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Nouveaux modèles de comportement élasto-viscoplastique pour des matériaux métalliques. Application au dimensionnement de structures automobiles.

Abstract : Our main goal was to propose new macroscopic models in order to describe the elasto-viscoplastic behavior of metallic materials on a wide range of temperature and strain. Indeed, in an industrial point of view, the design of hot components such as exhaust manifolds for Diesel engine should be quick and predictive. Behavior laws play an important part in the design process as loads multiaxiality and anisothermal environment lead to a major impact of viscosity. Even if the choice of spheroidal graphite cast-iron is mainly motivated for such structure for reasons of cost or weight, this material is quite complex and presents a very viscoplastic behavior from 500°C. Exhaust manifold are subjected to two main design constraints: avoid crack initiation and avoid gas leakages due to inelastic strain concentration. Two models, combined with brand new experimental strategy have been proposed. Cyclic hardening tests and progressive straining tests enabled us to observe the alloy behavior on a wide range of strain, strain rate and temperature. These two macroscopic models, whose equations are based on physical phenomena observed at the dislocation scale, are thus able to cope with the various load conditions tested and to correctly described anisothermal evolution. FEM simulations confirm the good results obtained for the experimental basis and one can obtain more accurate results than those given by more traditional laws. A very good correlation is obtained between the simulations and the engine bench tests. Finally, the proposed models combined with enriched experimental database give a better representation of the viscoplasticity of cast-iron for very acceptable numerical cost.
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https://pastel.archives-ouvertes.fr/pastel-00004111
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Submitted on : Thursday, July 22, 2010 - 10:11:32 AM
Last modification on : Wednesday, October 14, 2020 - 3:52:48 AM
Long-term archiving on: : Monday, October 25, 2010 - 11:11:14 AM

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  • HAL Id : pastel-00004111, version 1

Citation

Fabien Szmytka. Nouveaux modèles de comportement élasto-viscoplastique pour des matériaux métalliques. Application au dimensionnement de structures automobiles.. Sciences de l'ingénieur [physics]. Ecole Polytechnique X, 2007. Français. ⟨pastel-00004111⟩

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