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Experimental study of the behavior of colonies of environmentally-assisted short cracks by digital image correlation, acoustic emission and electrochemical noise

Abstract : This work concerns with the current needs of enhancing the tools used for predicting the remnant lifetime of structures subjected to the risk of initiation and propagation of multiple stress corrosion cracks (SCC). The approach consists in developing an original experimental methodology based on joint measurements of digital image correlation (DIC), acoustic emission (EA) and electrochemical noise (EN). The final objective is to contribute to both the understanding of the mechanisms involved in the development of interacting short stress corrosion cracks and to the modeling of the colony behavior. The choice of optimal conditions for the heat treatment of a Nickel-base alloy and for the pH of a polythionate solution allowed controlling the morphological parameters of intergranular cracks colonies, which were investigated by DIC owning to an optimized suitable surface treatment. The different propagation stages of a single crack and some colonies were identified, together with the involved mechanisms, through experiments and analyses performed in 2D and 3D. This innovative experimental approach allowed settling the basements of the numerical modeling and validating it. A particular attention was focused on EN measurements through a critical analysis of the perturbations generated by the instrumental noise and the asymmetry of the studied system. The limitations of the technique for its application to the quantitative study of SCC were evaluated on the basis of the present results. A transposal of the experimental approach towards high temperature and pressure conditions of test was finally proposed as a short-term prospect of this work, also allowing considering other modes of crack propagation linked to the material microstructure in the numerical approach.
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https://tel.archives-ouvertes.fr/tel-01940909
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Submitted on : Friday, November 30, 2018 - 3:44:24 PM
Last modification on : Wednesday, September 16, 2020 - 4:08:56 AM
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  • HAL Id : tel-01940909, version 1

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José Bolivar Vina. Experimental study of the behavior of colonies of environmentally-assisted short cracks by digital image correlation, acoustic emission and electrochemical noise. Materials. Université de Lyon, 2017. English. ⟨NNT : 2017LYSEI059⟩. ⟨tel-01940909⟩

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