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Modélisation de la propagation des ondes élastiques dans un milieu composite à microstructure 3D

Abstract : The simulation of nondestructive examinations is of great interest to optimize testing configurations and to help interpreting collected data. This thesis deals with the modeling of ultrasonic propagation into woven composite materials. These materials are made from Carbon fibers (micrometric) assembled into bundles (millimetric) which are woven to form a layer; their structure is thus heterogeneous at two scales. To study the material at the weave scale, one first needs to know the mechanical properties of bundles. We propose two methods aiming at dynamically homogenize the material at this scale. The first one achieves identification of complex rigidity coefficients of the effective material by comparing the wave numbers of guided waves propagating in the effective materials with those of guided waves propagating in the heterogeneous composite. A genetic algorithm is developed to match the sets of wave numbers, allowing to identify some of the coefficients. The second method extends an existing model that homogenizes bundles and takes into account multiple scattering of bulk waves on fibers. The existing model (3-phase model) was limited to waves at normal incidence; the extension deals with oblique incidence. For this, the problem of multiple scattering of waves under oblique incidence on fibers is solved; the solution takes into account the anisotropy and viscoelasticity of the various phases. A genetic algorithm (as already used in the first homogenization method) allows one to identify the complex effective rigidity coefficients. Results obtained using this method finally brings us to question some of the basic hypotheses made to proceed to dynamic homogenization.
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Submitted on : Tuesday, July 2, 2013 - 4:36:33 PM
Last modification on : Friday, August 5, 2022 - 2:54:00 PM
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  • HAL Id : tel-00840603, version 1

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Matthieu Hollette. Modélisation de la propagation des ondes élastiques dans un milieu composite à microstructure 3D. Autre. Université Sciences et Technologies - Bordeaux I, 2013. Français. ⟨NNT : 2013BOR14777⟩. ⟨tel-00840603⟩

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