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Simulation physique des conditions thermomécaniques de forgeage et d'usinage : caractérisation et modélisation de la rhéologie et de l'endommagement

Abstract : During forging and machining processes materials undergo significant and rapid deformations responsible for localised heating, microstructural changes and damage. The modelling of such phenomena requires an accurate knowledge of behaviour and damage laws, for a large range of strains, strain rates and temperatures. Compression tests were performed on a Gleeble thermomechanical simulator and a Split Hopkinson Pressure Bar device on two steels (42CrMo4 and 100Cr6) and an aluminium alloy (2017-T4). Three behaviour domains are identified corresponding to cold, warm and hot working. The microtructural phenomena for each domain are analysed and linked to the observed rheological behaviour. After a review of various models from the literature, a new empirical model is proposed which properly accounts for the competition between work hardening and softening. Via coupling, it reproduces the effects of temperature and strain rate. The damage mechanisms at room temperature are characterised from in situ tensile tests performed in a Scanning Electron Microscope and using the digital image correlation method. The results from tensile tests on axisymmetrically notched specimens are used to characterise the damage at various temperatures. Two damage models are described and applied: Johnson-Cook's fracture criterion and Gurson-Tvergaard-Needleman's coupled micromechanical model. Finally the various behaviour models are applied and discussed for the Finite Element simulations of orthogonal cutting, shear tests on 'hat-shaped' specimens and plane strain tests.
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https://pastel.archives-ouvertes.fr/pastel-00593068
Contributor : Anis Hor <>
Submitted on : Friday, May 13, 2011 - 11:50:27 AM
Last modification on : Friday, October 23, 2020 - 4:37:30 PM
Long-term archiving on: : Sunday, August 14, 2011 - 3:00:01 AM

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  • HAL Id : pastel-00593068, version 1

Citation

Anis Hor. Simulation physique des conditions thermomécaniques de forgeage et d'usinage : caractérisation et modélisation de la rhéologie et de l'endommagement. Mécanique des matériaux [physics.class-ph]. Arts et Métiers ParisTech, 2011. Français. ⟨NNT : 2010ENAM0002⟩. ⟨pastel-00593068⟩

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