Ondes de Lamb dans les milieux stratifiés : application à la surveillance in situ et en temps réel de l'endommagement de structures composites

Abstract : Because of the quality and the variety of their mechanical properties, the composite materials are now commonly replacing traditional materials. But there are many different damage processes to be observed in these kind of heterogeneous materials. Hence, the growth of their use as primary structure remains limited by the significant costs of the inspection, which are required to detect the appearance of internal defects. We sought to define an in situ non-destructive method for the health monitoring of composites, in order to achieve a better operational safety of the structures at lower cost. This active-control method agrees with the concept of Smart Materials and Structures as it consists in the integration into the host structure of sensors, for the generation and the measurement of ultrasonic waves, and associated data processing systems. As Lamb waves are the privileged information carrier in thin plates, their modelling was extended in this work to anisotropic laminated materials. The propagation and the characteristics of these dispersive modes were studied in relation to the microstructural properties and the geometry of various laminated mediums. In particular, we studied the influence of the stacking sequence of the plies on the Lamb waves dispersion curves. The realisation of instrumented plates allowed the experimental detection of artificial or more realistic defects thanks to the definition of parameters of damaging parameters, which were based on the real time analysis of the ultrasonic signatures transmitted inside the structure. The location of the defects was estimated by Lamb waves echographic measurements. Finally, we sought to assess the relative sensitivity of the fundamental Lamb modes by the use of the numerical simulation of the interaction between these guided waves and various types of localised defects, through the two dimensional Finite Elements Method.
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Mechanics [physics.med-ph]. INSA de Lyon, 2001. French


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Submitted on : Sunday, March 6, 2011 - 10:05:38 PM
Last modification on : Monday, March 7, 2011 - 11:44:04 AM

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Thomas Monnier. Ondes de Lamb dans les milieux stratifiés : application à la surveillance in situ et en temps réel de l'endommagement de structures composites. Mechanics [physics.med-ph]. INSA de Lyon, 2001. French. <tel-00573987>

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