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Influence de la microstructure sur le comportement mécanique de l'alliage de titane Ti-6Al-4V : étude expérimentale et modélisation numérique multi-échelle

Abstract : Improving the mechanical performances of materials used in aeronautics industry is generally based on the understanding of the relationships between their microstructural features and their mechanical behavior observed at the macroscopic scale. In addition, the heterogeneous and the anisotropic nature of many materials, in particular Ti-6Al-4V titanium alloy, implies a rather detailed investigation of the mechanical behavior at the local scale. This PhD work is a contribution to analyze the mechanical behavior of the Ti-6Al-4V alloy submitted to monotonic and cyclic loadings by considering relationship with the microstructure features. Microstructural characterizations were first performed on nodular Ti-6Al-4V microstructures with identical crystallographic texture and three different grain sizes (ultra fine, fine and standard), then on microstructures with the same grain size but two texturing degrees (strong texturing and weak) were assessed. In a second step, mechanical tensile and cyclic experiences were carried out. The results were used in development of a model with a macroscopic approach. Subsequently, a sliding trace analysis technique was developed in order to identify the contribution of different sliding systems on the accommodation of plastic deformation during the tensile or cyclic loadings. The final part of PhD work was dedicated to the development of a Crystal Plasticity-Finite Element model (CPFEM) to analyze the coupled effect of the average grain sizes, their relative scattering and crystallographic textures on the mechanical behavior at different scales: microscopic (sliding mechanism), mesoscopic (grains) and macroscopic scales. The model parameters were identified using appropriate techniques for the scale transitions. The Representative Volume Element (RVE) necessary for such modeling has been optimized with two constraints: a representative number of grains and an adequate meshing in terms of numbers and type of elements. The numerical simulations were performed using Abaqus/ Standard finite element calculation code interfaced by ZMAT library.
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https://tel.archives-ouvertes.fr/tel-02968559
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Submitted on : Thursday, October 15, 2020 - 9:29:15 PM
Last modification on : Monday, October 19, 2020 - 3:12:14 PM

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  • HAL Id : tel-02968559, version 1

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Fatna Benmessaoud. Influence de la microstructure sur le comportement mécanique de l'alliage de titane Ti-6Al-4V : étude expérimentale et modélisation numérique multi-échelle. Matériaux. Ecole des Mines d'Albi-Carmaux, 2020. Français. ⟨NNT : 2020EMAC0005⟩. ⟨tel-02968559⟩

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