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Modèle par éléments discrets multi physique du comportement des matériaux métalliques sous sollicitations thermo mécaniques extrêmes

Abstract : The work of this thesis concerns the development of a model using the discrete element method, for the thermo-mechanical behavior of an aluminum alloy and its microstructural evolution when exposed to conditions of large deformations and/or high deformation rates (Friction StirWelding or FSW). Friction stir welding is a recent welding process invented in 1991 by "The welding Institute" (TWI). This process is different from the others by its ability to weld material in the viscous state, without reaching the melting point. The principle is relatively simple and similar to a milling process except that the cutting tool is replaced by a rotary tool composed of a pin and a shoulder. This process is of great interest in the aircraft industry because it offers the possibility to weld aluminum alloys 2XXX and 7XXX series, known to be difficult to weld by other processes. Since friction stir welding is a recent process, it still remains a subject of active research, to better understand certain issues such as material flow, influence of process parameters (rotation speed, tool shape, ...) and the modification of the microstructure. This last point is particularly important for structural hardening alloys such as those of the 2XXX and 7XXX series. For these aluminum alloys, the mechanical properties are highly dependent on their state of precipitation, which is itself influenced by the heat generated during thewelding. The optimization ofwelding parameters in order to obtain good mechanical properties requires the prediction of precipitation state along thewelded joint. Thework of this thesis is to develop required models at the scale of microstructure allowing to predict the modification of material properties related to the process parameters
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  • HAL Id : tel-01827243, version 1

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Moubarak Gado. Modèle par éléments discrets multi physique du comportement des matériaux métalliques sous sollicitations thermo mécaniques extrêmes. Mécanique des matériaux [physics.class-ph]. Université de Bordeaux, 2017. Français. ⟨NNT : 2017BORD0707⟩. ⟨tel-01827243⟩

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