References of "Golinval, Jean-Claude"
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See detailFinite Element Model Updating of Plate-like Structures Using Modal Holographic Measurement Field
Simon, Daniel; Golinval, Jean-Claude ULg

Conference given outside the academic context (2002)

Optical measurement techniques are very promising for finite element (F.E.) model updating or error localisation of plate-like structures in the field of structural dynamics. The purpose of this work is ... [more ▼]

Optical measurement techniques are very promising for finite element (F.E.) model updating or error localisation of plate-like structures in the field of structural dynamics. The purpose of this work is to investigate a way to better exploit the high spatial resolution inherent to these techniques in order to correct FE mesh discretisation errors and/or model parameter errors. An important assumption in F.E. model error detection is first to consider the initial mesh as sufficiently fine to well represent the measured (displacement or stress) field. In the case of model updating, the adjustment of the model is performed by minimising the difference between the outputs of the model and the exact solution with respect to design parameters. In the case of FE mesh adaptation, the exact solution has to be estimated whereas in the case of model parameter errors, the reference solution is assumed to be the measured one. The idea developed in this paper is to take advantage of the high spatial resolution offered by optical techniques to calculate successively two error estimators using only measurements. The experimental field is first used for the detection of singular regions corresponding to high gradients. This estimator indicates the regions where a mesh refinement is required. Thus a second estimator is calculated and used for parameter error detection. [less ▲]

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See detailA Robust FRF-based Technique for Model Updating
Pascual, Rodrigo; Razeto, Mario; Golinval, Jean-Claude ULg et al

Conference given outside the academic context (2002)

Frequency Response Functions (FRFs) residues have been widely used in time to update Finite Element models. Major reasons for this is that FRFs are very sensitive to damping properties at resonance peaks ... [more ▼]

Frequency Response Functions (FRFs) residues have been widely used in time to update Finite Element models. Major reasons for this is that FRFs are very sensitive to damping properties at resonance peaks, local modes influence is included and no modal analysis is required. Nevertheless, it is well known that due to their nature, the frequency responses may change its order of magnitude very rapidly for small parameter or frequency changes. This situation may cause serious discontinuities in the topology of the objective function, causing the updating strategy to diverge or to find a local non-physical minimum. A primary tool for the correlation of FRFs is the Frequency Domain Assurance Criterion. This technique introduces the concept of frequency shift between the frequency response shapes of a reference model (the experimental structure) and a perturbed model (an initial non-updated FE model). Such a concept opens the way for using residues at different frequencies. For instance, in reference the residue is composed by point FRFs at anti-resonances. This paper introduces a general FRF-based model-updating technique, which is focused in using stable residues during the interactive optimization procedure. A benchmark case from the Cost F3 action is used to assess the goodness of the method compared to other well known methods. [less ▲]

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See detailModeling of Electro-mechanical coupling in MEMS
Rochus, Véronique ULg; Duysinx, Pierre ULg; Golinval, Jean-Claude ULg

Scientific conference (2002)

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See detailExperimental identification of a non-linear beam, conditionned reverse path method
Kerschen, Gaëtan ULg; Lenaerts, Vincent; Golinval, Jean-Claude ULg

in International Conference on Structural Systems Identification, Kassel, 2001 (2001, September)

A new spectral approach for identification of multi-degree-of-freedom nonlinear systems, called the conditioned reverse path method, has recently been introduced. The key idea of this method is to ... [more ▼]

A new spectral approach for identification of multi-degree-of-freedom nonlinear systems, called the conditioned reverse path method, has recently been introduced. The key idea of this method is to eliminate the distortions caused by the presence of non-linearities in frequency response functions. Conditioned frequency responses are then computed and yield the underlying linear properties without influence of non-linearities. The non-linear coefficient is estimated in a second step. The aim of the paper is twofold. Firstly, the conditioned reverse path method is described in details together with the spectral conditioning techniques. Secondly, the ability of this technique to identify the behaviour of an experimental cantilever beam with a geometrical non-linearity is tested. [less ▲]

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See detailApplication of ARMAV models to identification and damage detection of mechanical and civil engineering structures
Bodeux, Jean-Bernard; Golinval, Jean-Claude ULg

in Smart Materials & Structures (2001), 10(3), 479-489

In this paper, the application of auto-regressive moving average vector models to system identification and damage detection is investigated. These parametric models have already been applied for the ... [more ▼]

In this paper, the application of auto-regressive moving average vector models to system identification and damage detection is investigated. These parametric models have already been applied for the analysis of multiple input-output systems under ambient excitation. Their main advantage consists in the capability of extracting modal parameters from the recorded time signals, without the requirement of excitation measurement. The excitation is supposed to be a stationary Gaussian white noise. The method also allows the estimation of modal parameter uncertainties. On the basis of these uncertainties, a statistically based damage detection scheme is performed and it becomes possible to assess whether changes of modal parameters are caused by, e.g. some damage or simply by estimation inaccuracies. The paper reports first an example of identification and damage detection applied to a simulated system under random excitation. The `Steel-Quake' benchmark proposed in the framework of COST Action F3 `Structural Dynamics' is also analysed. This structure was defined by the Joint Research Centre in Ispra (Italy) to test steel building performance during earthquakes. The proposed method gives an excellent identification of frequencies and mode shapes, while damping ratios are estimated with less accuracy. [less ▲]

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See detailProper orthogonal decomposition for model updating of non-linear mechanical systems
Lenaerts, V.; Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2001), 15(1)

Proper orthogonal decomposition (POD), also known as Karhunen}Loeve (K}L) decomposition, is emerging as a useful experimental tool in dynamics and vibrations. The POD is a means of extracting spatial ... [more ▼]

Proper orthogonal decomposition (POD), also known as Karhunen}Loeve (K}L) decomposition, is emerging as a useful experimental tool in dynamics and vibrations. The POD is a means of extracting spatial information from a set of time-series data available on a domain. The use of (K}L) transform is of great help in non-linear settings where traditional linear techniques such as modal-testing and power-spectrum analyses cannot be applied. These decomposition can be used as an orthogonal basis for e$cient representation of the ensemble. The POM have been interpreted mainly as empirical system modes and the application of POD to measured displacements of a discrete structure with a known mass matrix leads to an estimation of the normal modes. We investigate the use of the proper orthogonal modes of displacements for the identi"cation of parameters of non-linear dynamical structures with an optimisation procedure based on the di!erence between the experimental and simulated POM. A numerical example of a beam with a local non-linear component will illustrate the method. (C) 2001 Academic Press [less ▲]

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See detailTheoretical and experimental identification of a non-linear beam
Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg; Worden, K.

in Journal of Sound & Vibration (2001), 244

The identi"cation of the dynamic characteristics of linear systems is now widely used and interest in non-linear systems has increased. The objective of this paper is to demonstrate the performance of the ... [more ▼]

The identi"cation of the dynamic characteristics of linear systems is now widely used and interest in non-linear systems has increased. The objective of this paper is to demonstrate the performance of the restoring force surface method as far as the identi"cation of non-linear systems is concerned. The vibrations of a clamped beam are investigated for two di!erent kinds of non-linearity. Firstly, the beam shows a non-linear behaviour characterized by a piecewise linear sti!ness and secondly, the non-linearity comes from a bilinear sti!ness. Both numerical and experimental results are presented. (C) 2001 Academic Press [less ▲]

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See detailCOST F3 Structural Dynamics 1997-2001, Presentation and Some Preliminary Results
Golinval, Jean-Claude ULg; Argoul, Pierre

Conference given outside the academic context (2001)

The COST Action F3 “Structural Dynamics” was initiated in 1997 by Professor Jean-Claude Golinval. The main objective of this COST Action is to increase the knowledge required for improving the structural ... [more ▼]

The COST Action F3 “Structural Dynamics” was initiated in 1997 by Professor Jean-Claude Golinval. The main objective of this COST Action is to increase the knowledge required for improving the structural design, the mechanical reliability, and the safety of structures in linear and non-linear dynamics. This research Action is supported by the European Community and is divided into three working groups dealing with the following issues: WG1: “Finite Element Model Updating Methods”; WG2: “Health Monitoring and Damage Detection”; and WG3: “Identification of Non-linear Systems”. This paper presents the objectives of the COST Action F3, the organization of the Action, the members of the management committee, and the scientific program of each working group in more detail. Finally, preliminary results of the COST Action are presented. [less ▲]

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See detailDamage Localisation Using Principal Component Analysis of Distributed Sensor Array
De Boe, Pascal; Golinval, Jean-Claude ULg

Conference given outside the academic context (2001)

The spatial information given by the distributed sensors (e.g., piezoelectric laminates) can be used to forecast structural damage on localised critical spot. It is well known that a localised structural ... [more ▼]

The spatial information given by the distributed sensors (e.g., piezoelectric laminates) can be used to forecast structural damage on localised critical spot. It is well known that a localised structural damage with relative small amplitude does not affect significantly the modal response of the structure, at least at low frequencies. Nevertheless, a local de-lamination or electrode deterioration at the distributed sensor level will show significant changes on the response of the sensor by modifying its apparent electromechanical coupling. Assuming that the number of sensors is greater than the number of involved structural modes, a local structural damage, with relative small amplitude, will only affect a particular distributed sensor without affecting significantly the response of the others. By applying a principal component analysis (PCA) on the sensor time responses, it is possible to see that any change of one particular sensor electromechanical coupling factor will affect the subspace generated by the complete sensor response set. The subspace generated with the damaged structure can then be compared with the subspace of an initial state in order to diagnose damage or not. [less ▲]

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See detailModal Identification of the "Steel-Quake" Structure Using the Data-Driven Stochastic Subspace and ARMAV Methods
BODEUX, Jean-Bernard; Golinval, Jean-Claude ULg

Conference given outside the academic context (2001)

In this paper, two techniques used for modal identification of output-only systems are presented and compared. The first technique is based on an ARMAV model. The method is known as the prediction error ... [more ▼]

In this paper, two techniques used for modal identification of output-only systems are presented and compared. The first technique is based on an ARMAV model. The method is known as the prediction error method (PEM) and requires a non-linear iterative optimisation procedure. The second technique is a stochastic subspace method that estimates the system matrices of a stochastic state space model by a data-driven algorithm and by using numerical techniques such as singular value and QR decompositions. The comparison between both techniques is performed over the “Steel-Quake” benchmark proposed in the framework of COST Action F3 “Structural Dynamics”. The results show that the investigated techniques give good results in term of estimated modal parameters. Especially, it is found that the stochastic subspace technique is much faster than the PEM. [less ▲]

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See detailFinite Element Model Updating of the Garteur SM-AG19 Structure
Thonon, Carole; Golinval, Jean-Claude ULg

Conference given outside the academic context (2001)

This paper reports the procedure followed by the "LTAS-Vibrations et Identification des Structures" research group to generate a low order nite element (F.E.) model of the GARTEUR SM-AG19 structure ... [more ▼]

This paper reports the procedure followed by the "LTAS-Vibrations et Identification des Structures" research group to generate a low order nite element (F.E.) model of the GARTEUR SM-AG19 structure proposed as benchmark in the framework of the European COST Action F3 in structural dynamics. The model is made of beam elements, local inertia and rigid body elements. First, the correlation of the experimental data with the results of the F.E. model shows different levels of discrepancies. To perform local error detection, the size of the measured mode shape vectors is first expanded to the size of the F.E. eigenvectors. Model error localisation is based on the computation of residual strain energy due to errors in the constitutive equations. Updating parameters are then selected using eigenvalue sensitivity and local error analyses. The error localisation procedure is followed by the updating process in order to improve the accuracy of the FE models. The quality of the results is assessed in terms of accuracy of the response prediction to structural modifications. [less ▲]

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See detailIdentification of wire rope isolators using the restoring force surface method
Kerschen, Gaëtan ULg; Lenaerts, Vincent; Golinval, Jean-Claude ULg

in International Conference on Structural Systems Identification, Kassel, 2001 (2001)

The restoring force surface method offers an efficient and reliable identification of non-linear single-degree-of-freedom systems. The method may be extended to multidegree-of-freedom systems but by ... [more ▼]

The restoring force surface method offers an efficient and reliable identification of non-linear single-degree-of-freedom systems. The method may be extended to multidegree-of-freedom systems but by loosing the key advantage of the method which lies in the two-dimensional representation for single-degree-of-freedom systems. An experimental application of the restoring force surface method is considered in the present paper. The structure investigated consists of wire rope isolators mounted between a load mass and a base mass. These helical isolators were found to be characterised by a non-linear behaviour. The results obtained are discussed in details and the advantages and drawbacks of the method are underlined. [less ▲]

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See detailExperimental identification of a non-linear beam, proper othogonal decomposition
Lenaerts, Vincent; Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg

in International Conference on Structural Systems Identification, Kassel, 2001 (2001)

The aim of the paper is twofold

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See detailStrategies for Distributed Piezoelectric Actuator / Sensor Placement by Noise Effect Minimisation and Modal Controllability / Observability
De Boe, Pascal; Simon, Daniel; Golinval, Jean-Claude ULg

Conference given outside the academic context (2000)

This paper investigates the problem of placement procedure for distributed piezoelectric actuators and sensors. Two placement techniques are proposed. The first one is based on the controllability and ... [more ▼]

This paper investigates the problem of placement procedure for distributed piezoelectric actuators and sensors. Two placement techniques are proposed. The first one is based on the controllability and observability Grammians of the system expressed in a modal state-space coordinates. The controllability Grammian is then able to quantify how structural modes are controllable with a set of predefined actuators, while the observability Grammian expresses how much structural modes can be observed from a set of predefined sensors. The second placement technique is based on the selection of the best sensor sets which, for each selected structural modes, have the best signal to noise ratio. The sensor selection is performed by inspecting the Fisher information matrix. The number of sensors is then reduced, in an iterative manner, by eliminating locations that do not contribute significantly to the linear independence of the target modal partitions. [less ▲]

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See detailModal identification in presence of noise using an optimization approach
Thonon, Carole; Golinval, Jean-Claude ULg

Conference given outside the academic context (2000)

This paper deals with the problem of modal parameter identification when the measurements are perturbed by unknown but bounded noise. It is well known that the classical Total Least Square (TLS) solution ... [more ▼]

This paper deals with the problem of modal parameter identification when the measurements are perturbed by unknown but bounded noise. It is well known that the classical Total Least Square (TLS) solution is the most accurate one, but that it is quite sensitive to data perturbations. This feature is a big drawback since it is desirable that the estimated modal parameters should not vary when perturbations on measurements change. An optimisation technique suited to so-called second-order cone programs [2] is proposed and tested. This method sets the identification problem in a MIN-MAX formulation [1] and uses an iterative interior-point primal-dual potential reduction algorithm [3, 4]. The residual error is first maximised over the set of possible perturbations leading thus to a worst-case residual error. Then, it is minimised over the set of identification variables. This procedure guarantees the robustness of the solution in the sense that no perturbation of the considered set could make the residual error bigger. This robustness is obtained to the detriment of an absolute accuracy. A good compromize between robustness and accuracy may be found through the prior resolution of the associate TLS problem. The optimisation program is tested in the case of a clamped-free beam for which closed-form solutions are available. A comparison with the TLS solution is also performed. [less ▲]

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See detailActuator / Sensor Placement and Experimental Modal Analysis on Piezo-Structures
De Boe, Pascal; Golinval, Jean-Claude ULg

Conference given outside the academic context (2000)

Few works have been performed in the field of experimental modal analysis by means of piezoelectric distributed elements. Piezoelectric laminates, initially intended for the monitoring and the control of ... [more ▼]

Few works have been performed in the field of experimental modal analysis by means of piezoelectric distributed elements. Piezoelectric laminates, initially intended for the monitoring and the control of smart structures, could also be dedicated to the experimental modal identification of an open-loop structure. A pole-residue development of the open-loop piezo-structure shows that conventional algorithms and a piezoelectric pseudo-collocated actuator/sensor may be used to estimate the mechanical modal parameters. When an initial mathematical model of the structure is available, the 'best' excitation position is determined by checking the H2 norm of the transfer function of the fully observed system. The same methodology can be applied for the selection of the monitoring locations. In most cases, experimental testing with the selected sensors set, gives acceptable information to identify target modes. These data, coupled with electrical sensing at the piezoelectric element level, can then be used to perform the modal analysis of the piezo-structure. A light clamped-free plate instrumented with piezo-laminates is used to illustrate this experimental approach. [less ▲]

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See detailIdentification of Electromechanical Coupling in Piezo-Structures
De Boe, Pascal; Golinval, Jean-Claude ULg

Conference given outside the academic context (2000)

An identification method based on a structural model updating procedure may be used to improve the knowledge of a piezoelectric tested structure and to determine the coupling coefficients of the ... [more ▼]

An identification method based on a structural model updating procedure may be used to improve the knowledge of a piezoelectric tested structure and to determine the coupling coefficients of the piezoelectric material. This procedure starts with the modal analysis of the open-loop instrumented structure. Let the target modes be a subset of the model modes; a selection of sensor (generally accelerometers) locations is then performed by determining the smaller subset such that the H2 modal norm is as close as possible to the modal norm of the original full set. In most cases, experimental testing with the selected sensor set will give acceptable information to identify target modes. These data, coupled with electrical sensing at the piezoelectric element level, will then be used to perform modal analysis of the piezo-structure. A pole-residue development of the open-loop piezo-structure shows that conventional algorithms may be used to estimate the mechanical modal parameters and the electromechanical coupling matrix. The second step of the procedure is to perform model updating itself. The initial finite element piezoelectric model will be improved stiffness corrections to the global stiffness matrix.. The corrections are split in their mechanical and electromechanical contributions. It is then possible to separate mechanical modelling errors from electromechanical coupling errors. The problem becomes a classical model updating problem which may be solved using well established techniques. This will result not only in a model behaving like the measures, but also in an improved knowledge of the structure behaviour without loosing physical insight. From a numerical point of view, it will be shown that ill-conditioning inherent to the presence of piezoelectric elements presents some difficulties at different steps of the model correction procedure. A clamped-free plate instrumented with piezo-laminates is used to illustrate the model updating approach. The selection of measurement points, using the modal norm criteria, is also presented. Experimental identification data will then be used as inputs for the model correction procedure and the behaviour of the updated model will be compared with the initial model dynamics. [less ▲]

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See detailARMAV Model Technique for System Identification and Damage Detection
BODEUX, Jean-Bernard; Golinval, Jean-Claude ULg

Conference given outside the academic context (2000)

This paper presents an application of ARMAV models in the fields of system identification and damage detection. It is shown how to estimate the modal parameters as well as their uncertainties only on the ... [more ▼]

This paper presents an application of ARMAV models in the fields of system identification and damage detection. It is shown how to estimate the modal parameters as well as their uncertainties only on the basis of output measurements, simply assuming that the excitation is a zero-mean stationary Gaussian white noise. The uncertainties estimation can be used for damage detection. Knowing the modal parameters and their uncertainties, it is possible to assess whether changes of modal parameters are caused by e.g. a damage or simply by estimation inaccuracies. The identification and damage detection method is illustrated on the “Steel-Quake” benchmark proposed in the framework of COST Action F3 “Structural Dynamics”. This structure is used at the Joint Research Centre in Ispra (Italy) to test steel buildings performance during earthquakes. The obtained results indicate the effectiveness of the method in estimating modal characteristics and their uncertainties. [less ▲]

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