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Ageing of a carbon/epoxy composite for aeronautic applications

Walid Trabelsi
Abstract : At elevated temperature, the matrix oxidation is mainly involved in the thermal degradation of carbon-epoxy composite material. Indeed an oxidized thin layer is built up at the material surface, which induces a weight loss and a mechanical behavior weakening. The aim of this work is to predict such phenomenon through a realistic model built on the interaction of the material with the surrounding atmosphere. Low thickness samples of epoxy matrix and three carbon-epoxy laminates (UD, [03/903]s and [453/-453]s) are used for experimental study. For modeling the behaviour, a kinetic model of radical chain oxidation coupled with oxygen diffusion is used. It is based on a "close-loop" oxidation mechanistic scheme and gives the theoretical concentration profile of oxidation products in the sample thickness versus the ageing time. Thicknesses of the oxidized layers and weight losses are then deduced. One of the key parameters which governs the matrix oxidation is the oxygen diffusion. It was experimentally measured at various temperatures for various epoxy matrix and UD composite. Numerical results are compared to experimental ones to check the validity of the model. A good agreement between experimental and numerical results of weight loss and oxidized layer thicknesses is obtained. The failure of composite parts exposed at elevated temperature for a long period results mostly from the thermal oxidation of the matrix. This one involves an embrittlement of the oxidized layers. Experimental study of the mechanical behavior shows a decrease of the elastic modulus and fracture properties. Toughness seems also to decrease after ageing. Cracks created on the edges can induce a total embrittlement and change drastically the mechanical behavior of the material.
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https://pastel.archives-ouvertes.fr/pastel-00002194
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Tuesday, February 20, 2007 - 8:00:00 AM
Last modification on : Tuesday, February 20, 2007 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:03:52 PM

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  • HAL Id : pastel-00002194, version 1

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Walid Trabelsi. Ageing of a carbon/epoxy composite for aeronautic applications. Engineering Sciences [physics]. Arts et Métiers ParisTech, 2006. English. ⟨NNT : 2006ENAM0064⟩. ⟨pastel-00002194⟩

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