Abstract
Modal parameters are important parameters for the dynamic response analysis of structures. An output-only modal parameter identification technique based on Hilbert Vibration Decomposition (HVD) is developed herein for structural modal parameter identification to (1) obtain the Free Decay Response (FDR) of a structure through free vibration or ambient vibration tests, (2) decompose the FDR into modal responses using HVD, and (3) calculate the instantaneous frequencies and instantaneous damping ratios of the modal responses to obtain the modal frequencies and modal damping ratios. A series of numerical examples are examined to demonstrate the efficiency and highlight the superiorities of the proposed method relative to the empirical model decomposition-based (EMD-based) method. The robustness of the proposed method to noises is also investigated and proved to be positive effect. The proposed method is proved to be efficient in modal parameter identification for both linear and nonlinear systems, with better frequency resolution, and it can be applied to systems with closely spaced modes and low-energy mode.
Highlights
Modal parameters are important parameters for the dynamic response analysis of structures
Results e Hilbert Vibration Decomposition (HVD) method overcomes some shortcomings of the empirical model decomposition (EMD) method, maintains the ability to decompose multifrequency component signals, and detects the amplitude or frequency transient changes of signals. erefore, HVD performs better than EMD in the decomposition or time-frequency analysis of specific types of signals and the modal parameter identification of certain types of structures
Three numerical examples are used to verify the effectiveness and superiority of the modal parameter identification method. e head and tail results were excluded from the example results due to the certain end effect of the decomposition results of the HVD method. e end effect of HVD can be weakened by means of signal extension
Summary
Modal parameters (including modal frequency and modal damping ratio) are important parameters for the dynamic response analysis of structures. Erefore, parameter identification methods based on free vibration or random vibration tests have attracted increasing attention. Because this kind of method does not need to measure the input, they are often called output-only modal analysis (OMA) methods [1]. Many scholars have proposed and developed modal parameter identification methods based on time-frequency analysis [2], including the more classical methods based on wavelet transform, empirical model decomposition (EMD), and Hilbert transform [3, 4]. Many scholars have studied modal parameter identification based on HHT method, introducing some improved algorithms to improve the performance of the HHT method [5]
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