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Caractérisation in-situ et modélisation des mécanismes et couplages thermomécaniques en usinage : application à l’alliage de titane Ti-6Al-4V

Abstract : This work develops an experimental and numerical strategy in order to investigate material removal of titanium alloy Ti-6Al-4V during machining process. It therefore intends to tackle a complex and strongly coupled problem, involving thermal and mechanical aspects at small scales (micrometric). The lack of measuring means dedicated to such scales in terms of time and space (rapid and strongly local phenomena) does not allow yet to precisely apprehend the thermomechanical phenomena involved during the chip formation. As a result, a specific device, called VISIR, that addresses this issue has been set-up. The experimental aspect of this work has therefore been oriented towards a more precise understanding of the material removal mechanisms. It allowed to observe the evolution of mechanical and thermal quantities during the chip formation and more precisely the strong coupling between the temperature and the strain rate. Based on these experimental insights, the thermomechanical behavior of this alloy has been studied through dynamic shear tests using hat-shaped specimens. It allowed to identify through inverse method a new constitutive equation coupled in temperature and strain rate. In addition, a study on damage is conducted. It is based on the identification and the evaluation of eight criteria commonly used in the material forming process. This leads to proposing a new damage equation, inspired from the Tresca criterion and coupled to material plastic behavior. All of these formulations along with a Stick-Slip friction model have finally been implemented in a 3D FE orthogonal cutting model. Experimental/numerical comparison in terms of mechanical and thermal quantities revealed the robustness and predictive aspect of the developed FE model. Finally, the results of this study allowed to develop a detailed discussion on the material removal mechanisms and more particularly the complexe cracks paths.
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https://tel.archives-ouvertes.fr/tel-01861377
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Submitted on : Friday, August 24, 2018 - 2:20:36 PM
Last modification on : Saturday, August 15, 2020 - 4:38:41 AM
Long-term archiving on: : Sunday, November 25, 2018 - 2:20:36 PM

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  • HAL Id : tel-01861377, version 1

Citation

Mahmoud Harzallah. Caractérisation in-situ et modélisation des mécanismes et couplages thermomécaniques en usinage : application à l’alliage de titane Ti-6Al-4V. Matériaux. Ecole des Mines d'Albi-Carmaux, 2018. Français. ⟨NNT : 2018EMAC0002⟩. ⟨tel-01861377⟩

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