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Etude de la compétition déchirure ductile / rupture fragile : Application à la tenue mécanique des tubes en acier C-Mn et de leurs joints soudés.

Abstract : This study deals with the fracture behaviour of welded thin structures in the ductile to brittle transition range. It aims to propose a criterion to define the conditions for which the risk of fracture per cleavage does not exist on a cracked structure.

The literature review shows that the difficulties of prediction of the fracture behaviour of a structure are related to the dependence of the fracture probability to the mechanical fields at the crack tip. The ductile to brittle transition range thus depends on the studied geometry of the structure.

A threshold stress, below which cleavage cannot take place, is defined using fracture tests on notched specimens broken at very low temperature.

The finite element numerical simulation of fracture tests on CT specimens in the transition range shows a linear relation between the fracture probability and the volume exceeding the threshold stress, thus showing the relevance of the proposed criterion. Moreover, several relations are established allowing to simplify the identification of the criterion parameters.

The criterion is applied to a nuclear structural C-Mn steel, by focusing more particularly on the higher boundary of the transition range. A fracture test on a full-scale pipe is designed, developed, carried out and analysed using its numerical simulation. The results show firstly that, on the structure, the transition range is shifted in temperature, compared to laboratory specimens, due to the low plasticity constraint met in thin structures, and secondly that the threshold stress criterion allows to estimate simply this shift.
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https://tel.archives-ouvertes.fr/tel-00142227
Contributor : Vincent Le Corre <>
Submitted on : Sunday, May 6, 2007 - 6:55:34 PM
Last modification on : Tuesday, November 24, 2020 - 2:18:05 PM
Long-term archiving on: : Tuesday, September 21, 2010 - 1:36:15 PM

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  • HAL Id : tel-00142227, version 2

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Vincent Le Corre. Etude de la compétition déchirure ductile / rupture fragile : Application à la tenue mécanique des tubes en acier C-Mn et de leurs joints soudés.. Mécanique [physics.med-ph]. Ecole Centrale de Lille, 2006. Français. ⟨tel-00142227v2⟩

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