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Caractérisation et modélisation du comportement et de la rupture de thermoplastiques pour une large gamme de vitesse de déformation et de température

Abstract : Nowadays, polymers are used for the interior parts of vehicles. It is particularly the case for components such as dashboards and door panels. These elements are submitted to requirements imposed by international regulations in order to minimize the injuries of the passengers in case of a car crash. It is therefore essential to characterize the mechanical properties of those polymeric materials for several load cases on a wide range of strain-rate and temperature. The collected data can be used to fill numerical behavior models supposed to accurately predict the whole behavior of a polymer, if possible up the failure, taking all polymer behavior specificities into account. Indeed, aiming at optimizing development costs, numerical simulation is currently a key tool in the design of engineering components. Thus, in this thesis work, it is proposed to characterize the complete whole behavior of a semi-crystalline polymer in a wide range of strain-rate and temperature until failure. First, some DMA and tensile tests are carried out in order to characterize the viscoelastic and viscoplastic properties of the material. Then, time-temperature-superposition principle is introduced and validated in the two domains. A model based on the constitutive equations developed by Balieu and al. and enriched thanks to this principle is identified and implemented in the Ls Dyna code. It is validated by comparison with experimental results. Secondly, the work focusses on the experimental characterization and the modelling of failure. Several specimen geometries are designed to reach some specific triaxiality ratios and are tested at different strain-rates and two temperatures +23 and -30°C. A failure behavior surface is thus identified and introduced in the GISSMO failure model. The complete model of behavior, i.e. constituted of behavior laws and failure criterion, is then validated based on comparison with experimental data extracted from tests on specimens, but also on an industrial demonstrator.
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https://hal-uphf.archives-ouvertes.fr/tel-03376760
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Submitted on : Wednesday, October 13, 2021 - 4:44:45 PM
Last modification on : Tuesday, October 19, 2021 - 4:50:34 PM

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  • HAL Id : tel-03376760, version 1

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Vincent Dorleans. Caractérisation et modélisation du comportement et de la rupture de thermoplastiques pour une large gamme de vitesse de déformation et de température. Sciences de l'ingénieur [physics]. Université Polytechnique Hauts-de-France; Institut national des sciences appliquées Hauts-de-France, 2020. Français. ⟨NNT : 2020UPHF0031⟩. ⟨tel-03376760⟩

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