Operational Modal Analysis Method Based on Power Spectral Density Transmissibility Matrix under Multiple Load Cases

doi:10.3901/JME.2025.09.350

Abstract

Abstract: The operational modal analysis method based on power spectral density transmissibility is highly resistant to noise interference, but its modal parameter identification results are susceptible to interference from harmonic excitation. In view of this, an operational modal parameter identification method based on the power spectral density transmissibility matrix under multiple load cases is established. The method firstly constructs the power spectral density transmissibility matrix (PSDTM) from the measured signals under multiple load cases, then averages and fits all the elements within the Moore-Penrose inverse matrix of the PSDTM to extract the modal frequencies and damping ratios, and obtains the modal vibration shapes based on the left singularity matrix of the PSDTM. Finally, based on the property that PSDTM of the measurement signals under multiple load cases has different ranks at the frequencies corresponding to modes and harmonics, the harmonic modes are eliminated from the identified modal parameters, and then the final modal parameters are obtained. The simulation results of the 5-degree-of-freedom mass-spring-damping system and the operational modal test results of the steel beam verify the validity of the method.

Key words: operational modal analysis, power spectrum density transmissibility, harmonic elimination, modal parameter identification

CLC Number:

TB123

CHU Zhigang, ZHAO Shihao, PAN Feng. Operational Modal Analysis Method Based on Power Spectral Density Transmissibility Matrix under Multiple Load Cases[J]. Journal of Mechanical Engineering, 2025, 61(9): 350-357.

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