References of "Mechanical Systems & Signal Processing"
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See detailNonlinear generalization of Den Hartog׳s equal-peak method
Habib, Giuseppe ULg; Detroux, Thibaut ULg; Viguié, Régis et al

in Mechanical Systems & Signal Processing (2015), 52-53

This study addresses the mitigation of a nonlinear resonance of a mechanical system. In view of the narrow bandwidth of the classical linear tuned vibration absorber, a nonlinear absorber, termed the ... [more ▼]

This study addresses the mitigation of a nonlinear resonance of a mechanical system. In view of the narrow bandwidth of the classical linear tuned vibration absorber, a nonlinear absorber, termed the nonlinear tuned vibration absorber (NLTVA), is introduced in this paper. An unconventional aspect of the NLTVA is that the mathematical form of its restoring force is tailored according to the nonlinear restoring force of the primary system. The NLTVA parameters are then determined using a nonlinear generalization of Den Hartog׳s equal-peak method. The mitigation of the resonant vibrations of a Duffing oscillator is considered to illustrate the proposed developments. [less ▲]

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See detailSubspace-based identification of a nonlinear spacecraft in the time and frequency domains
Noël, Jean-Philippe ULg; Marchesiello, Stefano; Kerschen, Gaëtan ULg

in Mechanical Systems & Signal Processing (2014), 43(1-2), 217-236

The objective of the present paper is to address the identification of a strongly nonlinear satellite structure. To this end, two nonlinear subspace identification methods formulated in the time and ... [more ▼]

The objective of the present paper is to address the identification of a strongly nonlinear satellite structure. To this end, two nonlinear subspace identification methods formulated in the time and frequency domains are exploited, referred to as the TNSI and FNSI methods, respectively. The modal parameters of the underlying linear structure and the coefficients of the nonlinearities will be estimated by these two approaches based on periodic random measurements. Their respective merits will also be discussed in terms of both accuracy and computational efficiency and the use of stabilisation diagrams in nonlinear system identification will be introduced. The application of interest is the SmallSat spacecraft developed by EADS-Astrium, which possesses an impact-type nonlinear device consisting of eight mechanical stops limiting the motion of an inertia wheel mounted on an elastomeric interface. This application is challenging for several reasons including the non-smooth nature of the nonlinearities, high modal density and high non-proportional damping. [less ▲]

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See detailFrequency-domain subspace identification for nonlinear mechanical systems
Noël, Jean-Philippe ULg; Kerschen, Gaëtan ULg

in Mechanical Systems & Signal Processing (2013), 40

This paper introduces a new frequency-domain subspace-based method for the identification of nonlinear mechanical systems. The technique exploits frequency-domain data and interprets nonlinearities as ... [more ▼]

This paper introduces a new frequency-domain subspace-based method for the identification of nonlinear mechanical systems. The technique exploits frequency-domain data and interprets nonlinearities as feedback forces exciting the underlying linear system. It is first demonstrated using two academic examples, namely a Duffing oscillator and a five-degree-of-freedom system comprising two nonlinearities. The identification of an experimental beam exhibiting geometrically nonlinear behaviour is then addressed. [less ▲]

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See detailDamping identification of lightly damped linear dynamic systems using Common-base Proper Orthogonal Decomposition
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in Mechanical Systems & Signal Processing (2012), 28

This paper presents a new technique to identify the damping of linear systems. It is developed from the Proper Orthogonal Decomposition (POD) of the free response of the system and extended to the ... [more ▼]

This paper presents a new technique to identify the damping of linear systems. It is developed from the Proper Orthogonal Decomposition (POD) of the free response of the system and extended to the recently proposed Common-base POD (CPOD). The present application of CPOD considers simultaneously several free responses of the system to different initial conditions. The eigen-decomposition of the co-variance matrix leads to a unique vector basis which is likely to contain more information about the dynamics of the system than a vector basis obtained by the classic POD technique. The ability of the technique to estimate the mode shapes and the modal damping is demonstrated on a simulated mass-spring-damper system. Two different distributions of masses are considered in order to confront the CPOD analysis to the intrinsic limitation of POD, i.e. that the mode shapes are identified exactly only if the mass matrix is proportional to the identity matrix. It is shown that the identification of the damping is still possible when the modes are not orthonormal. The robustness of the technique is demonstrated in the presence of noise in the responses of the system and through an experimental application with comparison with other identifications techniques. [less ▲]

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See detailDetection and quantification of non-linear structural behavior using principal component analysis
Hot, A.; Kerschen, Gaëtan ULg; Foltete, E. et al

in Mechanical Systems & Signal Processing (2011), 26

The detection of non-linear behavior in structural dynamics is a very important step to the extent that the presence of non-linearities, even local, can affect the global dynamic behavior of a structure ... [more ▼]

The detection of non-linear behavior in structural dynamics is a very important step to the extent that the presence of non-linearities, even local, can affect the global dynamic behavior of a structure. A large number of techniques that enable engineers to detect non-linear behavior can be found in the literature but most of these methods exploit frequency domain data and give better results with a stepped-sine excitation. The goal of this paper is to propose an alternative methodology that is based on the principal component analysis and uses time responses obtained with a random excitation. Two criteria will be used to quantify the difference between two response subspaces, based on the angle between them and the residual error resulting from the projection of one on the other. The concept of limit of linearity and design decision margins is also addressed in this paper. The methodology is demonstrated using an academic simulated system and then using measured data of a simplified solar array system. [less ▲]

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See detailLocalization and quantification of damage in beam-like structures using sensitivities of principal component analysis results
Nguyen, Viet Ha ULg; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2010), 24(6), 1831-1843

Principal component analysis (PCA) is known as an efficient method for dynamic system identification and diagnosis. This paper addresses a damage diagnosis method based on sensitivities of PCA in the ... [more ▼]

Principal component analysis (PCA) is known as an efficient method for dynamic system identification and diagnosis. This paper addresses a damage diagnosis method based on sensitivities of PCA in the frequency domain for linear-form structures. The aim is not only to detect the presence of damage, but also to localize and to evaluate it. The Frequency response functions measured at different locations on the beam are considered as data for the PCA process. Sensitivities of principal components obtained from PCA to beam parameters are computed and inspected according to the location of sensors; their variation from the healthy state to the damaged state indicates damage locations. The damage can be evaluated next providing that a structural model is available; this evaluation is based on a model updating procedure. It is worth noting that the diagnosis process does not require a modal identification achievement. Both numerical and experimental examples are used for better illustration. [less ▲]

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See detailIdentification of multi-degree of freedom non-linear systems using an extended modal space model
Platten, Michael F; Wright, Jan Robert; Dimitriadis, Grigorios ULg et al

in Mechanical Systems & Signal Processing (2009), 23(1), 8-29

The identification of non-linear dynamic systems is an increasingly important area of research, with potential application in many industries. Current non-linear identification methodologies are, in ... [more ▼]

The identification of non-linear dynamic systems is an increasingly important area of research, with potential application in many industries. Current non-linear identification methodologies are, in general, mostly suited to small systems with few degrees of freedom and few non-linearities. In order to develop a practical identification approach for real engineering structures, the capability of such methods must be significantly extended. In this paper, it is shown that such an extension can be achieved using multi-exciter techniques in order to excited specific modes or degrees of freedom of the system under investigation. A novel identification method for large non-linear systems is presented, based on the use of a multi-exciter arrangement using appropriated excitation applied in bursts. This proposed Non-linear Resonant Decay Method is applied to a simulated system with 5 degrees of freedom and an experimental clamped panel structure. The technique is essentially a derivative of the Restoring Force Surface method and involves a non-linear curve fit performed in modal space. The effectiveness of the resulting reduced order model in representing the non-linear characteristics of the system is demonstrated. The potential of the approach for the identification of large continuous non-linear systems is also discussed. [less ▲]

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See detailUsing passive nonlinear targeted energy transfer to stabilize drill-stringsystems
Viguié, Régis ULg; Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg et al

in Mechanical Systems & Signal Processing (2009), 23

Torsional vibrations of drill strings used in drilling oil and gas wells arises from a complex interaction of the dynamics of the drilling structure with speed-dependent effective rock-cutting forces ... [more ▼]

Torsional vibrations of drill strings used in drilling oil and gas wells arises from a complex interaction of the dynamics of the drilling structure with speed-dependent effective rock-cutting forces. These forces are often difficult to model, and contribute substantially to the instability problems of controlling the drilling operation so as to produce steady cutting. In this work we show how nonlinear passive targeted energy transfer to a lightweight attachment can be used to passively control these instabilities. This is performed by means of a nonlinear energy sink (NES), a lightweight attachment which has been shown to be effective in reducing or even completely eliminating self-excited motions in aeroelastic and other systems. The NES is a completely passive, inherently broadband vibration absorber capable of attracting and dissipating vibrational energy from the primary structure to which it is attached, in this case a nonlinear discontinuous model of a drill-string system. In this paper we describe a prototypical drill string-NES system, briefly discuss some of the analytical and computational tools suitable for its analysis, and then concentrate on mathematical results on the efficacy of the NES in this application and their physical interpretation. [less ▲]

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See detailNonlinear normal modes, Part 2: Toward a pratical computation using numerical continuation techniques
Peeters, Maxime ULg; Viguié, Régis ULg; Sérandour, Guillaume ULg et al

in Mechanical Systems & Signal Processing (2009), 23

The conceptofnonlinearnormalmodes(NNMs)isdiscussedinthepresentpaperandits companion,PartI.OnereasonofthestilllimiteduseofNNMsinstructuraldynamicsis that theircomputationisoftenregardedasimpractical ... [more ▼]

The conceptofnonlinearnormalmodes(NNMs)isdiscussedinthepresentpaperandits companion,PartI.OnereasonofthestilllimiteduseofNNMsinstructuraldynamicsis that theircomputationisoftenregardedasimpractical.However,whenresortingto numericalalgorithms,weshowthattheNNMcomputationispossiblewithlimited implementationeffort,whichpavesthewaytoapracticalmethodfordeterminingthe NNMsofnonlinearmechanicalsystems.Theproposedalgorithmreliesontwomain techniques,namelyashootingprocedureandamethodforthecontinuationofNNM motions. Thealgorithmisdemonstratedusingfourdifferentmechanicalsystems,a weakly andastronglynonlineartwo-degree-of-freedomsystem,asimplifieddiscrete modelofanonlinearbladeddiskandanonlinearcantileverbeamdiscretizedbythefinite elementmethod. [less ▲]

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See detailNonlinear normal modes, Part 1: Useful framework for the structural dynamicist
Kerschen, Gaëtan ULg; Peeters, Maxime ULg; Golinval, Jean-Claude ULg et al

in Mechanical Systems & Signal Processing (2009), 23

The conceptofnonlinearnormalmodes(NNMs)isdiscussedinthepresentpaperandits companion,PartII.BecausethereisvirtuallynoapplicationoftheNNMstolarge-scale engineeringstructures ... [more ▼]

The conceptofnonlinearnormalmodes(NNMs)isdiscussedinthepresentpaperandits companion,PartII.BecausethereisvirtuallynoapplicationoftheNNMstolarge-scale engineeringstructures,thesepapersareanattempttohighlightseveralaspectsthat mightdrivetheirdevelopmentinthefuture.Specifically,wesupportthat(i)numerical methodsforthecontinuationofperiodicsolutionspavethewayforaneffectiveand practical computationofNNMs,and(ii)time–frequencyanalysisisparticularlysuitable fortheanalysisoftheresultingdynamics.Anotherobjectiveofthepresentpaperisto describe,insimpleterms,andtoillustratethefundamentalpropertiesofNNMs.Thisis achievedtoconvincethestructuraldynamicistnotnecessarilyacquaintedwiththemthat theyareausefulframeworkfortheanalysisofnonlinearvibratingstructures. & 2008ElsevierLtd.Allrightsreserved [less ▲]

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See detailOutput-only modal analysis using blind source separation techniques
Poncelet, Fabien ULg; Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg et al

in Mechanical Systems & Signal Processing (2007), 21(6), 2335-2358

The present study carries out output-only modal analysis using two blind source separation (BSS) techniques, namely independent component analysis and second-order blind identification. The concept of ... [more ▼]

The present study carries out output-only modal analysis using two blind source separation (BSS) techniques, namely independent component analysis and second-order blind identification. The concept of virtual source is exploited and renders the application of these BSS techniques possible. The proposed modal analysis method is illustrated using numerical and experimental examples. (c) 2007 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPhysical interpretation of independent component analysis in structural dynamics
Kerschen, Gaëtan ULg; Poncelet, Fabien ULg; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2007), 21

This paper focuses on the relation between the vibration modes of mechanical systems and the modes computed through a blind source separation technique called independent component analysis (ICA). For ... [more ▼]

This paper focuses on the relation between the vibration modes of mechanical systems and the modes computed through a blind source separation technique called independent component analysis (ICA). For free and random vibrations of weakly damped systems, a one-to-one relationship between the vibration modes and the ICA modes is demonstrated using the concept of virtual source. Based on this theoretical link, a time-domain structural system identification technique is proposed and is illustrated using numerical examples. [less ▲]

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See detailNull subspace-based damage detection of structures using vibration measurements
Yan, Ai-Min; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2006), 20(3), 611-626

A damage detection method of mechanical system based on subspace identification concepts and statistical process techniques is presented. The aim is to propose a method that is sensitive to small-sized ... [more ▼]

A damage detection method of mechanical system based on subspace identification concepts and statistical process techniques is presented. The aim is to propose a method that is sensitive to small-sized structural damages and suitable for on-line monitoring. Measured time-responses of structures subjected to artificial or environmental vibrations are assembled to form the Hankel matrix, which is further factorised by performing singular-value decomposition to obtain characteristic subspaces. It may be demonstrated that the structural responses are mainly located in the active subspace defined by the first principal components, which is orthonormal to the null subspace defined by the remaining principal components. If no structural damage occurs, the orthonormality relation between the subspaces remains valid with small residues when consecutive data sets are compared, and these residues may be evaluated by the proposed damage indicators. The method is validated using an experimental mock-up of an airplane subjected to different levels of damages simulated. It is also applied in environmental vibration testing of a street lighting device to monitor structural fatigue evolution. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPast, present and future of nonlinear system identification in structural dynamics
Kerschen, Gaëtan ULg; Worden, Keith; Vakakis, Alexander F. et al

in Mechanical Systems & Signal Processing (2006), 20(3), 505-592

This survey paper contains a review of the past and recent developments in system identification of nonlinear dynamical structures. The objective is to present some of the popular approaches that have ... [more ▼]

This survey paper contains a review of the past and recent developments in system identification of nonlinear dynamical structures. The objective is to present some of the popular approaches that have been proposed in the technical literature, to illustrate them using numerical and experimental applications, to highlight their assets and limitations and to identify future directions in this research area. The fundamental differences between linear and nonlinear oscillations are also detailed in a tutorial. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailStructural damage diagnosis under varying environmental conditions - Part II: local PCA for non-linear cases
Yan, A. M.; Kerschen, Gaëtan ULg; De Boe, P. et al

in Mechanical Systems & Signal Processing (2005), 19(4), 865-880

It is well known that changes in vibration features of structures due to damage may be masked by the effects of environmental variations. This influence has to be eliminated in the structural health ... [more ▼]

It is well known that changes in vibration features of structures due to damage may be masked by the effects of environmental variations. This influence has to be eliminated in the structural health-monitoring process, especially when a long-term in situ monitoring is expected. In the companion paper [1] a linear method based on principal component analysis (PCA) has been proposed and has shown encouraging results for linear or even weakly non-linear cases. The present paper concerns a further extension of the proposed method to handle non-linear cases, which may be encountered in some complex structures. The method involves a two-step procedure, namely a clustering of the data space into several regions and then the application of PCA La each local region. The application of local PCA allows performing a piecewise linearisation of the non-linear problem. A close look at the choice of the distortion function used in data clustering leads to two new clustering strategies. Whereas the first strategy is specifically suitable for the application treated in this paper, the second one is more general. The local PCA-based damage detection method is applied for the structural health monitoring of a real bridge using vibration data measured in situ over a one-year period. 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailStructural damage diagnosis under varying environmental conditions - Part I: A linear analysis
Yan, Ai-Min; Kerschen, Gaëtan ULg; De Boe, Pascal et al

in Mechanical Systems & Signal Processing (2005), 19(4), 847-864

A damage detection method is proposed for structural health monitoring under varying environmental and operational conditions. The method is based on principal component analysis (PICA) applied to ... [more ▼]

A damage detection method is proposed for structural health monitoring under varying environmental and operational conditions. The method is based on principal component analysis (PICA) applied to vibration features identified during the monitoring of the structure. The advantage of the method is that it does not require to measure environmental parameters because they are taken into account as embedded variables. The number of principal components of the vibration features is implicitly assumed to correspond to the number of independent environmental factors. Since the environmental effects may be effectively eliminated by the proposed procedure, the residual error of the PCA prediction model remains small if the structure is healthy, and it increases significantly when structural damage occurs. Novelty analysis on the residual errors provides a statistical indication of damage. In the present paper, the environmental conditions are assumed to have a linear (or weakly non-linear) effect on the vibration features, and the PCA-based damage detection method is illustrated using computer-simulated and laboratory testing data. The extension of the proposed method to non-linear cases is addressed in a companion paper where the efficiency of the method is verified using data obtained from a 1-year in situ monitoring of a bridge. 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailModal identification and damage detection using the data-driven stochastic subspace and ARMAV methods
Bodeux, Jean-Bernard; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2003), 17(1), 83-89

This paper presents results of modal identification and damage detection on the Steel-Quake structure using the autoregressive moving average vector and data-driven stochastic subspace methods. The ... [more ▼]

This paper presents results of modal identification and damage detection on the Steel-Quake structure using the autoregressive moving average vector and data-driven stochastic subspace methods. The methods directly work with the recorded time signals and allow to analyse linear systems where only the system output is measured, while the input is unknown but produced by uncorrelated random signals. These techniques can also be used directly to analyse data obtained from the free response of linear systems. (C) 2003 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailResults obtained by minimising natural frequency and mac-value errors of a beam model
Thonon, C.; Golinval, Jean-Claude ULg

in Mechanical Systems & Signal Processing (2003), 17(1), 65-72

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

This paper reports the procedure followed by the 'LTAS-Vibrations et Identification des Structures' research group to generate a low-order finite element (FE) model of the GARTEUR SM-AG19 structure. The model is made of beam elements, local inertia and rigid body elements. The philosophy of the updating method is first based on the correlation of the experimental data with the results of the FE model and on the localisation of errors in the model. Updating parameters are then selected using eigenvalue sensitivity and model error localisation analyses. After updating, the quality of the FE model is assessed in terms of accuracy of the response prediction to structural modifications. (C) 2003 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailCost Action F3 'Structural Dynamics' (1997-2001) - An European Co-operation in the Field of Science and Technology
Golinval, Jean-Claude ULg; Link, M.

in Mechanical Systems & Signal Processing (2003), 17(1), 3-7

This section is concerned with presenting the objective, the scientific programme and the organisation of COST Action F3 in Structural Dynamics. (C) 2003 Elsevier Science Ltd. All rights reserved.

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