Nonlinear frequency modulation component decomposition-based time-frequency domain modal parameter identification method

Abstract

The invention discloses a nonlinear frequency modulation component decomposition-based time-frequency domain modal parameter identification method comprising steps of (1) acquiring a dynamic response signal of a to-be-identified structure and setting sampling time and frequency, (2) building a redundancy Fourier model including the response signal, instantaneous frequency and instantaneous amplitude via Fourier series, (3) extracting instantaneous frequency information of the response signal according to generalized parameterization time-frequency transform, (4) extracting instantaneous amplitude information of the response signal according to a regularized least square method according to the acquired instantaneous frequency information, (5) conducting structure modal parameter identification via a linear least square fitting algorithm based on the instantaneous frequency information and slope information of the instantaneous amplitude logarithm and (6) analyzing errors of an identification result. Signal analysis and modal parameter identification are conducted according to a structure vibration response signal, so simple and easy use can be achieved; modal parameter identification precision for high-compact modal structures can be effectively improved; and strong adaptability and interference resistance capacity can be provided.

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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