Teses / dissertações sobre o tema "Soudage par transmission laser"
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Jabeen, Rowshni. "Laser transmission welding of natural fibre reinforced thermoplastic composites". Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2022. http://www.theses.fr/2022MTLD0011.
Laser transmission welding of thermoplastics requires the optimisation of interfacial adhesion at the weld joint. In this regard, the process modelling, and the development of numerical simulation tools are indispensable to optimize the mechanical strength of the weld joint. The task is more difficult in the case of highly heterogeneous and anisotropic composite materials. Moreover, the laser transmission is still difficult in the case of opaque or semi-transparent media such as natural fibre reinforced thermoplastic composites. The thermal and optical properties of composites depend on the properties and morphology of the constituents such as fibres and polymer, which can affect the transmission spectrum in the infrared range. The absorption and refraction of laser ray propagation in the composite materials lead to a reduction of the transmitted energy arriving at the weld interface, which directly influences the quality of the weld and its mechanical performance. In this dissertation, the effect of absorption and diffusion phenomena on the development of temperature field at the weld interface is analysed numerically and experimentally. Considering the fibre orientation, shape, length and volume fraction, numerical 3D geometries representing composite materials are generated to simulate the propagation of laser rays with “Ray tracing” algorithm. Numerical models to estimate the strength of weld are presented while considering the influence of welding parameters (such as laser power, feeding speed and focus position), material properties and molecular interdiffusion at the weld interface. The weld bonding strength is measured by mechanical tests and their results are compared with numerical modelling results
Rivière, Cécile. "Assemblage de céramiques par faisceau laser". Lyon, INSA, 1996. http://www.theses.fr/1996ISAL0135.
CO2 and YAG lasers were used for welging SiO2 Al2O3 ceramic tubes with 60 wt% alumina content (mullite) and Al2O3 tubes with 95wt% alumina content. Investigations of thermal stresses, which must be minimized for crack free welding, show the necessity of preheating. One can preheat the whole workpiece or part of it using different preheating methods. The welding method which could fit the two ceramics was the use of two sub-beams (one is used for preheating) obtained from the division of a primary gaussian beam. The effects of welding parameters on the microstructure of the fusion zone have been studied. Prevention of weld defects including crack and porosity was also investigated. Strength of the weld joints is evaluated by a 4-point bend test and the effects of heterogeneity of ceramics have been taken into account by a Weibull analysis. From cathodoluminescence experiments, the radiative of the samples have been probed in the wavelength rang 250-900 nm. They have been related to the presence of defects as impurities, oxygen vacancies and device centers. At last, ceramics charging properties have been tackled by the use of an original method: the mirror method
Rodriguez-Pena, Luis. "Assemblage aluminium : Acier par faisceau laser Nd : YAG". Ecully, Ecole centrale de Lyon, 2005. http://bibli.ec-lyon.fr/exl-doc/lrodriguezpena.pdf.
The reduction of consumption of fuel of internal combustion motors, imposed by the new anti-pollution and energy saving laws may be attained by reducing the weight of vehicles, introducing, for example, aluminium sections into the main steel car-body. Laser brazing is a process which can be used to perform such a junction. The main problem of welding this kind of combination of materials with conventional processes is the potential formation of inter-metallic phases, which reduces the good performance of the joint. Laser brazing allows a very good control of the thermal development of the joint, with a limited precipitation of these brittle phases. This work presents the results of a feasibility study made with ZnAl-30 and AlSi-12 as filler metal. The study shows that the type of configuration used for the assembly has a particular influence on the formation of brittle phases and consequently on the mechanical performance of the joint
Rodriguez-Pena, Luis Langlade Cécile. "Assemblage aluminium Acier par faisceau laser Nd : YAG /". [S.l.] : [s.n.], 2005. http://bibli.ec-lyon.fr/exl-doc/lrodriguezpena.pdf.
Darcourt, Claudie. "Simulation numérique du soudage laser de structures aéronautiques". Compiègne, 2005. http://www.theses.fr/2005COMP1554.
The objectif of this work is to use numerical simulation to predict residual distortions of fuselage panels. A local/global method is proposed in order to answer to this problem of large thin stuctures modelisation (with T-jonctions). It consists, in a first lime, in carrying a non-linear thermo-mechanical analysis on a 3D local mode!. An equivalent local shell model is built inssuring there are the same distorsions as the 3D model one. The global structure response is then given by copying the stress fields from the equivalent local shell model to the global shell model and by the workpiece elastic equilibrium. Each step of this method has been validated by experimental welding tests. The global structure represents a welded panel with three stiffeners. The comparison of the residual curvature between simulation and experiement gives very good results
Lê, Thi Thuy Trang. "Dimensionnement à la fatigue des structures soudées par laser". Palaiseau, Ecole polytechnique, 2009. https://pastel.archives-ouvertes.fr/pastel-00005282.
Dumord, Evelyne. "Modélisation du soudage continu par faisceau de haute énergie : application au cas du soudage par laser Nd:YAG d'un acier X5 Cr.Ni 18-10". Dijon, 1996. http://www.theses.fr/1996DIJOS056.
Iordache, Luminita. "Analyse tribo-métallurgique des rechargements base cobalt par fusion soudage d'outillages à chaud". Paris, ENSAM, 2006. http://www.theses.fr/2006ENAM0065.
Caillibotte, Georges. "Etude expérimentale de la refusion superficielle des métaux par laser CO2 multikilowatts continu". Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX22095.
Oumarou, Mairagouna Mamane. "Approche probabiliste du comportement mécanique des composites thermoplastiques assemblés par soudage laser". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00819162.
Sakout, Abdallah. "Etude théorique et expérimentale du soudage par laser : modélisation des transferts thermiques". Lyon 1, 1987. http://www.theses.fr/1987LYO19028.
Goebels, Dominique. "Amélioration du procédé de soudage laser par mise en forme du faisceau". Université Louis Pasteur (Strasbourg) (1971-2008), 2004. http://www.theses.fr/2004STR13010.
This study presents a study of the improvement of laser welding of metal thin sheets used in the automotive industry using an adapted power distribution at the focal point. The concerned materials are galvanized steel and aluminum alloy sheets, which are welded in a lap joint configuration using a continuous wave Nd:YAG laser. The difficulties of this kind of materials are due to instabilities of the welding process characterized by pores and ejections generation. First of all, we determined and quantified the influence of parameters such as depth of penetration, depth of focalization, welding speed, keyhole elongation, keyhole opening, distribution of laser power and thickness of the sheets on process stability and bead quality. The good obtained results are explained with the help of an observation campaign which permitted a better understanding of the physical phenomena. During the experiments, we found out that in Nd:YAG laser welding of thin sheets, full penetration is essential. But for zinc-coated steel sheets, it is not enough : as zinc vapors prefer escaping downward, full penetration must guaranty a sufficiently large lower aperture of the capillary, so that vapors can escape through easily. It is primordial to prevent closures of the capillary tip, due to melt pool ebb. In Nd:YAG laser welding, it is not necessary to weld with a very long focal spot to obtain good seams without ejections. This result is impossible in CO2 laser welding. Contrariwise, if the power density decreases due to a too much elongated focal spot, quality will decrease too
Sakout, Abdallah. "Etude théorique et expérimentale du soudage par laser modélisation des transferts thermiques /". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37609626w.
NAVA, RUDIGER ENRIQUE. "Contribution du controle de l'interaction laser - matiere a l'amelioration de la qualite en soudage par laser". Paris, ENSAM, 1997. http://www.theses.fr/1997ENAM0016.
Akué, Asseko André Chateau. "Modélisation du procédé de soudage laser des composites thermoplastiques". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10066.
The composite forming uses technologies being used for the simpler thermoplastic parts forming as thermoforming or welding. This thesis proposed study of transmission laser welding process in unidirectional thermoplastic composites. Transmission Laser Welding technique presents specific advantages for industrial applications over other conventional technologies: the method is accurate, flexible, small heat affected zone, easy to automate and control and non-contaminant, absence of vibration during the welding process (contrary to the ultrasonic welding, friction welding), fast welding speed for welding plastic parts with an acceptable welding time. Transmission Laser Welding of composites involves two joining parts: one semi-transparent to the laser wavelength and the other part is absorbent in the same wavelength. The two parts are positioned together before the welding. The laser beam energy is transmitted through the semi-transparent material and is absorbed within the surface of the second materials. The bonding between the two components the two parts allows the heating of the semi-transparent part by thermal conduction. Thus, melting and fusion of the both materials interface occurs (the bonding between the two parts occurs when T > Tmelt in this area). However, some difficulties are experienced during this process: heterogeneous and anisotropic materials; problems of the laser beam transfer caused by the multiplication of fiber-matrix interfaces in materials. This is highly correlated to the energy arriving at the welding interface. Obtaining of a good quality of welded seam is conditioned by a good understand of material behavior under laser irradiation, based on a clear identification, modeling of optical and thermal phenomena involved
Cretteur, Laurent. "Etude du soudage des alliages d'aluminium par laser co#2 de forte puissance". Nantes, 1998. http://www.theses.fr/1998NANT2094.
WALLEE, OLIVIER. "Contribution a l'etude du soudage d'alliages d'aluminium par faisceau laser avec fil d'apport". Université Louis Pasteur (Strasbourg) (1971-2008), 2000. http://www.theses.fr/2000STR13087.
Hamadou, Mohammed. "Étude et amélioration du processus de soudage laser par le contrôle de la méthode d'apport du gaz d'assistance". Paris, CNAM, 2003. http://www.theses.fr/2003CNAM0475.
The present study relates to the laser beam material welding. The objectives were to understand the influence of the shielding gas and its experimental set-up on the welding process in order to determine the choice of these two parameters to improve the weld bead quality according to the operating conditions. We approached in this report, the study of various effects : the effect of assist gas nature on the laser material interaction, according to the wavelength of the laser, the effect of geometrical parameters and position of the nozzle on the weld bead oxidation, the very large interest of using a high speed front assist gas flow, the importance of the groove geometry for the welding of high material thicknesses, as well as the energy distribution role for ND:Yag multispots welding
Carrer, Eric. "Etude expérimentale de l'influence d'une couverture gazeuse sur les plasmas créés lors du soudage par laser". Aix-Marseille 2, 1986. http://www.theses.fr/1986AIX22011.
Lacroix, David. "Etude spectroscopique des plasmas de soudage laser : application au transfert d'énergie". Nancy 1, 1997. http://docnum.univ-lorraine.fr/public/SCD_T_1997_0210_LACROIX.pdf.
The work presented here gives the characteristics of the laser induced-plasma plume created during laser welding. First, in the experimental part of the study, we have used the emission spectroscopy to determinate the electron temperature and the density of the plasma. Several tests have been achieved. We have estimated the influence of welding parameters such as : the laser power, the nature of the shielding gas, the pulse duration. These measurements have been achieved on stainless steel, but also on pure metals (Fe, Cr, Ni, Mo, Nb). The emission spectroscopy is used to analyse the welding defects, in order to achieve real time control of the process. Experiments have shown that geometrical and chemical (grease) defectiveness can be detected. The second part of this work is devoted to the numerical model used to describe the laser-plasma interaction. Several models are presented. The calculation of the partition function of each element of the plasma plume allows the theoretical determination of the densities. Then we can estimate the optical properties of the plume (absorption coefficient and refractive index). Electron microscopy measurements of the plasma plume deposits show the presence of sma1l particles. Consequently, we apply the Mie's theory in arder to study the laser beam scattering in the plume. Finally, we model the radiative transfer in the plasma using a discrete ordinate scheme. The numerical results point out the major effect of the scattering on the temperature field in the plume. This model can be used in complement of those calculating the geometry of the weld seam
Fontana, de Paris Aleir. "Assemblage de céramiques du type oxyde par faisceau laser". Lyon, INSA, 1992. http://www.theses.fr/1992ISAL0089.
A CO2 laser beam was used to welding oxide ceramic tubes (alumina, zircon, mullite). To prevent weld cracking a preheating process with radiant energy produced by halogen lamps and collected by reflectors was used. Several evaluation techniques like helium checking, Vickers indentation and flexural resistance were emplyed to study weld-zone characteristics
Sierra, Guillaume. "Etude métallurgique et mécanique de l'assemblage hétérogène acier/aluminium par les procédés laser et TIG". Montpellier 2, 2006. http://www.theses.fr/2006MON20228.
Diot. "Mesure de défauts dans les soudures laser sur tôle mince par ultrasons lasers et analyse par Time-Reversal". Rennes, INSA, 2012. http://www.theses.fr/2012ISAR0013.
Embedded welding defects, such as porosity, cracks, are generally formed during laser welding of aluminium. It is complicated to measure these defects with current NDI techniques. This work features the feasibility study for NDI techniques to detect such defects in lap-welded sheets of 5754 aluminium alloys, while taking into account accessibility and robustness in industrial conditions. The contact-less technique of laser ultrasound has finally been chosen. The generated sound wave is propagated into the material, it interacts with the embedded defects and therefore reports related data. The inspected material was lap-welded with a YAG laser. The use of signal processing is carried out to localise and size the defects, by means of a spring-mass simulation using FDTD. This simulation performs the reverse propagation of the sound wave, using Time-Reversal capabilities and so focuses the energy back on defects, therefore allowing an easier interpretation of ultrasound diagrams
Commin, Loreleï. "Assemblage des alliages de magnesium laminés à chaud par soudage friction malaxage et soudage laser : approche expérimentale vers une compréhension des propriétés mécaniques". Paris, ENSAM, 2008. https://pastel.archives-ouvertes.fr/pastel-00004253.
The challenges of weight reduction in aerospace industry have drawn considerable interest in magnesium alloys technologies. Assessing the efficiency of new joining techniques, such as Laser Beam Welding and Friction Stir Welding is then required. The aim of this study is to investigate the relationship between welding parameters and the resulting microstructure and mechanical properties. It was part of the AEROMAG European Project whose objective was the use of wrought Magnesium alloys in aeronautics. Friction Stir Welds and Laser Beam (Nd:YAG and CO2) Welds were processed using 2 mm thick hot rolled plates of AZ31, AZ61 and WE43 Magnesium alloys. The process window for LBW and FSW was determined. The weld characterisation was focused on AZ31 alloy. A relationship between welding parameters, the temperatures undergone and the weld microstructure was established for each process. FSW induced microstructural changes and complex residual stress distribution, which have a primary influence in FSW mechanical properties. The influence of texture evolution and precipitation evolution on LBW mechanical properties was also determined. Localisation features similar to shear bands were observed in both LBW and FSW. FSW resulted in a dramatic loss in mechanical properties, which could not be recovered after heat treatments, whereas LBW presented after heat treatment mechanical properties similar to those of the base metal. A comparison was made with precipitation hardenened alloys (AZ61 and WE43) mechanical properties. Finally, the potentiality of replacing aluminium alloys with these magnesium alloys was studied
Charton, Stephane. "Contribution à l'étude du contrôle en ligne des opérations de soudage par laser ND : Yag impulsionnel". Dijon, 1999. http://www.theses.fr/1999DIJOS047.
Carrer, Eric. "Etude expérimentale de l'influence d'une couverture gazeuse sur les plasmas créés lors du soudage par laser". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37596506z.
Girard, Karen. "Etude de la création de défauts volumiques générés pendant la solidification de soudures réalisées par faisceau laser Nd : YAG impulsionnel - application au soudage du tantale". Dijon, 1999. http://www.theses.fr/1999DIJOS067.
Bendaoud, Issam. "Contribution à la compréhension du soudage laser hybride : approche source équivalente et approche phénoménologique". Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS077.
The present study is dedicated to hybrid laser/MIG welding of high thickness steels for two different configurations: one hybrid single pass welding of superduplex steel UR2507Cu with Y-shaped chamfer geometry and a multipass hybrid welding of ferritic steel 18MND5 in narrow gap. An experimental study was carried for understanding and investigation of mechanisms governed by the process and validation of numerical models results (characterization of the weld pool and thermocouples measurements). A parametric research allows the determination of the optimal welding parameters for the Y-shaped chamfer configuration. The numerical study aims to determine the thermal history in the solid part of the work piece. Those numerical simulations which are based on two different approaches were developed using the COMSOL Multiphysics software. The first, called equivalent heat sources approach, consists only in the resolution of the heat transfer problem, and the second one, is based on the resolution of heat transfer and fluid flow problem in the weld pool by taking into account the natural convection and thermocapillarity effect. A numerical exploratory designs method is used to identify the equivalent heat sources parameters as well as some unknown parameters such as the thermophysical properties of the metal liquid and the thermal efficiency involved in the thermohydraulic models. The comparative analysis between experimental and numerical results, which permits judging the models quality to reproduce the melted zone size and shape and to validate the assumptions choice, has provided satisfying results
Chaussé, Fabrice. "Etudes expérimentale et par simulation du comportement d’un acier laminé thermomécaniquement lors du soudage hybride laser-arc monocathode et bicathodes". Nantes, 2015. https://archive.bu.univ-nantes.fr/pollux/show/show?id=ae9c15e1-4428-4daf-b761-bf38d2855acd.
Hybrid Laser-GMA welding is commercially competitive for a couple of years due to recent improvements in laser technology. It is now possible to weld thick plates in a single pass and improve the welding speed compared to conventional welding processes. After years of research and development, current technological and scientific questions are about the quality of hybrid welds in advanced materials and process optimization. S460ML is a thermomechanically controlled process steel which strength is given by a fine-grained microstructure of ferrite and pearlite. Thanks to its low carbon content, it has a low tendency to cold cracking but its microstructure and mechanical properties can be highly impacted by welding operations. Hybrid Laser- GMA welding is a good candidate to weld high strength steels with a fine microstructure as it reduces the heat affected zone (HAZ) in comparison with high productivity processes such as submerged arc welding. This work investigates the consequences of hybrid laser-MAG process with one and two MAG torches on the macrostructure, the microstructure and the mechanical properties of fully penetrated welds produced on 10 mm S460ML steel plates. The “dropping” defect which is the creation of metal drops at the root of the weld and its impact on welds quality are also analyzed. A simple numerical model is developed to calculate the temperature cycle in the material during GMAW and hybrid laser-GMA welding
Taibi, Amar. "Etude de l'influence des paramètres de soudage par laser CO2 continu sur l’émission spectrale et temporelle du plasma de soudage. : Application a l'acier inoxydable 304L, le titane Ti40 et l'aluminium". Lyon, INSA, 1993. http://www.theses.fr/1993ISAL0094.
This study deals with the plasma behaviour which a ears above the material during c. WC02 hi h power laser welding. The effects of welding parameters (power, focus point position, welding speed, gas flow) on spectral emission are analysed, as function of radiation wave length and time. The studied materials are : stainless steel 304L, titanium Ti40, and aluminium. We have showed a different behaviour of the emissions coming from the argon gas, from the emissions coming from the alloy. It appears, these emissions can be used to qualify the welding joint
Rasmussen, Dany. "Étude sur la fissuration à chaud de l'alliage 6061 lors du soudage par procédé hybride laser-GMAW /". Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2008. http://theses.uqac.ca.
La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ingénierie. CaQQUQ Comprend des réf. bibliogr. (f. [172]-176). Publié aussi en version électronique. CaQQUQ
Chen, Qing Hua. "Optimisation des caractéristiques métallurgiques et géométriques des zones superficielles de pièces traitees par laser : modélisations et étude expérimentale". Lyon, INSA, 1995. http://www.theses.fr/1995ISAL0082.
[In order to control the characteristics of the transformation hardened zone induced by laser beams at the surface of ferrous alloys, the objective of the present study is to set up a modeling technique to predict the induced effects and to select the trial parameters. We have performed a very complete bibliographical analysis of the different approaches essentially thermal ones) and drawn out three types of models: analytical models, pure numerical models and semi-phenomenological models. We have concluded that it is necessary to conduct parallelly all the three types of models to reach our objectives. The reasons are the followings: 1. The comparison among the different models, if possible, allows to verify their effectiveness and that of relating softwares developed in the study. 2. The semi- phenomenological model is indispensable to obtain the important mean thermo-physical parameters which can be injected into other models. 3. The analytical models can be used in the simple situations and give a rapid response to certain problems. 4. The numerical models using finite differences method permit us to treat many complex situations (laser beams transformed by the optical devices treatment of· rides of pieces etc. . . ). All our theoretical approaches have been supported by the relating experiments proving their correctness and effectiveness. These experiments also reveal the interests of a "ceramic" absorbent material. ]
Mayer, Cécile. "Optimisation du soudage bord-à-bord par faisceau Laser CO2 de tôles d'alliages Al-Mg : étude de la microstructure et du comportement mécanique des soudures". Lyon, INSA, 1996. http://www.theses.fr/1996ISAL0139.
The laser is a high density power source which offers new possibilities in joining technics, especially in welding of materials with poor weldability, like aluminum alloys. This work deals with the study of butt-welded sheets of alloys 5182 (4. 5% Mg) and 5754 (3% Mg), 1. 5 mm thick, with a CO2 laser. We consider several aspects: process optimization, microstructural and mechanical properties of the welds. Optimized welding conditions were determined in taking account of all the difficulties related to welding of aluminum - which results of its physical and chemical properties. We finally obtained poor defects welds (in terms of porosities and geometrical defects). The welded sheets resulting from this optimized conditions have almost the same mechanical properties as the base material. They exhibit good formability and fatigue properties. It was shown that the seam itself is more resistant than the base material in an annealed state. This can be caused by the fine dendritic microstructure with interdendritic segregations, and by the intermetallic particles refinement and spatial redistribution which take place in the welded zone. Monitoring of plasma light-emission with photodiodes offers a way to adapt laser welding to industrial process. It revealed to be useful in many welds defects detection, and in determination of laser beam to material interaction type (keyhole mode or not). So we can expect, plasma emission analysis can become a real-time control mean, in the not yet controlled process of laser welding
Gstalter, Marion. "Assemblage de verre sur verre par impulsions laser femtosecondes". Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD037.
This PhD thesis is about glass bonding by femtosecond laser pulses. A femtosecond laser source generating high repetition rate laser pulses has been used to weld borosilicate glass plates with high surface quality. The method presented in this work differs from the literature by the focusing system implemented. The influence of the laser parameters on the bonded samples performances has been studied implementing a design of experiments, demonstrating that the mechanical and thermal resistance of the samples can be improved by increasing the amount of deposited. Thebonded samples provide high mechanical resistance, higher than 25 MPa, can held high thermal shock above 300 °C and present high transparency above 90 %. Glass bonding with a distance between the glass plates has been performed by adapting the laser parameters. Bonding of glass on silicon has also been performed successfully
Tirand, Guillaume. "Etude des conditions de soudage laser d'alliages à base aluminium par voie expérimentale et à l'aide d'une simulation numérique". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14482/document.
The development of laser welding in various branches of industry particularly in the aeronautics during the last decade, required many studies still insufficient in number to understand and control the conditions of laser welding concerning laser / material interaction,as well as thermal transfers or metallurgical aspects. The approach followed in this study consists (1) to bring to light experimentally the problem of laser welding of aluminium based alloy, that is the coupling of the effects between the various welding parameters, (2) to describe the thermal history of an operation of laser welding from a modelling and from a numerical simulation and (3) to exploit the knowledge of the thermal evolution of an assembly all along welding operation to optimize the mechanical performance of the assembly in term of static resistance, resistance to hot cracking, fatigue and corrosion resistance. The deficit of performance for example in term of tensile resistance is mainly related to too low speeds of cooling during welding compared with quenching. It justifies the efficiency of a post welding solution heat treatment before a precipitation hardening treatment
Seang, Chansopheak. "Evaluation numérique des contraintes résiduelles appliquée à l'acier DP600 soudé par laser de haute puissance Nd : YAG". Phd thesis, INSA de Rennes, 2013. http://tel.archives-ouvertes.fr/tel-00875121.
Kolegain, Komlan. "Correction de trajectoires d'un robot manipulateur utilisé pour le soudage par friction malaxage". Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0033/document.
Friction Stir Welding (FSW) is a recent process used for welding metallic parts in aerospace, automotive, and railway industries. Serial industrial robots may be used as FSW welding machines, but because of their lack of stiffness, they undergo elastic deformation under the effect of stresses produced by the process. This causes a welding tool path deviation both in position and orientation, which induces defects in the weld seam. In this work, two path correction methods were developed. The first method is based on the prediction of the position and orientation deviations in the cartesian space from robot models and stiffness model of the links and the joints. The knowledge of tool deviations enabled the synthesis of a path programming approach adapted for robotic FSW. Unlike linear interpolation methods often used, this approach is based on approximations of the adapted path by Bézier or B-splines curves. Experimental validations on a Kuka KR500-2MT robot welding complex paths showed an average residual deviation of 0.3 mm and weld seams without defects. The path accuracy achieved makes it possible to consider an industrial exploitation of the developed solution. The second proposed correction method uses position feedback with a 2D laser profile sensor in the feedback loop for real-time measurement of deviations. Two controllers were designed to correct the deviations. In spite of the external disturbances related to the constraints of the process, experimental results obtained on straight and curvilinear welding paths showed the stability of the feedback loop and a mean residual deviation of 0.1 mm was achieved. The interests and difficulties of deploying this second method were also highlighted
Ferdinand, Cyrille. "Mise en oeuvre et caractérisation d'assemblages soudés par procédés TIG et laser de tôles d'alliages de titane réfractaires". Phd thesis, Toulouse, INPT, 2005. http://oatao.univ-toulouse.fr/7474/1/ferdinand1.pdf.
Courapied, Damien. "Etude de l’interaction laser matière en régime de confinement par eau avec deux impulsions laser. Application au test d’adhérence par choc laser". Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0073/document.
The laser shock wave generation is a novel process becoming more and more common. The shock waves are used to generate mechanicals effects in the sample. The laser absorption results in the creation of a plasma at the surface. This plasma during its expansion creates a shock wave propagating through the sample. This work aims to study the various phenomena involved in the laser-matter interaction. In the field of laser generated shock waves, two different processes exist: the Laser Shock Peening (LSP) and the LASer Adhesion Technique (LASAT). The new challenge deals with the limitations of those processes and the solutions to be setting up to improve them. Some ideas concerning the confinement improvement as water substitution or thermal coatings optimization are suggested in this work. Moreover, the use of double delayed laser pulses allows, for LASAT, the location of main tensile stresses near interfaces. However, for LSP, some aspects dealing with the profitability linked to the peening rate are investigated here. Last but not least, whether the very short (0 to 1000 ns) or very long delays (from 200µs to 200ms), the study of the laser-matter interaction phenomena allows to overcome some limitations for both laser shock processes
KIELWASSER, MATHIEU. "Soudage par faisceau laser de toles revetues analyse des processus physiques et des conditions de mise en uvre de solutions". Université Louis Pasteur (Strasbourg) (1971-2008), 1999. http://www.theses.fr/1999STR13239.
Robert, Yannick. "Simulation numérique du soudage du TA6V par laser YAG impulsionnel : caractérisation expérimentale et modélisation des aspects thermomécanique associés à ce procédé". Paris, ENMP, 2007. http://www.theses.fr/2007ENMP1467.
This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitation…) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. In this study, we focus on the identification of the different phase transformations occurring during the welding, during the heating and the cooling. Then we define the conditions for which the mechanical behavior of these different phases has to be characterized in order to obtain the residual stresses and the residual strains of this welded part. A thermometallurgical and mechanical modelling will thus be proposed for the YAG pulse laser welding of TA6V. The behavior of material after laser welding can be described by three fundamental data (field of temperature, metallurgical state and fields of stress/strain). We have identified and modelled the different phenomena and several stages are to be considered : Determination of the metallurgical phase transformations during the deposit of energy and the cooling ; Experimental Characterization of the mechanical behavior of each phase under the purposeful conditions of temperatures and strains ; Modeling of the thermomechanical behavior by a thermo-elasto-viscoplastic law integrating phase transformation, in order to quantify the strains and the residual stresses observed in the assemblies ; Validation of the model with a welding instrumented test
Julan, Emricka. "Simulation numérique du choc laser pour la mise en compression en présence de l'état initial dû au soudage". Palaiseau, Ecole polytechnique, 2014. https://theses.hal.science/tel-01111205/document.
Surface treatments as laser shock peening offer the possibility to reduce tensile stresses or to generate compressive stresses in order to prevent crack initiation or reduce crack growth rate in particular in the areas where tension weld residual stresses are present. Laser shock peening may be applied on different metallic components to prevent stress corrosion cracking of Inconel 600 and high cycle thermal fatigue of austenitic stainless steels. The main aim of the PhD thesis is to develop the numerical simulation of laser peening. In the first section, axisymetrical and 3D numerical models for one or several pulses have been developped in Code_Aster and Europlexus softwares. These models were validated by experimental tests carried out in PIMM-ENSAM laboratory. Parameters identification of Johnson-Cook constitutive law was carried out for Inconel 600 at high strain rates. Moreover a new test was proposed which allowed proving the isotropic behavior of Inconel 600 at high strain rates. A modification of the Johnson-Cook constitutive law was also proposed, to take into account in a new way the sensitivity of the law to high strain rates. The second section of the thesis concerns a study on the effect of an initial state of welding on residual stresses after application of laser peening. We could conclude that this initial state has no strong influence on final residual stresses. Finally, a qualitative study on the effect of strain hardening induced by laser peening on fatigue life of stainless steels was undertaken, which shows the advantage of laser peening on shot peening due to smaller strain hardening created by laser peening
Kamotesov, Sergkei. "Transmission d’énergie par induction électromagnétique en plastronique 3D". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1353.
The objective of this thesis is to evaluate the interest of 3D molded interconnect devices technologies 3D-MID for wireless power transfer (WPT) through electromagnetic induction. WPT systems mostly uses planar coils that allows transfer between receiver and emitter at low and mid-range distance, at the condition that they are well aligned. We studied a specific case with a 3D receiver enclosed in a half meter box with 4 emitting inductors on 4 sides. Three questions were examined: the magnetic resonance of 3D-MID inductors at 6.78 MHz, their dimensions and their 3D shape. The nearly spherical shape 3D-MID receiver (Ø 8 cm) was 3D printed, activated with laser direct structuring (LDS), autocatalytic metallization and electroplating. It has 3 solenoid receiving inductors, each with quality factor above 129 ±10, placed orthogonally on the equators. The experimental results show: (1) the receiver is able to receive 4.33 W at 15.8 % efficiency in the middle of the box and (2) that we can change position and orientation of the receiver in the box, the placement of the inductors allows, in a widely meaning, to mean the received power. In conclusion 3D-MID allows to integrate, relatively easily, inductors for WPT, in the casing of electronics devices, in the same way as for 3D-MID electromagnetic antennas in smartphones. These inductors can 3D-shape the casing, which will allow the design of omnidirectional receivers
Tkachenko, Iuliia. "Contribution à la compréhension et à la modélisation des phénomènes physiques se produisant lors d'un assemblage par procédé hybride laser-arc". Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS012.
An investigation on hybrid welding physics is presented in the current work. A literature review describes main physical processes occurring during Laser-arc combination and shows main achievements and problematics met during process analysis. Physical processes were studied during joining of very thick materials. Two configurations were used. The first configuration is welding of Superduplex steel in one pass by Laser and arc that are far apart. The second configuration is multipass welding of 18MND5 steel, where defocused Laser beam intercepts arc plasma. With a help of experiment’s design, fast video imaging, electric signals recording, determination of temperature and workpiece distortion, were explained the role of each thermal source and influence of their combination on arc behaviour, molten pool creation, metallic drop transfer evaluation and heat distribution into welded plates. The relationships between electric signals and arc geometry, bath dimensions and heat distribution have been analyzed at various time scales. Thermal analysis, presented in this work, shows that hypothesis of stationarity, which is commonly used in numerical modelling, is true only during a short welding period and for a given weld length. Macrographic analysis shows effect of input parameters variation on weld’s structure and geometry
POUEYO-VERWAERDE, ANNE. "Etude des processus physiques du soudage de cibles metalliques par un laser co2 continu de puissance : interaction laser-plasma et couplage thermique en regime de capillaire profond". Paris 11, 1994. http://www.theses.fr/1994PA112241.
Robert, Yannick. "Simulation numérique du soudage du TA6V par laser YAG impulsionnel : caractérisation expérimentale et modélisation des aspects thermomécaniques associés à ce procédé". Phd thesis, École Nationale Supérieure des Mines de Paris, 2007. http://pastel.archives-ouvertes.fr/pastel-00003117.
Hamie, Abbas. "Étude des régimes thermohydrodynamiques du procédé d'oxycoupage assisté par laser". Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0064/document.
Oxygen-assisted laser cutting is a widely used processed. It is well-known for its high efficiency in both the cutting speed and quality. Nonetheless, this technique requires highly secured closed environments. Currently, the dismantling industry sees this process as a way to replace more traditional cutting techniques such as blowtorches or pliers. However, to be used in such fields, the security setup needs to be less constraining, hence the energy source power is limited. This study aims at efficiently reducing the energy requirements through a better understanding of thermodynamics phenomenon as well as a deeper comprehension of the physical phenomenon driving the process. This work showed that the combustion can be initiated in solid phase and the temperature of the liquid phase during cutting process is about 2150K
Sarre, Benjamin. "Influence du soudage laser Nd˸YAG sur les propriétés métallurgiques et mécaniques de l'alliage de titane TA6V". Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0019.
Welding operation consists of assembling two or more pieces to ensure the continuity of a structure. The resulting assembly may withstand mechanical loads. However, the welding operation modifies the state of materials. In other words, the metallurgical and mechanical behaviour of the latter is deeply affected. This work aims to better understand the influence of welding on the metallurgical and mechanical behavior of the Ti-6Al-4V titanium alloy. Comprehensive metallurgical analyses of the welded joint are carried out and reveal a sharp and strong microstructure gradient between the fusion zone and the base metal. Several residual stress fields are quantified by X-ray diffraction analyzes. Those residual stress fields are then compared with finite element simulations of the welding of a Ti-6Al-4V titanium alloy. The simulation are based on a weakly coupled model that accounts for temperature, stresses and phase transformations. The failure behaviour of the welded joint is studied. An overmatch was highlighted with mechanical tests. The fracture finally occurs in the base metal despite the presence of defects in the fusion zone. A Gurson-Tvergaard-Needleman approach is carried on. The mechanical parameters are quantified from mechanical tests on homogeneous samples of base metal and of a representative microstructure of the welded joint, which has been obtained from heat treatments. The model are in good agreement with mechanical tests
Lu, Jian. "Mesure de la distribution des contraintes résiduelles par la méthode du trou incrémentale". Compiègne, 1986. http://www.theses.fr/1986COMPD045.
Relave, Sébastien. "Caractérisation et prédiction de la microstructure obtenue par fabrication additive. Application aux aciers inoxydables". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEM003.
The laser beam melting (LBM) is an additive manufacturing process that allows the production of complex samples trough a layer-by-layer melting of the powder bed by the laser beam. In the most of the studies, the solidification mechanisms were not studied in details. However, from scientific and practical point of view, it is necessary to study and to describe these mechanisms which can help to optimize the mechanical properties of LBM samples. The purposes of this study were to analyse the influence of process parameters and the powder chemical composition on the microstructure of manufactured parts and to develop a numerical simulation model capable to predict the microstructure of the part after material solidification. In this work, the microstructure and mechanical properties of 316L alloy LBM samples were analysed in dependence on the process parameters and the chemical composition of the powders. The results obtained during the study showed the significant influence of the chemical composition of the powder on the sample microstructure for the same process parameters. It was found that the chemical composition impacts the solidification path of the alloy, the latter can give different microstructure and therefore different mechanical properties. Meanwhile, thanks to thermal model developed, the solidification structure and the shape and size of the melting pool have been identified, according to the process parameters used for the experiment part. Finally, the link between the microstructure observed and the microstructure predicted by the model have been settled, leading to a deeper understanding of the solidification mechanism encountered during the LBM process