Blassiau, Sébastien (2005) Modélisation des phénomènes microstructuraux au sein d'un composite unidirectionnel carbone/epoxy et prédiction de durée de vie: contrôle et qualification de réservoirs bobinés. PhD thesis Sciences et génie des matériaux, ENSMP - Centre des Matériaux P.M. Fourt, ENSMP.

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Abstract

A parallel has been made between the design and failure of high pressure vessels containing natural gas used as a fuel for public vehicles and that of unidirectional carbon fibre reinforced epoxy resin. Natural gas is increasingly being used as a fuel as it results in far less environmentally polluting emissions than other, oil based, and fuels. Carbon fibre reinforced epoxy resin has many characteristics which make it attractive for such an application however long term damage accumulation in it when under load is not understood in any quantitative manner. For this reason it has been seen to be important to identify the processes involved in the degradation of the composite when subjected to long term loading, both for scientific and technological reasons. Acoustic emission has been seen to be a promising means of detecting damage in composite materials and the study has been able to relate the microstructural processes of damage to the activity recorded from both laboratory specimens and composite pressure vessels through the development of detailed analytical model of the damage processes involved.

The increased calculating capacity which is now available has allowed the analytical model of failure accumulation to be related to the acoustic emission recorded during testing of carbon fibre unidirectional composites and pressure vessels in a way that has not been possible in the past.

The protocol proposed for testing carbon fibre composite pressure vessels has been validated by both experimental and theoretical studies. A multiscale model beginning at the scale of individual fibres and the surrounding matrix has been developed so as to take into account the accumulated effects of individual fibre breaks on the behaviour of the whole composite and so explain the acoustic emissions detected during the tests. This has allowed the validation of an industrial protocol for quantifying damage, accumulated in service, in pressure vessels and to predict minimum residual lifetimes for future in-service use.

Table of content

INTRODUCTION

PARTIE 1 - PROBLEMATIQUE INDUSTRIELLE ET DEMARCHE

CHAPITRE 1 - La problématique industrielle 9

CHAPITRE 2 - Généralités, vocabulaire et notations sur les matériaux composite à fibres longues et leurs endommagements 11

CHAPITRE 3 - Conception des réservoirs composites G.N.V., mode d'endommagement et proposition d'un protocole de qualification 15

CHAPITRE 4 - L'émission Acoustique 19

CHAPITRE 5 - Conclusion et démarche adoptée 31

PARTIE 2 - ETUDE EXPERIMENTALE

CHAPITRE 6 - Matériaux et procédures expérimentales 35

CHAPITRE 7 - Résultats expérimentaux 49

PARTIE 3 - MODELISATION

CHAPITRE 8 - Analyse des micromécanismes de transfert de charge au sein d'un composite à fibres longues 77

CHAPITRE 9 - Modélisation de la rupture macroscopique d'un composite unidirectionnel à 0° par un procédé multiéchelle 117

PARTIE 4 - INDUSTRIALISATION

CHAPITRE 10 - Proposition d'une méthode de contrôle et de qualification des réservoirs bobinés carbone/époxy 151

CHAPITRE 11 - Mise en pratique de la méthode de qualification de réservoirs en service sur bus 157

CONCLUSION

ANNEXES

Statistiques de consultation

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