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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 24 Feb 2024 09:02:06 GMT2024-02-24T09:02:06ZComparison of least squares and exponential sine sweep methods for Parallel Hammerstein Models estimation
http://hdl.handle.net/10985/12468
Comparison of least squares and exponential sine sweep methods for Parallel Hammerstein Models estimation
REBILLAT, Marc; SCHOUKENS, Maarten
Linearity is a common assumption for many real-life systems, but in many cases the nonlinear behavior of systems cannot be ignored and must be modeled and estimated. Among the various existing classes of nonlinear models, Parallel Hammerstein Models (PHM) are interesting as they are at the same time easy to interpret as well as to estimate. One way to estimate PHM relies on the fact that the estimation problem is linear in the parameters and thus that classical least squares (LS) estimation algorithms can be used. In that area, this article introduces a regularized LS estimation algorithm inspired on some of the recently developed regularized impulse response estimation techniques. Another mean to estimate PHM consists in using parametric or non-parametric exponential sine sweeps (ESS) based methods. These methods (LS and ESS) are founded on radically different mathematical backgrounds but are expected to tackle the same issue. A methodology is proposed here to compare them with respect to (i) their accuracy, (ii) their computational cost, and (iii) their robustness to noise. Tests are performed on simulated systems for several values of methods respective parameters and of signal to noise ratio. Results show that, for a given set of data points, the ESS method is less demanding in computational resources than the LS method but that it is also less accurate. Furthermore, the LS method needs parameters to be set in advance whereas the ESS method is not subject to conditioning issues and can be fully non-parametric. In summary, for a given set of data points, ESS method can provide a first, automatic, and quick overview of a nonlinear system than can guide more computationally demanding and precise methods, such as the regularized LS one proposed here.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/124682017-01-01T00:00:00ZREBILLAT, MarcSCHOUKENS, MaartenLinearity is a common assumption for many real-life systems, but in many cases the nonlinear behavior of systems cannot be ignored and must be modeled and estimated. Among the various existing classes of nonlinear models, Parallel Hammerstein Models (PHM) are interesting as they are at the same time easy to interpret as well as to estimate. One way to estimate PHM relies on the fact that the estimation problem is linear in the parameters and thus that classical least squares (LS) estimation algorithms can be used. In that area, this article introduces a regularized LS estimation algorithm inspired on some of the recently developed regularized impulse response estimation techniques. Another mean to estimate PHM consists in using parametric or non-parametric exponential sine sweeps (ESS) based methods. These methods (LS and ESS) are founded on radically different mathematical backgrounds but are expected to tackle the same issue. A methodology is proposed here to compare them with respect to (i) their accuracy, (ii) their computational cost, and (iii) their robustness to noise. Tests are performed on simulated systems for several values of methods respective parameters and of signal to noise ratio. Results show that, for a given set of data points, the ESS method is less demanding in computational resources than the LS method but that it is also less accurate. Furthermore, the LS method needs parameters to be set in advance whereas the ESS method is not subject to conditioning issues and can be fully non-parametric. In summary, for a given set of data points, ESS method can provide a first, automatic, and quick overview of a nonlinear system than can guide more computationally demanding and precise methods, such as the regularized LS one proposed here.Vibroacoustics of the piano soundboard : (Non)linearity and modal properties in the low- and mid-frequency ranges
http://hdl.handle.net/10985/8195
Vibroacoustics of the piano soundboard : (Non)linearity and modal properties in the low- and mid-frequency ranges
EGE, Kerem; BOUTILLON, Xavier; REBILLAT, Marc
The piano soundboard transforms the string vibration into sound and therefore, its vibrations are of primary importance for the sound characteristics of the instrument. An original vibro-acoustical method is presented to isolate the soundboard nonlinearity from that of the exciting device (here: a loudspeaker) and to measure it. The nonlinear part of the soundboard response to an external excitation is quantitatively estimated for the ﬁrst time, at 40 dB below the linear part at the ff nuance. Given this essentially linear response, a modal identiﬁcation is performed up to 3 kHz by means of a novel high resolution modal analysis technique [K. Ege, X. Boutillon, B. David, High-resolution modal analysis, Journal of Sound and Vibration 325 (4–5) (2009) 852–869]. Modal dampings (which, so far, were unknown for the piano in this frequency range) are determined in the mid-frequency domain where FFT-based methods fail to evaluate them with an acceptable precision. They turn out to be close to those imposed by wood. A ﬁnite-element modelling of the soundboard is also presented. The low-order modal shapes and the comparison between the corresponding experimental and numerical modal frequencies suggest that the boundary conditions can be considered as blocked, except at very low frequencies. The frequency-dependency of the estimated modal densities and the observation of modal shapes reveal two well-separated regimes. Below 1 kHz, the soundboard vibrates more or less like a homogeneous plate. Above that limit, the structural waves are conﬁned by ribs, as already noticed by several authors, and localised in restricted areas (one or a few inter-rib spaces), presumably due to a slightly irregular spacing of the ribs across the soundboard.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/81952013-01-01T00:00:00ZEGE, KeremBOUTILLON, XavierREBILLAT, MarcThe piano soundboard transforms the string vibration into sound and therefore, its vibrations are of primary importance for the sound characteristics of the instrument. An original vibro-acoustical method is presented to isolate the soundboard nonlinearity from that of the exciting device (here: a loudspeaker) and to measure it. The nonlinear part of the soundboard response to an external excitation is quantitatively estimated for the ﬁrst time, at 40 dB below the linear part at the ff nuance. Given this essentially linear response, a modal identiﬁcation is performed up to 3 kHz by means of a novel high resolution modal analysis technique [K. Ege, X. Boutillon, B. David, High-resolution modal analysis, Journal of Sound and Vibration 325 (4–5) (2009) 852–869]. Modal dampings (which, so far, were unknown for the piano in this frequency range) are determined in the mid-frequency domain where FFT-based methods fail to evaluate them with an acceptable precision. They turn out to be close to those imposed by wood. A ﬁnite-element modelling of the soundboard is also presented. The low-order modal shapes and the comparison between the corresponding experimental and numerical modal frequencies suggest that the boundary conditions can be considered as blocked, except at very low frequencies. The frequency-dependency of the estimated modal densities and the observation of modal shapes reveal two well-separated regimes. Below 1 kHz, the soundboard vibrates more or less like a homogeneous plate. Above that limit, the structural waves are conﬁned by ribs, as already noticed by several authors, and localised in restricted areas (one or a few inter-rib spaces), presumably due to a slightly irregular spacing of the ribs across the soundboard.Wave damping and evanescence: how to combine the spatial and temporal visions of the same problem? 1
http://hdl.handle.net/10985/10854
Wave damping and evanescence: how to combine the spatial and temporal visions of the same problem? 1
BALMES, Etienne; REBILLAT, Marc; ARLAUD, Elodie
It is proposed to analyze the forced response of periodic structures using a 2D Fourier transform using continuous time and discrete space. The simple example of compression waves is used to show that this response can be used to define poles in the wavenumber domain corresponding to evanescent waves or poles in the frequency domain corresponding to damped periodic modes. Link with classical computational methods based on FEM models of cells was done for both the periodic solution and wave based approach (SAFE, WFE). Two examples are analyzed in more detail: a simple train track model exhibiting a band-gap and the more complex case of a honeycomb panel where cell wall bending occurs within the band of interest.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/108542016-01-01T00:00:00ZBALMES, EtienneREBILLAT, MarcARLAUD, ElodieIt is proposed to analyze the forced response of periodic structures using a 2D Fourier transform using continuous time and discrete space. The simple example of compression waves is used to show that this response can be used to define poles in the wavenumber domain corresponding to evanescent waves or poles in the frequency domain corresponding to damped periodic modes. Link with classical computational methods based on FEM models of cells was done for both the periodic solution and wave based approach (SAFE, WFE). Two examples are analyzed in more detail: a simple train track model exhibiting a band-gap and the more complex case of a honeycomb panel where cell wall bending occurs within the band of interest.On the variation of interaural time differences with frequency
http://hdl.handle.net/10985/10702
On the variation of interaural time differences with frequency
BENICHOUX, Victor; REBILLAT, Marc; BRETTE, Romain
Interaural time difference (ITD) is a major cue to sound localization in humans and animals. For a given subject and position in space, ITD depends on frequency. This variation is analyzed here using a head related transfer functions (HRTFs) database collected from the literature and comprising human HRTFs from 130 subjects and animal HRTFs from six specimens of different species. For humans, the ITD is found to vary with frequency in a way that shows consistent differences with respect to a spherical head model. Maximal ITD values were found to be about 800 ls in low frequencies and 600 ls in high frequencies. The ITD variation with frequency (up to 200 ls for some positions) occurs within the frequency range where ITD is used to judge the lateral position of a sound source. In addition, ITD varies substantially within the bandwidth of a single auditory filter, leading to systematic differences between envelope and fine-structure ITDs. Because the frequency-dependent pattern of ITD does not display spherical symmetries, it potentially provides cues to elevation and resolves front/back confusion. The fact that the relation between position and ITDs strongly depends on the sound’s spectrum in turn suggests that humans and animals make use of this relationship for the localization of sounds.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/107022016-01-01T00:00:00ZBENICHOUX, VictorREBILLAT, MarcBRETTE, RomainInteraural time difference (ITD) is a major cue to sound localization in humans and animals. For a given subject and position in space, ITD depends on frequency. This variation is analyzed here using a head related transfer functions (HRTFs) database collected from the literature and comprising human HRTFs from 130 subjects and animal HRTFs from six specimens of different species. For humans, the ITD is found to vary with frequency in a way that shows consistent differences with respect to a spherical head model. Maximal ITD values were found to be about 800 ls in low frequencies and 600 ls in high frequencies. The ITD variation with frequency (up to 200 ls for some positions) occurs within the frequency range where ITD is used to judge the lateral position of a sound source. In addition, ITD varies substantially within the bandwidth of a single auditory filter, leading to systematic differences between envelope and fine-structure ITDs. Because the frequency-dependent pattern of ITD does not display spherical symmetries, it potentially provides cues to elevation and resolves front/back confusion. The fact that the relation between position and ITDs strongly depends on the sound’s spectrum in turn suggests that humans and animals make use of this relationship for the localization of sounds.Estimation of the low-frequency components of the head-related transfer functions of animals from photographs
http://hdl.handle.net/10985/8229
Estimation of the low-frequency components of the head-related transfer functions of animals from photographs
REBILLAT, Marc; BENICHOUX, Victor; BRETTE, Romain; OTANI, Makoto; KERIVEN, Renaud
Reliable animal head-related transfer function (HRTF) estimation procedures are needed for several practical applications. For example, to investigate the neuronal mechanisms of sound localization using virtual acoustic spaces, or to have a quantitative description of the di erent localization cues available to a given animal species. Here two established techniques are combined to estimate an animal's HRTF from photographs by taking into account as much morphological detail as possible. The rst step of the method consists in building a 3D-model of the animal from pictures taken with a standard camera. The HRTFs are then estimated by means of a rapid boundary-element-method implementation. This combined method is validated on a taxidermist model of a cat by comparing binaural and monaural localization cues extracted from estimated and measured HRTFs. It is shown that it provides a reliable way to estimate low-frequency HRTF, which are di cult to obtain with standard acoustical measurements procedures because of re ections.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/82292014-01-01T00:00:00ZREBILLAT, MarcBENICHOUX, VictorBRETTE, RomainOTANI, MakotoKERIVEN, RenaudReliable animal head-related transfer function (HRTF) estimation procedures are needed for several practical applications. For example, to investigate the neuronal mechanisms of sound localization using virtual acoustic spaces, or to have a quantitative description of the di erent localization cues available to a given animal species. Here two established techniques are combined to estimate an animal's HRTF from photographs by taking into account as much morphological detail as possible. The rst step of the method consists in building a 3D-model of the animal from pictures taken with a standard camera. The HRTFs are then estimated by means of a rapid boundary-element-method implementation. This combined method is validated on a taxidermist model of a cat by comparing binaural and monaural localization cues extracted from estimated and measured HRTFs. It is shown that it provides a reliable way to estimate low-frequency HRTF, which are di cult to obtain with standard acoustical measurements procedures because of re ections.A Spherical Cross-Channel Algorithm for Binaural Sound Localization
http://hdl.handle.net/10985/7400
A Spherical Cross-Channel Algorithm for Binaural Sound Localization
VINA, Carlos; ARGENTIERI, Sylvain; REBILLAT, Marc
This paper proposes a sound localization algorithm inspired by a cross-channel algorithm first studied by MacDonald et. al in 2008. The original algorithm assumes that the Head Related Transfer Functions (HRTFs) of the robotic head under study are precisely known, which is rarely the case in practice. Following the idea that any head is more or less spherical, the above assumption is relaxed by using HRTFs computed using a simple spherical head model with the same head radius as the robot head. In order to evaluate the proposed approach in realistic noisy conditions, an isotropic noise field is also computed and a precise definition of the Signal to Noise Ratio (SNR) in a binaural context is outlined. All these theoretical developments are finally assessed with simulated and experimental signals. Despite its simplicity, the proposed approach appears to be robust to noise and to provide reliable sound localization estimations in the frontal azimuthal plane.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/74002013-01-01T00:00:00ZVINA, CarlosARGENTIERI, SylvainREBILLAT, MarcThis paper proposes a sound localization algorithm inspired by a cross-channel algorithm first studied by MacDonald et. al in 2008. The original algorithm assumes that the Head Related Transfer Functions (HRTFs) of the robotic head under study are precisely known, which is rarely the case in practice. Following the idea that any head is more or less spherical, the above assumption is relaxed by using HRTFs computed using a simple spherical head model with the same head radius as the robot head. In order to evaluate the proposed approach in realistic noisy conditions, an isotropic noise field is also computed and a precise definition of the Signal to Noise Ratio (SNR) in a binaural context is outlined. All these theoretical developments are finally assessed with simulated and experimental signals. Despite its simplicity, the proposed approach appears to be robust to noise and to provide reliable sound localization estimations in the frontal azimuthal plane.Contrôle santé des structures basé sur la signature dynamique non-linéaire de dommages
http://hdl.handle.net/10985/10368
Contrôle santé des structures basé sur la signature dynamique non-linéaire de dommages
REBILLAT, Marc
La mise en place de procédures de contrôle automatisé de l’endommagement de structures issues de l’aéronautique ou du génie civil constitue une thématique émergente nommée « Contrôle de la santé des structures » (SHM : « Structural Health Monitoring »). Le déploiement de ces procédures laisse présager d’importantes améliorations en termes de sécurité ainsi qu’une réduction substantielle des couts de maintenance. Les procédures de SHM sont habituellement divisées séquentiellement en quatre étapes : détection, localisation, classification, puis quantification de l’endommagement. Les dommages apparaissant dans ces structures sont à l’origine de non-linéarités dans la réponse dynamique de ces structures qui ne sont pour l’instant pas ou peu utilisées à des fins de SHM. Nous verrons ainsi dans ce séminaire que, s’il est possible d’estimer efficacement la signature non-linéaire des dommages, cette information s’avère être un indicateur extrêmement sensible pour la surveillance des dommages. Du point de vue mathématique les travaux présentés ici s’appuient sur une classe de modèles non-linéaires par bloc prometteuse : les modèles de Hammerstein en parallèle. L’intérêt de cette classe de modèles est qu’elle est à la fois simple à estimer et représentative d’un large panel de structures endommagées. Nous verrons ainsi, qu’à partir d’une représentation non-linéaire plus riche tirée de ces modèles, des algorithmes de SHMs liés aux phases de détection, de classification, et de quantification des dommages peuvent être développés. Ces algorithmes seront illustrés dans des contextes « aéronautique » ou « génie civil » sur des données numériques et expérimentales.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/103682015-01-01T00:00:00ZREBILLAT, MarcLa mise en place de procédures de contrôle automatisé de l’endommagement de structures issues de l’aéronautique ou du génie civil constitue une thématique émergente nommée « Contrôle de la santé des structures » (SHM : « Structural Health Monitoring »). Le déploiement de ces procédures laisse présager d’importantes améliorations en termes de sécurité ainsi qu’une réduction substantielle des couts de maintenance. Les procédures de SHM sont habituellement divisées séquentiellement en quatre étapes : détection, localisation, classification, puis quantification de l’endommagement. Les dommages apparaissant dans ces structures sont à l’origine de non-linéarités dans la réponse dynamique de ces structures qui ne sont pour l’instant pas ou peu utilisées à des fins de SHM. Nous verrons ainsi dans ce séminaire que, s’il est possible d’estimer efficacement la signature non-linéaire des dommages, cette information s’avère être un indicateur extrêmement sensible pour la surveillance des dommages. Du point de vue mathématique les travaux présentés ici s’appuient sur une classe de modèles non-linéaires par bloc prometteuse : les modèles de Hammerstein en parallèle. L’intérêt de cette classe de modèles est qu’elle est à la fois simple à estimer et représentative d’un large panel de structures endommagées. Nous verrons ainsi, qu’à partir d’une représentation non-linéaire plus riche tirée de ces modèles, des algorithmes de SHMs liés aux phases de détection, de classification, et de quantification des dommages peuvent être développés. Ces algorithmes seront illustrés dans des contextes « aéronautique » ou « génie civil » sur des données numériques et expérimentales.Exponential sine sweeps for the autonomous estimation of nonlinearities and errors assessment by bootstrap Application to thin vibrating structures
http://hdl.handle.net/10985/10369
Exponential sine sweeps for the autonomous estimation of nonlinearities and errors assessment by bootstrap Application to thin vibrating structures
REBILLAT, Marc; EGE, Kerem; GALLO, Maxime; ANTONI, Jérôme
Vibrating structures are generally assumed to behave linearly and in a noise-free environment. This is in practice not perfectly the case. First, nonlinear phenomena such as jump phenomenon, hysteresis or internal resonance appear when the transverse vibration of a bi-dimensional structure exceeds amplitudes in the order of magnitude of its thickness. Secondly, the presence of plant noise is a natural phenomenon that is unavoidable for all experimental measurements. In order to perform reliable measurements of vibrating mechanical structures one should thus keep in mind these two issues and care about them. However, it turns out that they are actually coupled. Indeed, all the noise that is not correctly removed from the measurements could be misinterpreted as nonlinearities, thus polluting measurements. And if nonlinearities are not accurately estimated, they will end up within the noise signal and information about the structure under study will be lost. We thus try here to solve simultaneously both issues. The underlying idea consists in extracting the maximum of available linear and nonlinear deterministic information from measurements without misinterpreting noise. The aim of this talk is thus to provide a methodology that allows for the autonomous estimation of nonlinearities and errors assessment by bootstrap on a given vibrating structure. Nonlinearities are estimated by means of a block-oriented nonlinear model approach based on parallel Hammerstein models and on exponential sine sweeps. Estimation errors are simultaneously assessed using repetitions of the input signal (multi exponential sine sweeps) as the input of a bootstrap procedure. Mathematical foundations and practical implementation of the method are discussed on an experimental example. The experiment chosen here consists in exciting a steel plate under various boundary conditions with exponential sine sweeps and at different levels, in order to assess the evolutions of nonlinearities and of signal to noise ratio over a wide range of frequencies and input amplitudes.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/103692015-01-01T00:00:00ZREBILLAT, MarcEGE, KeremGALLO, MaximeANTONI, JérômeVibrating structures are generally assumed to behave linearly and in a noise-free environment. This is in practice not perfectly the case. First, nonlinear phenomena such as jump phenomenon, hysteresis or internal resonance appear when the transverse vibration of a bi-dimensional structure exceeds amplitudes in the order of magnitude of its thickness. Secondly, the presence of plant noise is a natural phenomenon that is unavoidable for all experimental measurements. In order to perform reliable measurements of vibrating mechanical structures one should thus keep in mind these two issues and care about them. However, it turns out that they are actually coupled. Indeed, all the noise that is not correctly removed from the measurements could be misinterpreted as nonlinearities, thus polluting measurements. And if nonlinearities are not accurately estimated, they will end up within the noise signal and information about the structure under study will be lost. We thus try here to solve simultaneously both issues. The underlying idea consists in extracting the maximum of available linear and nonlinear deterministic information from measurements without misinterpreting noise. The aim of this talk is thus to provide a methodology that allows for the autonomous estimation of nonlinearities and errors assessment by bootstrap on a given vibrating structure. Nonlinearities are estimated by means of a block-oriented nonlinear model approach based on parallel Hammerstein models and on exponential sine sweeps. Estimation errors are simultaneously assessed using repetitions of the input signal (multi exponential sine sweeps) as the input of a bootstrap procedure. Mathematical foundations and practical implementation of the method are discussed on an experimental example. The experiment chosen here consists in exciting a steel plate under various boundary conditions with exponential sine sweeps and at different levels, in order to assess the evolutions of nonlinearities and of signal to noise ratio over a wide range of frequencies and input amplitudes.Damage localization in composite plates using canonical polyadic decomposition of Lamb wave difference signals tensor
http://hdl.handle.net/10985/23324
Damage localization in composite plates using canonical polyadic decomposition of Lamb wave difference signals tensor
REBILLAT, Marc; MECHBAL, Nazih
Monitoring in real-time and autonomously the health state of aeronautic structures is referred to as Structural Health Monitoring (SHM) and is a process decomposed in four steps: damage detection, localization, classification, and quantification. Structures under study are here composite structures representative of aeronautic applications and the focus is put on the localization step of the SHM process. The fact that SHM data are naturally three-way tensors is here investigated for this purpose. It is demonstrated that under classical assumptions regarding wave propagation, the canonical polyadic decomposition of rank 2 of the tensor built from the phase of the difference signals between a healthy and damaged states provides direct access to the distances between the piezoelectric elements and the damage. This property is used here to propose an original and robust tensor-based damage localization algorithm. This algorithm is successfully validated on experimental data coming from composite plates with mounted piezoelectric elements and compared with a classical localization algorithm based on triangulation.
Wed, 01 Aug 2018 00:00:00 GMThttp://hdl.handle.net/10985/233242018-08-01T00:00:00ZREBILLAT, MarcMECHBAL, NazihMonitoring in real-time and autonomously the health state of aeronautic structures is referred to as Structural Health Monitoring (SHM) and is a process decomposed in four steps: damage detection, localization, classification, and quantification. Structures under study are here composite structures representative of aeronautic applications and the focus is put on the localization step of the SHM process. The fact that SHM data are naturally three-way tensors is here investigated for this purpose. It is demonstrated that under classical assumptions regarding wave propagation, the canonical polyadic decomposition of rank 2 of the tensor built from the phase of the difference signals between a healthy and damaged states provides direct access to the distances between the piezoelectric elements and the damage. This property is used here to propose an original and robust tensor-based damage localization algorithm. This algorithm is successfully validated on experimental data coming from composite plates with mounted piezoelectric elements and compared with a classical localization algorithm based on triangulation.Detection, localization, and quantification of corrosion damage using Lamb Waves for the structural health monitoring of aluminum aeronautics structures
http://hdl.handle.net/10985/23345
Detection, localization, and quantification of corrosion damage using Lamb Waves for the structural health monitoring of aluminum aeronautics structures
LIEGEY, Julie; BRIAND, William; REBILLAT, Marc; EL MAY, Mohamed; DEVOS, Olivier; MECHBAL, Nazih
Corrosion is a major concern for the aeronautic industry and providing structures with the intrinsic ability to monitor autonomously their health state is a major actual academic and industrial challenge. In this paper, detection, localization, and
quantification of a damage representative of a corrosion damage using Lamb waves emitted and received by piezoelectric elements for the purpose of structural health monitoring of aeronautics aluminum structures is addressed. Semi-spherical holes of different sizes representing a calibrated corrosion pit are manufactured on a 2024 aluminum plate with four piezoelectric sensors bonded on it. Lamb waves are then recorded with one element used as an actuator and the other ones being used as sensors. A dedicated recording system provided by Cedrat Technologies is used to acquire Lamb waves data. It is demonstrated on this representative example that by using actual algorithms from the SHM literature, it is possible to detect, localize, and quantify this damage representative of an actual corrosion damage. These preliminary results are very encouraging before monitoring actual corrosion and fatigue damages which constitutes the main objective of the COQTEL project.
Mon, 04 Jul 2022 00:00:00 GMThttp://hdl.handle.net/10985/233452022-07-04T00:00:00ZLIEGEY, JulieBRIAND, WilliamREBILLAT, MarcEL MAY, MohamedDEVOS, OlivierMECHBAL, NazihCorrosion is a major concern for the aeronautic industry and providing structures with the intrinsic ability to monitor autonomously their health state is a major actual academic and industrial challenge. In this paper, detection, localization, and
quantification of a damage representative of a corrosion damage using Lamb waves emitted and received by piezoelectric elements for the purpose of structural health monitoring of aeronautics aluminum structures is addressed. Semi-spherical holes of different sizes representing a calibrated corrosion pit are manufactured on a 2024 aluminum plate with four piezoelectric sensors bonded on it. Lamb waves are then recorded with one element used as an actuator and the other ones being used as sensors. A dedicated recording system provided by Cedrat Technologies is used to acquire Lamb waves data. It is demonstrated on this representative example that by using actual algorithms from the SHM literature, it is possible to detect, localize, and quantify this damage representative of an actual corrosion damage. These preliminary results are very encouraging before monitoring actual corrosion and fatigue damages which constitutes the main objective of the COQTEL project.