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Home > Thèses et HDR > Thèses en 2019

19/06/2019 - Aurélien CHAZOTTES-LECONTE

by Laurent Krähenbühl - published on , updated on


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Aurélien Chazottes-Leconte soutient sa thèse le 19/06/2019 à 14:00.
Lieu : amphithéâtre Clémence Royer, bâtiment Jacqueline Ferrand- 12 rue des sports, 69621 Villeurbanne], 12 rue des sports 69621 Villeurbanne.

Cette thèse a été réalisée en partenariat avec le laboratoire Ampère, Mateis et le LaMCoS, sous la direction de Charles Joubert (Ampère), Thibaut Chaise (LaMCoS) et Laurent Morel (Ampère).

Conception and realization of electromagnetic pulse peening device

Jury :
- Lehmann Pascale, Chercheure, Institut Saint-Louis, rapporteure ;
- Thuillier Sandrine, Professeure, Centre de recherche C. Huygens, rapporteure ;
- Clerc Guy, Professeur, Laboratoire Ampère, Examinateur ;
- Robin Vincent, Ingénieur - Docteur, EDF R&D, Examinateur ;
- Joubert Charles, Professeur, Laboratoire Ampère ;
- Chaise Thibaut, Maître de conférences, LaMCoS, Co-Directeur ;
- Morel Laurent, Maître de conférences, Laboratoire Ampère, Invité ;
- Nélias Daniel, Professeur, LaMCoS, Invité ;
- Razik Hubert, Professeur, Laboratoire Ampère, Invité.

Abstract :
Penning processes are widely used in industries to apply compressive residual stresses into the most solicited part of mechanical pieces. In that way, the compressive residual stresses limit the priming and the propagation of micro-cracks in the material. This increases significantly the lifespan of the treated mechanical piece under fatigue stresses. These existing peening processes have proved their efficiency and also their limitations and weaknesses. The main recurrent defaults are a shallow depth of treatment, a degradation of the surface condition, a random control of the treatment, a material contamination, etc. These problems have led towards the development of news innovative peening processes which allow better performance avoiding some previous defaults briefly evoked. Among these news processes, the electromagnetic peening process seems especially interesting. This process uses high energy electromagnetic fields to induce Lorentz forces into a metallic piece and thus residual stresses. Actually, there is not much information about this process in the literature and no prototype was ever built. The work of this thesis is dedicated to development and realization of an electromagnetic peening prototype.
The first chapter of this thesis adresses the state of the art of major peening processes actually
in industrial use. Next, the electromagnetic peening process, or EMP process, is described and the electrical needs are exposed. A second state of the art is made about the technological solutions to respond to the EMP needs. The second chapter is about the conception of the EMP prototype with the electrical structure adopted in the previous chapter. The first step is about the inductor sizing to generate an electromagnetic field sufficient enough for a peening application. Next, the storage system is designed depending on the inductor parameters and finally the closing switch is created considering the electrical parameters used for the EMP process. To validate the previous results, a 3D electromagnetic simulation is done. The prototype assembly is presented in the third chapter and also the first experimental test on the EMP prototype. To begin with, an aluminium alloy with low yield strength is selected to be treated. Two different samples forms are used, a thin one, to realize a similar test to the Almen test and thick one to check the EMP depth of treatment. A 3D multiphysics simulation of these experiments is made and these numeric results are next correlated to the experimental ones. In the fourth chapter, an exploratory study is realized on the effects of the residual stresses on magnetic properties of ferromagnetic material, the mumetal.

Key Words : Electromagnetic peening, peening process, electromagnetic pulse generator, current pulse generator, electromagnetism, high voltage, residual stresses, magnetic materials, finite elements method.