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

A nonlinear frequency modulation, modal parameter technology, applied in complex mathematical operations, electrical digital data processing, special data processing applications, etc., can solve the problems of noise sensitivity, unreliable parameter identification results, poor identification results, etc., to achieve strong application performance and anti-interference ability, improve the modal parameter identification effect, and the effect of simple and convenient use

Active Publication Date: 2017-11-07
SHANGHAI JIAO TONG UNIV
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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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Embodiment 1

[0067] The specific implementation steps of a time-frequency domain modal parameter identification method based on nonlinear frequency modulation component decomposition of the present invention are as follows:

[0068] Step 1, select as image 3 The displacement response time domain waveform of the first degree of freedom shown is the dynamic response signal of the structure to be identified, and the sampling time is set to 4s, and the sampling frequency is 100Hz. pass image 3 The time-domain waveform, frequency spectrum and time-frequency distribution of the displacement response of the first degree of freedom shown in the system can be found that the modal frequencies of the system are located near 3, 13, 32 and 33Hz, which indicates that the third-order modal frequency and The fourth-order modal frequency is the dense mode frequency.

[0069] In step 2, a redundant Fourier model of the response signal, instantaneous frequency and instantaneous amplitude is established t...

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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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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/14
CPCG06F17/141
Inventor 彭志科魏莎
Owner SHANGHAI JIAO TONG UNIV
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