Double function of integrated piezoelectric sensors for ageing and damage monitoring composite structures / Philippe Guy in MATERIAUX & TECHNIQUES, N° Hors série (2002)

[article]  inMATERIAUX & TECHNIQUES > N° Hors série (2002) . - p. 33-35 Titre : Double function of integrated piezoelectric sensors for ageing and damage monitoring composite structures Type de document : texte imprimé Auteurs : Philippe Guy, Auteur ; Thomas Monnier, Auteur ; Jean-Claude Baboux, Auteur ; Yves Jayet, Auteur Année de publication : 2003 Article en page(s) : p. 33-35 Note générale : Bibliogr. Langues : Français (fre) Catégories : Composites -- Détérioration Détection de défauts (Ingénierie) Matériaux -- Fatigue Piézomètres Index. décimale : 620.11 Matériaux (propriétés, résistance) Résumé : The life duration of a structure depends on both the homogeneously distributed degradation of its mechanical properties during its life (ageing) and the presence of localised defects such as cracks or delaminations. Previous studies, described an ultrasonic health monitoring method enabling the recovery of both kinds of information. The method is based upon an integrated piezoelectric element into the plate-like composite structure which avoids coupling reproducibility problems. The element dimensions are determined in order to uncouple the frequency ranges of the thickness and radial vibration modes. The thickness mode is then exploited to monitor the homogeneous ageing of the structure through electrical impedance measurement. Whereas the radial vibration, are used to launch and detect Lamb waves, which are known to propagate over long distances. The guided waves also have the advantage to be multimodal, so the various propagating modes offer a specific sensitivity to the different kinds of defects that a structure can host. The previous papers dealt respectively to each of the two possible monitoring modes of the system. The present work focuses more particularly on the specific problems related to the simultaneous implementation of both aspects. Furthermore, the influence of the material properties upon the limitations of each kind of monitoring will be discussed in relation with the characteristics of the waves that the structure can propagate. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10274 [article]

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Linear and nonlinear ultrasonics for material damage evaluation and health monitoring / Rachid El Guerjouma in MATERIAUX & TECHNIQUES, N° Hors série (2002)

[article]  inMATERIAUX & TECHNIQUES > N° Hors série (2002) . - p. 48-50 Titre : Linear and nonlinear ultrasonics for material damage evaluation and health monitoring Type de document : texte imprimé Auteurs : Rachid El Guerjouma, Auteur ; L. Goujon, Auteur ; H. Nachad, Auteur ; A. Faiz, Auteur ; Nathalie Godin, Auteur ; Mourad Bentahar, Auteur ; Jean-Claude Baboux, Auteur Année de publication : 2003 Article en page(s) : p. 48-50 Note générale : Bibliogr. Langues : Français (fre) Catégories : Composites Contrôle non destructif Détection de défauts (Ingénierie) Ultrasons Index. décimale : 620.11 Matériaux (propriétés, résistance) Résumé : In mechanics of material and material sciences, the early detection of damage, its non destructive characterisation and monitoring is of great importance. In this field ultrasonic waves can be very helpful especially when nonlinear ultrasonics is considered. In this work, linear and non linear ultrasonics are used for damage characterisation. Concerning linear ultrasonics, we show that velocity and linear elastic constants are good damage indicators for composites materials. For these materials, ultrasonic velocity is measured in situ during a tensile test, at the same time acoustic activity due to damage initiation and development. For other materials as metallic ones, linear ultrasonics is not sensitive enough for damage characterisation. In this case we show that nonlinear ultrasonics through the nonlinearity parameter β, is very sensitive to evaluate damage and to detect it very early. In this work we show that if linear ultrasonics through velocity measurements is a very good damage indicator especially for composite materials, nonlinear ultrasonics can be a very efficient tool for the early detection of damage and also for health monitoring. So it can greatly contribute to the understanding of damage initiation. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10276 [article]

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The health monitoring of composite materials : new approaches / P. F. Gobin in MATERIAUX & TECHNIQUES, N° Hors série (2002)

[article]  inMATERIAUX & TECHNIQUES > N° Hors série (2002) . - p. 37-41 Titre : The health monitoring of composite materials : new approaches Type de document : texte imprimé Auteurs : P. F. Gobin, Auteur ; Jean-Claude Baboux, Auteur ; Nathalie Godin, Auteur ; Michelle Salvia, Auteur ; Yves Jayet, Auteur Année de publication : 2003 Article en page(s) : p. 37-41 Note générale : Bibliogr. Langues : Français (fre) Catégories : Composites Détection de défauts (Ingénierie) Matériaux -- Détérioration Matériaux intelligents Index. décimale : 620.112 Résistance et autres propriétés des matériaux, essais non destructifs Résumé : The classical NDE techniques of periodical maintenance are just now evolving towards the continuous health monitoring of materials and structures. The on line monitoring systems have to present a small size without damage initiation risk, good sensitivity and robustness. Taking account of the relation of this approach with the more general notion of smart materials, it seems useful to extend this passive concept to a more active one specially in the case of composite materials. Effectively, if sensors are embedded in a composite structure before curing in order to monitor and optimise the processing parameters, they are able, remaining in the structure, to assume the health monitoring in the second stage of the life. Moreover, in slightly damaged systems, it becomes reasonable to use the collected results for an on line tentative prediction of the residual life. Finally in the last stage of the life, when the material is deeply damaged, it is sometimes possible to slow down, and very rarely, to heal the damage. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10275 [article]

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