It is shown under which circumstances the normal coordinates of the vibration modes may be interpreted as virtual sources, which renders the. Pdf performance assessment of selected oma techniques for. Antoni new separation techniques for outputonly modal analysis ii structural resonances which originate from the response of the system to transient and random forces, iii and backgroundnoise which usually accountsfor anythingelse that does not. However, engineering structures are most often subject to ambient loads e. One of the most robust and popular frequency domain methods of oma is enhanced frequency domain decomposition efdd. In order to provide an overview of system identification techniques in modal testing, the techniques can be divided into experimental modal analysis ema and oma. Outputonly modal analysis using blind source separation techniques. Blind modal identification applied to outputonly building. If the modes are well separated, this technique will lead to acceptable estimates.
Outputonly modal identification by inoperation modal. Operational modal analysis structural vibration solutions. Abstract this paper deals with the experimentation of traditional modal analysis which is also known as experimental. New separation techniques for outputonly modal analysis. Then blind source separation technique directly decouples or. Proceedings of the 25th international seminar on modal analysis isma, noise and vibration engineering volume 11.
Source separation independent component analysis techniques to wind turbines. Pdf referencebased stochastic subspace identification. Pdf blind modal identification of outputonly structures in. Experimental modal analysis reduces the measurements taken on a. Operational modal analysis oma is a technique of determining dynamic.
This study aims to experimentally validate the blind source separation using ica. An indicator for separation of structural and harmonic model in outputonly modal testing. In modal analysis applications one is not interested in a state space model that ts the data as such, but rather in the modal parameters 20 b. Operational modal analysis using secondorder blind. New separation techniques for outputonly modal analysis core. Introduction blind source separation bss techniques have been recently, a subject of research amongst structural dynamics community for the purpose of modal parameter extraction 14. Physical interpretation of independent component analysis in. This paper discusses such outputonly modal identification method complexity pursuit cp based on blind signal separation. The concept of virtual source is exploited and renders the application of these bss techniques possible. In this paper, we propose a new oma method by borrowing one technique from the statistical. Finally, chapter 5 demonstrates the utility of sobi for outputonly modal analysis in practical applications. This paper proposes to explore the utility of blind source separation. V11 industrial applications of extended outputonly blind. Modal analysis can be performed by two different methods experimental modal analysis ema and operational modal analysis oma.
In the present study, experimental modal analysis is carried out by employing blind source separation techniques and by interpreting the response of a mechanical system as a static mixture of sources. Output only modal analysis scaled mode shape by adding. Antoni new separation techniques for output only modal analysis ii structural resonances which originate from the response of the system to transient and. Estimation of fullfield, fullorder experimental modal model of cable. Machinelearningbased methods for outputonly structural modal. The methodology uses the blind source separation bss techniques which attempt to recover the. Recently, signal processing techniques have been used to perform oma through the estimation of the modal coordinates. Experimental verification of modal identification of a. The proposed method is valid even if the number of active modes exceed the number of sensors. It is shown under which circumstances the normal coordinates of the vibration modes may be interpreted as virtual sources, which renders the application of these bss techniques possible. The force is generated by a modal hammer or a shaker, and measured using a force. In the present paper attention is focused on the secondorder blind identification sobi algorithm and the influence of its analysis parameters on computational time and accuracy of modal parameter estimates.
Outputonly modal analysis using blind source separation. Recently, sca has been applied to operational modal analysis oma, which is also known as outputonly modal identification. The present study carries out outputonly modal analysis using two blind source separation bss techniques, namely independent component analysis and secondorder based identification. Comon, p 1994 independent component analysis, a new concept. The relation between the proper orthogonal modes poms, extracted from the proper orthogonal decomposition pod, also known as principal component analysis, and the normal modes was demonstrated in several studies 6, 7, 8. The recent years have witnessed the fast development of blind source separation bss as a promising signal processing technique, pursuing to. For modal analysis of large structures, it is unpractical and expensive to use artificial excitation e. Operational modal analysis to identify modal parameters in. Health monitoring of civil infrastructures by subspace. Pdf modal identification of output only systems using frequency. Pdf experimental modal analysis using blind source. Several recent works have shown how second order blind source separation sobss techniques, such as second order blind identification sobi 1, 2, can be utilized for the purpose of outputonly modal analysis 37. Operational modal analysis is also called outputonly modal analysis, ambient response analysis, ambient modal analysis, inoperation modal analysis, and natural input modal analysis. Antoni new separation techniques for outputonly modal analysis ii structural resonances which originate from the response of the system to transient and.
Parvathy venugopal department of mechanical engineering. Output only modal analysis of engineering structures. Modal parameters of dynamic systems are estimated just based on the output responses. Pdf blind modal identification of outputonly structures. Outputonly algorithms are needed for modal identification when only structural responses are available. Jan 01, 2004 antoni new separation techniques for outputonly modal analysis table 1 characterisation of the greatest identii ed peaks in the range 0. Jan 07, 2019 independent component analysis is one of the linear transformation methods based the techniques for separating blind sources from the output signals of the system. Modal identification an overview sciencedirect topics. Aug 01, 2007 the present study carries out outputonly modal analysis using two blind source separation bss techniques, namely independent component analysis and secondorder blind identification. Antoni new separation techniques for outputonly modal analysis 229 0 0.
A general framework for blind modal identification bmid was outlined, employing blind source separation bss techniques to solve the modal identification problem. Operational modal analysis is an experimental modal analysis. Outputonly modal anlysis by frequency domain decomposition. Although any real structure has an infinite number of modes. Pdf blind source separation for acoustic and modal. In such cases operational or outputonly modal analysis. It is shown under which circumstances the normal coordinates of the vibration modes may be interpreted as virtual sources, which renders the application of.
Golinval, outputonly modal analysis using blind separation techniques, mechanical systems and signal processing to be submitted. Outputonly modal analysis of linear timeperiodic systems with application to. Brincker r, andersen p and moller n 2000 an indicator for separation of structural and harmonic modes in outputonly modal testing pr. In this paper modal analysis were done experimentally and numerically. Sensors sensors open access mdpi publisher of open. Physical interpretation of independent component analysis. Pdf in this paper a new frequency domain technique is introduced for the modal. Since the noise can be hardly separated from the input, it is usuall.
The present study carries out outputonly modal analysis using two blind source separation bss techniques, namely independent component analysis and. Furthermore, comparisons of the bss based techniques and their limitations for modal analysis have been investigated in references 14,1921. Modal analysis always fits the data to a finiteorder model of discrete masses, springs, and velocityproportional dampers. Innovative methods for outputonly estimation of the modal properties of civil structures are based on blind source separation techniques. Experimental verification of modal identification of a highrise. Blind source separation bss and independent component analysis ica techniques are emerging signal processing techniques that aim at identifying statistically independent sources from a linear mixture of such sources without requiring or with little a priori information about the input source signals.
The data were treated using macec 17, a matlab toolbox for modal analysis in civil engineering, that contains the implementation of the algorithm of section 4. In this paper a new frequency domain technique is introduced for the modal. Application of operational modal analysis and blind. Sparse component analysis sca has been widely used for blind source separation bss for many years. Harmonic removal als preprocessing schritt fur operational.
System identification in structural dynamics using blind. The paper is devoted to the problem of discriminating between operational and natural modes of structures excited by generic inputs. Sep 09, 2007 this paper proposes to explore the potential of blind source separation bss techniques for the estimation of modal parameters, namely the resonant frequencies, vibration modes and damping ratios. Furthermore, this new approach provides a lowcost and noncontact technique. The essential importance of modal identification lies in that the modal information natural frequency, damping ratio, and mode shapes completely captures the dynamic properties of a linear system. Modal analysis is based on an understanding of lumpedparameter systems. New separation techniques for outputonly modal analysis by jerome antoni, luigi garibaldi, stefano marchesiello and menad sidhamed get pdf 1 mb. Poncelet f, kerschen g, golinval jc, verhelst d 2007 outputonly modal analysis using blind source separation techniques.
Experimental modal analysis techniques are divided into two groups. When instrumenting an ema, the input force has to be measured simultaneously with the response. Second order blind source separation techniques sobss and. A very promising procedure in this context is represented by the second order blind identi. Among them, an increasing interest is raising towards the application of blind source separation bss techniques ans et al. This paper proposes another way of doing oma where the postprocessing i. Damage assessment using stiffness matrix decomposition and. The methodology uses the blind source separation bss techniques. This validity of this assumption increases as the modes are better separated and as the damping. The concept of virtual sources, which was introduced in recent publications, allows to consider bss as a simple way of doing outputonly modal.
Golinval, jc 2007 output only modal analysis using blind source separation. The application of system identification to vibrating structures yielded a new research. The paper is devoted to the problem of discriminating between operational and natural. Operational modal analysis oma, also called outputonly modal analysis or inoperation modal analysis, deals with the identification of the modal parameters of a structure using only its output response, i. Structural system identification using ica and sobi is performed on two simulated systems in section 4. Separation of structural modes and harmonic frequencies in. Timedomain output data identification model for pipeline. Request pdf new separation techniques for outputonly modal analysis the paper is devoted to the problem of discriminating between operational and natural modes of structures excited by. Verhelst, output only modal analysis using blind source separation techniques, mechanical systems and signal processing, 21 6 2007 2335. Blind source separation bss techniques allow to recover a set of underlying sources from observations without any knowledge of the mixing process or the sources. Outputonly modal identification by inoperation modal appropriation. Separation bss techniques for outputonly modal analysis purposes. Article information, pdf download for a frequency domain blind identification method for. Pdf referencebased stochastic subspace identification for.
Second order blind source separation techniques sobss. Example of a mixedspectrum composed of a pure tone atf 0. Experimental modal analysis using blind source separation. May 01, 2007 recently, statistical and empirical signal processing techniques have shown promise for experimental modal analysis. Application of operational modal analysis and blind source. Application of operational modal analysis and blind source separation independent component analysis techniques to wind turbines s. Pdf operational modal analysis using secondorder blind. Vital defect information present in the magnetic field data of oil and gas pipelines can be perceived by developing such nonparametric algorithms that can extract modal features and performs structural assessment directly from the recorded signal data. Outputonly modal analysis on operating wind turbines.
Conduct a modal analysis without knowing andor controlling the input excitation. Recently a new nonparametric, outputonly methodology for modal identification has been introduced. Furthermore, algorithms for identification of modal properties are divided according to inputoutput and outputonly excitation methods. Experimental verification of modal identification of a high. Bss techniques were shown useful for modal identification 1, damage detection and condition monitoring 2 from outputonly data. In 4, outputonly data are processed using the empirical mode. Beside the classical time domain and frequency domain techniques, a recent proposal in this field is related to the use of the blind source separation bss techniques for outputonly modal. An alternating least squares als based blind source. Perspectives of secondorder blind identification for.
Output only operational modal analysis oma is a modern branch of experimental modal. The present study carries out outputonly modal analysis using two blind source separation bss techniques, namely independent component analysis and secondorder blind identification. Oma, also referred to as outputonly modal analysis based on mathematical. Department of mechanical engineering saintgits college of engg. One difficulty is that the actual loading conditions cannot generally be measured, and outputonly measurements are available. The fdd is an important tool in operational modal analysis, and it can determine the. Recently, the method has been analytically applied to the identification of mode shapes and modal responses from the output signal of structures. Conduct a modal analysis without knowing andor controlling the.
Operational modal analysis is a new technique in modal oma are discussed briefly in this report. If designer could extract the modal parameters with as high accuracy as with traditional modal analysis without measuring the input force, it will decrease the project cost as well as analysis time. Blind source separation independent component analysis for this purpose is also. Introductionin the last decades, modal analysis has received most attention among other linear system identification techniques. The proposed modal analysis method is illustrated using. A frequency domain blind identification method for operational. Sorry, we are unable to provide the full text but you may find it at the following locations. Mar 07, 2021 phillips aw, allemang rj 1996 single degreeoffreedom modal parameter estimation methods.
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