It has been proven that this method can be used for modal parameter identification of low-frequency structures in complex noise environments.

Key words

empirical wavelet transform / singular value decomposition / scale space / automatic identification of modal parameters / offshore platform

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LENG Jiancheng1, 2, DIAO Kaixin1, PANG Zhe1, FENG Huiyu1. Automatic identification method of modal parameters of offshore platform structure based on IEWT[J]. Journal of Vibration and Shock, 2024, 43(7): 196-204

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