Blind Source Separation Technique for Operational Modal Analysis in Presence of Harmonic Excitation

Operational modal analysis is an experimental modal analysis approach, which uses vibration data collected when the structure is under operating conditions. Amongst the methods for operational modal analysis, blind source separation–based methods have been shown to be efficient and powerful. The existing blind source separation modal identification methods, however, require the number of sensors to be at least equal to the number of modes in the frequency range of interest to avoid spatial aliasing. In this article, a frequency domain algorithm that overcomes this problem is proposed, which is based on the joint diagonalization of a set of weighted covariance matrices. In the proposed approach, the frequency range of interest is partitioned into several frequency ranges in which the number of active modes in each band is less than the number of sensors. Numerical simulations and an experimental example demonstrate the efficacy of the method.

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VIBRATORY BEHAVIOR OF A DOUBLE PANEL SYSTEM BY THE OPERATIONAL MODAL ANALYSIS

International Journal of Modeling Simulation and Scientific Computing ◽

10.1142/s1793962311000578 ◽

2011 ◽

Vol 02 (04) ◽

pp. 459-479 ◽

Cited By ~ 8

Author(s):

MOHAMED SLIM ABBES ◽

MARIEM MILADI CHAABANE ◽

ALI AKROUT ◽

TAHAR FAKHFAKH ◽

MOHAMED HADDAR

Keyword(s):

Independent Component Analysis ◽

Modal Analysis ◽

Blind Source Separation ◽

Source Separation ◽

Component Analysis ◽

Operational Modal Analysis ◽

Independent Component ◽

Good Argument ◽

Experimental Works

The present study tackles the vibratory behavior of a double panel system by operational modal analysis (OMA) using one of the major techniques of blind source separation (BSS), which is the independent component analysis (ICA). For this purpose, the OMA method and the ICA concept are presented and exploited in order to identify the eigenmodes of a double panel system. Then, results obtained by the OMA technique are presented and compared with those achieved by the modal recombination method. Since a good argument is observed, this approach can be used in conjunction with experimental works.

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Operational modal analysis of a nonlinear oscillation system under a harmonic excitation

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220977550 ◽

2020 ◽

pp. 095440622097755

Author(s):

Xuchu Jiang ◽

Feng Jiang ◽

Biao Zhang

Keyword(s):

Modal Analysis ◽

Nonlinear Oscillation ◽

Normal Modes ◽

Nonlinear Normal Modes ◽

Harmonic Excitation ◽

Forced Response ◽

Operational Modal Analysis ◽

Single Frequency ◽

Modal Parameters ◽

Oscillation System

Operational modal analysis (OMA) is a procedure that allows the modal parameters of a structure to be extracted from the measured response to an unknown excitation generated during operation. Nonlinearity is inevitably and frequently encountered in OMA. The problem: The traditional OMA method based on linear modal theory cannot be applied to a nonlinear oscillation system. The solution: This paper aims to propose a nonlinear OMA method for nonlinear oscillation systems. The new OMA method is based on the following: (1) a self-excitation phenomenon is caused by nonlinear components; (2) the nonlinear normal modes (NNMs) of the system appear under a single-frequency harmonic excitation; and (3) using forced response data, the symbolic regression method (SR) can be used to automatically search for the NNMs of the system, whose modal parameters are implicit in the expression structure expressing each NNM. The simulation result of a three-degree-of-freedom (3-DOF) nonlinear system verifies the correctness of the proposed OMA method. Then, a disc-rod rotor model is considered, and the proposed OMA method’s capability is further evaluated.

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