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Contribution à l'étude expérimentale et numérique du comportement des tôles d'épaisseur submillimétrique

Abstract : The miniaturization demand of manufactured parts is continuously increasing. Mass production of sub-millimeter parts is made difficult by a certain number of phenomena related to the work scale. The aim of this PhD thesis is to develop an original approach allowing prediction of the mechanical response of thin sheets during the forming process. Firstly, one-dimensional tensile tests on submillimetric sheets of copper, aluminium and stainless steel are conducted. They highlight the influence of the free surface and the grain size distribution on the mechanical response of sheets. Secondly, an elasto-viscoplastic single-crystal constitutive law, formulated in large strains and taking into account the physical mechanisms of plastic deformation, is developed and implemented in the finite element code ABAQUS®. This constitutive law uses the dislocations densities as internal variables. To be functional, this approach requires a fine description of microstructural state of the simulated material. A statistical processing of real measurements is developed in order to generate a finite elements model describing in a precise way the grains morphology, their sizes and their crystallographic orientations. Then, this original methodology developed is used to reproduce the phenomena we observe in experiments, namely: · softening of the global behavior of material, · appearance of so-called orange peel, · strong strain localization in the thickness of specimen, directed perpendicular to the tensile direction. Besides, the exploitation of this numerical tool makes it possible to check influence of the free surface and the prevalence of the coarse grains on the global response of the real structures. Finally, an in situ testing machine is designed and manufactured in order to validate the numerical approach, under conditions close to those generated in micro-forming.
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https://pastel.archives-ouvertes.fr/pastel-00003738
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Monday, May 19, 2008 - 8:00:00 AM
Last modification on : Tuesday, October 20, 2020 - 3:11:12 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:38:38 PM

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  • HAL Id : pastel-00003738, version 1
  • PRODINRA : 246888

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Citation

Nicolas Bonnet. Contribution à l'étude expérimentale et numérique du comportement des tôles d'épaisseur submillimétrique. Sciences de l'ingénieur [physics]. Arts et Métiers ParisTech, 2007. Français. ⟨NNT : 2007ENAM0004⟩. ⟨pastel-00003738⟩

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