Frequency variation and sensor contribution assessment: Application to an offshore platform in the South China Sea

Liu, Fushun; Li, Huajun; Wang, Weiying; Li, Wei; Wang, Bin

doi:10.1016/j.jsv.2014.10.041

Cited by 9 publications

(2 citation statements)

References 22 publications

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“…The proposed SMF decomposition was then performed on the original signal. As the signal was timeinvariant, the proposed complex exponential decomposition was used directly for the entire period [37] by setting the window length equal to the signal length. As there were three frequency components at each time, the model order was set to 6, and ∆f was set to 0.1.…”

Section: Scheme Of the Proposed Methodsmentioning

confidence: 99%

A new time-frequency analysis method based on single mode function decomposition for offshore wind turbines

et al. 2020

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The Hilbert-Huang transform (HHT) has been widely applied and recognised as a powerful time-frequency analysis method for nonlinear and non-stationary signals in numerous engineering fields. One of its major challenges is that the HHT is frequently subject to mode mixing in the processing of practical signals such as those of offshore wind turbines, as the frequencies of offshore wind turbines are typically close and contaminated by noise. To address this issue, this paper proposes a new time-frequency analysis method based on single mode function (SMF) decomposition to overcome the mode mixing problem in the structural health monitoring (SHM) of offshore wind turbines. In this approach, the structural vibration signal is first decomposed into a set of window components using complex exponential decomposition. A state-space model is introduced in the signal decomposition to improve the numerical stability of the decomposition, and then a novel window-alignment strategy, named energy gridding, is proposed and the signals are constructed in the corresponding gridding. Furthermore, energy recollection is implemented in each gridding, and the reassembling of these components yields an SMF that is comparable to the intrinsic mode function (IMF) of the HHT, but with a significant improvement in terms of mode mixing. Four case studies are conducted to evaluate the performance of the proposed method. The first case attempts to detect three different frequencies in a simulated time-invariant signal. The second case attempts to test a synthesised signal with segmental time-varying frequencies (each segment contains three different frequencies components). The analysis results in these two cases indicate that mode mixing can be reduced by the proposed method. Furthermore, a synthesised signal with slowly varying frequencies is used. These analysis results demonstrate the effective suppression of non-relevant frequency components using SMF decomposition. In the third case, the experimental data from vortex-induced vibration (VIV) experiments sponsored by the Norwegian Deepwater Programme (NDP) are used to evaluate the proposed SMF decomposition for vibration mode identification. In the final case, field data acquired from an offshore wind turbine foundation 1 and offshore wind turbine are analysed. The mode identification results obtained using SMF decomposition are compared with those produced by the HHT. The comparison demonstrates superior performance of the proposed method in identifying the vibration modes of the VIV experimental and field data.

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Section: Scheme Of the Proposed Methodsmentioning

confidence: 99%

A new time-frequency analysis method based on single mode function decomposition for offshore wind turbines

et al. 2020

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“…[7][8][9] The vibration control technology of offshore platforms has received increasing attention. [9][10][11] In recent years, it has been found that when elastic waves. 12 propagate in periodic composites or structures, the elastic waves are internally affected by the periodic structure and cannot propagate in a specific frequency range.…”

Section: Introductionmentioning

confidence: 99%

Study on vibration characteristics of periodic truss structure of offshore platform

Xia

Xiangxi

Fuyu

et al. 2014

Advances in Mechanical Engineering

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Using the band gap properties of the periodic structure, the truss structure of an offshore platform is designed as a one-dimensional periodic conduit structure, and the band gap characteristics are used to realize the vibration control of the truss structure of the offshore platform. The finite element method is used to simulate the vibration characteristics of the periodic conduit, and the influence of the structural parameters (length and wall thickness) of the periodic conduit on the vibration band gap of the periodic conduit is analysed. The frequency response characteristics of the periodic truss structure of an ocean platform are calculated and compared with those of a traditional truss structure. The results show that the periodic truss exhibits better suppression of vibration transmission than the traditional truss, especially for the vibration in the band gap, which is greatly attenuated. This study shows that the periodic structure has broad application prospects in vibration isolation design of truss structures for offshore platforms. The research provides a new technical approach for vibration control of truss structures on offshore platforms.

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Mode shape identification using residues of measured offshore structure data

Wang

Liu

2017

J. Ocean Univ. China

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Frequency variation and sensor contribution assessment: Application to an offshore platform in the South China Sea

Cited by 9 publications

References 22 publications

A new time-frequency analysis method based on single mode function decomposition for offshore wind turbines

A new time-frequency analysis method based on single mode function decomposition for offshore wind turbines

Study on vibration characteristics of periodic truss structure of offshore platform

Mode shape identification using residues of measured offshore structure data

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