Time-Frequency Domain Modal Parameter Identification Method Based on Nonlinear FM Component Decomposition

Abstract

The invention discloses a time-frequency domain modal parameter identification method based on nonlinear frequency modulation component decomposition, comprising the following steps: 1. Obtaining the dynamic response signal of the structure to be identified and setting the sampling time and frequency; 2. Through Fourier The leaf series establishes the redundant Fourier model of the response signal, instantaneous frequency and instantaneous amplitude; 3. Extract the instantaneous frequency information of the response signal through the generalized parameterized time-frequency transformation; 4. According to the obtained instantaneous frequency information, through regularization The instantaneous amplitude information of the response signal is extracted by the least squares method; 5. According to the slope information of the instantaneous frequency and the logarithm of the instantaneous amplitude, the modal parameter identification of the structure is realized by using the linear least squares fitting algorithm; 6. The identification results are analyzed Error Analysis. The invention directly uses the vibration response of the structure for signal analysis and mode parameter identification, is simple and convenient to use, can effectively improve the mode parameter identification accuracy of dense mode structures, and has strong applicability and anti-interference ability.

Description

technical field [0001] The invention relates to a time-frequency domain modal parameter identification method based on nonlinear frequency modulation component decomposition, and belongs to the field of structural dynamic modal parameter identification. Background technique [0002] Modal parameter identification Identifying the modal parameters of the structural system from the measured signals, including modal natural frequency, modal damping ratio, etc., is the basic problem of the linear structural system. The identified modal parameters can be used for model correction in the design phase and damage assessment of structural systems, and many standard design and verification processes in the current industry still mainly rely on linear modal analysis techniques. [0003] Traditional modal parameter identification methods are mainly divided into two categories: time domain method and frequency domain method, among which the method based on Fourier analysis is the most wid...

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Problems solved by technology

[0007] In short, there are two deficiencies in the existing time-frequency domain modal parameter identification methods: 1) the identification effect of the existing methods in the structural modal parameter identification with dense modal features is poor; 2) the current Some methods have serious boundary effects and are sensitive to noise. Noise interference and response attenuation will cause large errors in frequency extraction, resulting in unreliable parameter identification results

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