Interaction laser/matière en régime de perçage par percussionanalyse expérimentale, modélisation et simulation numérique

Abstract : The laser drilling process is the main process used in machining procedures on aeronautic engines, especially in the cooling parts of the engine. The industrial stake is to reduce geometrical deviations of the holes and defects during production.The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involve thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood. This thesis work is attached to give some responses to these questions with a simulation approach.An experimental investigation was first set up in order to estimate the velocity of the liquid, the vapor pressure and the temperature of the surface and to characterize the influence of the laser power and some material properties on the drilling.The physical model of the laser drilling used for simulations include solid/liquid and liquid/vapor phase transformations, the liquid ejection and the convective and conductive thermal exchanges. It is solved using a homemade calculation code and 2D axisymmetric formulation, developed during the thesis. The development is based on a recent numerical method called CNEM (Constrained Natural Element Method). This method allows us to use a lagrangian representation of the moving boundaries and the liquid flow and so facilitates the application of the boundary conditions. The model parameters were taken from literature or from measures.Simulations results predicted most of measurements without identifying any parameters. The deviations between experiments and simulations gave new discussions on the influence of the laser beam space repartition and on the contribution of the metallic vapor phase on the hole geometry. The thermal cycles were studied clarifying the metallurgical transformations induced by laser drilling.
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Submitted on : Thursday, September 25, 2014 - 12:27:15 PM
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Jérémie Girardot. Interaction laser/matière en régime de perçage par percussionanalyse expérimentale, modélisation et simulation numérique. Génie mécanique [physics.class-ph]. Ecole nationale supérieure d'arts et métiers - ENSAM, 2014. Français. ⟨NNT : 2014ENAM0001⟩. ⟨pastel-01068269⟩

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