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Croissance lente de fissures: de la fragilité à la complexité

Abstract : The aim of this thesis is to contribute to the understanding of the physical mechanisms in action during the phenomenon of slow crack growth under stress. This work contains mainly experimental studies, but also theoretical ones treated analytically and numerically. We study different aspects of the phenomenon of slow crack growth starting from physical systems that appear to be the simplest and moving to more and more complex systems. We first present an analytical study of the influence of the structural disorder of a brittle elastic material on the phenomenon of thermally activated crack growth under stress. We show that disorder slows down, and even stops completely, the growth of the crack when thermodynamical temperature is under a critical value associated to it. Then, we present a detailed experimental study of the slow growth of a crack in an amorphous polymer film, namely polycarbonate. We understand the dynamics of crack growth thanks to the visco-elasto-plastic properties of the material and in particular the Arrhenius-Eyring creep law. More precisely, we show that the growth velocity of the crack can be decomposed in a term dependant on the mean stress inside the crack tip plastic zones and a term analog to a brittle rupture process. Additionally, we discover a surface instability inside the necking plastic zones of the polymer. Finally, we describe a preliminary experimental study of the peeling of an adhesive tape using a fast imaging technique. This study allows for the first time a direct access to the details of the so called stick-slip dynamics of the peeling point and opens the way for further theoretical understanding of this phenomenon.
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https://tel.archives-ouvertes.fr/tel-00162873
Contributor : Pierre-Philippe Cortet <>
Submitted on : Monday, July 16, 2007 - 12:45:49 PM
Last modification on : Wednesday, November 4, 2020 - 9:40:04 PM
Long-term archiving on: : Thursday, April 8, 2010 - 11:18:24 PM

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  • HAL Id : tel-00162873, version 1

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Pierre-Philippe Cortet. Croissance lente de fissures: de la fragilité à la complexité. Physique [physics]. Ecole normale supérieure de lyon - ENS LYON, 2007. Français. ⟨tel-00162873⟩

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