Comportement mécanique des métaux polycristallins aux grandes déformations en tosion : expériences et simulations

Abstract : The comprehension of the behaviour of materials that subjected to multiaxial loading with large deformations is very important for many analyses of technology and design. The axial strain during torsion test is an effect which can be used to verify the performance of a theoretical model. This test is also simple enough to obtain good experimental data. Torsion test is most conveniently carried out on a solid bar with circular section, however, there is a gradient in the physical quantities throughout the section of a solid bar. Axial stresses and axial strains can also develop in the torsion test. Thus, it is necessary to make a certain modelling in order to interpret the results. In this work, simulations have been carried out in free end torsion testing of solid bars in order to reproduce the Swift effect for Cu, Al, NiAl and Mg materials, for which new experimental results have also been presented. The hardening behaviour is analysed for large strains in polycrystalline copper as a function of strain rate and temperature. Special tests with variable testing speed were designed to simulate the hardening behaviour of copper that can occur in Equal Channel Angular Extrusion. Finally, we studied the phenomenon of dynamic recrystallisation in torsion of polycrystalline copper. The microstructure and the crystallographic textures were analyzed by using the EBSD method (Electron Back Scattering Diffraction).
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Fathallah Qods. Comportement mécanique des métaux polycristallins aux grandes déformations en tosion : expériences et simulations. Autre. Université Paul Verlaine - Metz, 2006. Français. ⟨NNT : 2006METZ013S⟩. ⟨tel-01752456⟩

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