Output-only modal analysis using blind source separation techniques

Poncelet, Fabien; Kerschen, Gaëtan; Golinval, Jean‐Claude; Verhelst, Damien

doi:10.1016/j.ymssp.2006.12.005

Cited by 225 publications

(122 citation statements)

References 24 publications

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“…One recent and elegant solution consists of viewing the modal expansion of a set of structural responses as a mixture of modal coordinates -the "source signals" -where the mode shapes fill the columns of a mixing matrix. Then, under quite mild assumptions concerning only the mutual independence of the sources, it is possible to identify all constituents of the mixture up to an arbitrary scaling of the mode shapes [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In turn, standard single-degreeof-freedom techniques can be applied on the separated modal coordinates to identify the global modal parameters.…”

Section: Introductionmentioning

confidence: 99%

Least action criteria for blind separation of structural modes

Antoni

Chauhan

Monnier

et al. 2013

Mechanics & Industry

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-It was recently shown that blind source separation (BSS), as originally developed in the signal processing community, can be used in operational modal analysis to separate the responses of a structure into its individual modal contributions. This, in turn, allows the application of simple single-of-degreefreedom techniques to identify the modal parameters of interest. Several publications have recently attempted to give a posteriori physical interpretations to BSS -as initially developed in telecommunication signal processing -when applied to the field of structural dynamics. This paper proposes to follow the route the other way round. It shows that several separation criteria purposely dedicated to operational modal analysis can be deduced from general physical considerations. Three such examples are introduced, based on very different properties that uniquely characterise a structural mode. The first criterion, coined the "principle of shortest envelope", conjectures that the envelope of a modal response has, among all possible envelopes, the shortest length. That such a principle leads to the governing differential equation of a single-degree-of-freedom oscillator is proved from calculus of variation. The second criterion, coined the "principle of minimum spectral variance", conjectures that the frequency spectrum of a structural mode is maximally concentrated around its central frequency. Finally, the third criterion, coined the "principle of least spectral complexity", states that a structural mode has the lowest possible entropy in the frequency domain. All three criteria can be expressed in terms of a mixing matrix whose columns contain the unknown mode shapes. The recovery of the latter is then trivially achieved by minimising the criteria. Extensive simulations show that the proposed criteria lead to figures of merit very similar to those of the state-of-the-art, while at the same time providing physical insight that other algorithms issued form the signal processing community may dramatically lack. Key words:Operational modal analysis / blind source separation / least action principle / calculus of variation / structural dynamics Résumé -Principes de moindre action pour la séparation aveugle de modes. Des recherches récentes ont montré que certaines méthodes de séparation aveugle de sources, initialement développées pour les signaux de télécommunication, permettent de décomposer les réponses vibratoires d'une structure en ses différentes contributions modales. L'avantage qui s'ensuit pour l'analyse modale opérationnelle est une identification immédiate des paramètres modaux par application des techniques traditionnelles dédiées aux systèmesà un degré de liberté, et ceci sans connaissance des forces excitatrices appliquéesà la structure. L'approche est dite (( aveugle )), car elle ne nécessite aucune connaissance préalable des paramètres structuraux. Plusieurs publications ont récemment tenté de donner a posteriori une interprétation physique aux méthodes de séparation aveugle de sources, lors...

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Section: Introductionmentioning

confidence: 99%

Least action criteria for blind separation of structural modes

Antoni

Chauhan

Monnier

et al. 2013

Mechanics & Industry

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“…The accuracy of the method can be visually assessed by inspecting the modal responses (sources), for instance in the frequency domain. However, many works have shown that the main drawback of SOBI (or BMID) is the need of a number of sensors greater or equal to the number of active modes [2], [9], etc.…”

Section: Discussionmentioning

confidence: 99%

“…Note that BSS techniques may be used for modal identification purposes as reported in [1,2]. In this case, the mixing matrix identifies to the modal matrix of the structure and the identified sources correspond to the normal coordinates.…”

Section: Sobi Algorithmmentioning

confidence: 99%

“…All of these methods have been exploited in many engineering applications owing to their versatility and their simplicity of practical use. For example, BSS techniques showed useful for modal identification from numerical and experimental data [1][2][3][4], for separating sources from traffic-induced building vibrations [5] and for damage detection and condition monitoring [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Damage Detection Using Blind Source Separation Techniques

Hà

Golinval

2011

Sensors, Instrumentation and Special Topics, Volume 6

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Blind source separation (BSS) techniques are applied in many domains since they allow separating a set of signals from their observed mixture without the knowledge (or with very little knowledge) of the source signals or the mixing process. Two particular BSS techniques called Second-Order Blind Identification (SOBI) and Blind Modal Identification (BMID) are considered in this paper for the purpose of structural damage detection or fault diagnosis in mechanical systems. As shown on experimental examples, the BMID method reveals significant advantages. In addition, it is demonstrated that damage detection results may be improved significantly with the help of the block Hankel matrix. The main advantage in this case is that damage detection still remains possible when the number of available sensors is small or even reduced to one.Damage detection is achieved by comparing the subspaces between the reference (healthy) state and a current state through the concept of subspace angle. The efficiency of the methods is illustrated using experimental data.

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“…When the frequency curve jumps from one mode to the other, the corresponding demodulated component also follows this jump. Time [s] Some of these techniques have been already used in the field of structural dynamics as for example POD [4] , SOD [5] and SOBI [6] .…”

Section: Drawbacks Of the Hht And Hvd Methodsmentioning

confidence: 99%

Identification of a Time-Varying Beam Using Hilbert Vibration Decomposition

Bertha

Golinval

2014

Topics in Modal Analysis II, Volume 8

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The present work is concerned by modal identification of time-varying systems. For this purpose, a method based on instantaneous frequency identification and synchronous demodulation is used to extract modal components from recorded signals. The proposed method of iterated sifting process is based on the Hilbert Vibration Decomposition (HVD) technique which is used to extract the instantaneous dominant vibrating component at each iteration. A source separation preprocessing step is introduced to treat multiple degree-of-freedom systems in an optimal way. Sources are used as reference signals to get a single instantaneous frequency of each mode for the demodulation on all the channels. The algorithm is presented and is applied to numerical simulation of a randomly excited time-varying structure for illustration purpose. The investigated structure is made up of a beam on which a non-negligible mass is traveling. The variable location of the mass results in changes in modal parameters.

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Output-only modal analysis using blind source separation techniques

Cited by 225 publications

References 24 publications

Least action criteria for blind separation of structural modes

Least action criteria for blind separation of structural modes

Damage Detection Using Blind Source Separation Techniques

Identification of a Time-Varying Beam Using Hilbert Vibration Decomposition

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