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Durabilité des composites carbone/époxy pour applications pales d'hydroliennes

Abstract : Composite materials are used in many marine structures and new applications are being developed such as tidal turbine blades. The reliability of these components, in a very severe environment, is crucial to the profitability of tidal current energy systems. These structures are subject to many forces such as ocean tides, waves, storms but also to various marine aggressions, such as sea water and corrosion. A thorough understanding of the long term behavior of the moving parts is therefore essential. The majority of tidal turbine developers have preferred carbon blades, so there is a need to understand how long immersion in the ocean affects these composites. In this study the long term behavior of different carbon/epoxy composites has been studied using accelerated ageing tests. A significant reduction of composite strengths has been observed after saturation of the material in seawater. For longer immersions only small further changes in these properties occur. No significant changes have been observed for moduli nor for composite toughness. Changes in properties are initially due to matrix plasticization, followed by reductions due to fibre/matrix interface changes. Damage can affect the long term behavior of composites structures and create new pathways for water diffusion. As a consequence a damage model has been proposed based on a coupled strength/toughness criterion to describe the threshold of damage and on a toughness criterion to describe the crack development kinetics. It describes in a correct manner the damage threshold and kinetics for the as-received material and for material after sea water ageing. The evolution of the rate of water ingress into composite materials has been followed, in order to develop a diffusion model taking into account the anisotropic nature of composites. Then the diffusion model has been applied on a tidal turbine blade. Finally a first investigation of the coupling between the diffusion model and damage has been performed. This study has contributed to the development of tools to quantify long term durability of composite tidal turbine blades.
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Submitted on : Friday, December 21, 2018 - 10:35:07 AM
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  • HAL Id : tel-01285006, version 2

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Nicolas Tual. Durabilité des composites carbone/époxy pour applications pales d'hydroliennes. Génie mécanique [physics.class-ph]. Université de Bretagne occidentale - Brest, 2015. Français. ⟨NNT : 2015BRES0057⟩. ⟨tel-01285006v2⟩

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