L’usinage des pièces en alliages de titane, notamment en Ti6Al4V qui a une faible usinabilité, a été toujours parmi les préoccupations majeures des entreprises du secteur de l’aéronautique. Toutefois, il est difficile, en se basant seulement à des essais expérimentaux, de bien comprendre les mécanismes participants à la formation du copeau. Il est alors nécessaire d’avoir recours à des modélisations numériques fiables permettant d’avoir accès à des grandeurs physiques instantanées et très localisées. Le travail présenté porte sur la fiabilisation de la modélisation de la coupe. Des simulations numériques 2D et 3D ont été mises en place. Le modèle de comportement de Johnson-Cook et le critère énergétique d’évolution d’endommagement ont été utilisés. L’étude préliminaire 2D de l’effet du maillage, notamment la taille, le type et la fonction d’interpolation des éléments finis, a souligné l’importance d’une discrétisation convenable du modèle qui tient compte du coût de calculs. De plus, il a été montré qu’un choix convenable du type de la formulation est crucial. L’effet des coefficients rhéologiques et d’endommagement (initiation et évolution) sur la formation du copeau (morphologie, champ de déformation et de température) a été déterminé. Des essais expérimentaux de la coupe orthogonale du Ti6Al4V à différentes conditions de coupe ont été effectués. La dépendance de la géométrie du copeau et des efforts à la vitesse de coupe et à l’avance a été étudiée. Les résultats expérimentaux ont été utilisés pour la validation des modèles numériques 3D qui permettent une étude fine de la formation du copeau. Cette approche a permis de reproduire fidèlement les phénomènes physiques se produisant au niveau du plan médian de la pièce tout en tenant compte de l’écoulement de la matière sur les bords. Les résultats prédits ont mis en évidence que, même dans le cas d’une coupe orthogonale, la formation du copeau est bien un phénomène 3D. Afin d’augmenter la fiabilité des modèles numériques 3D, une nouvelle loi thermo-viscoplastique a été proposée. Cette loi, identifiée et implémentée dans le logiciel Abaqus® à travers la routine VUMAT©, a été utilisée pour la simulation de l’usinage du Ti6Al4V. Elle a conduit à une amélioration notable des résultats numériques. / Machining of titanium alloys workpieces, especially in Ti6Al4V which has a low machinability, has always been among the major preoccupations of the companies in the aeronautics sector. However, it is difficult, basing only on experimental tests, to well understand the mechanisms involved during the chip formation. In fact, the use of reliable numerical models that allow the access to instantaneous and very localized physical quantities is required. The presented work consists on the increase of the cutting modeling reliability. 2D and 3D numerical simulations have been performed. The Johnson-Cook constitutive model and the damage evolution criterion have been used. The preliminary 2D study focused on the mesh effect, especially the size of the finite element, its type and its interpolation function, has highlighted the importance of a convenient discretization of the model that takes into account the machining computing cost. In addition, it has been shown that a suitable choice of the formulation type is crucial. The effect of the rheological and damage (initiation and evolution) coefficients on the chip formation (morphology, strain and temperature field) has been determined. Experimental orthogonal cutting tests of the Ti6Al4V at different cutting conditions have been performed. The dependency of the chip geometry and the efforts to the cutting speed and the feed rate has been studied. Experimental results have been used in the validation of the 3D numerical models, which allow a deep study of the chip formation process. This approach has allowed an accurately reproduction of the physical phenomena that occurs in the median plan of the workpiece as well as in its sides. The predicted results have highlighted that, even in the case of orthogonal cutting process, the chip formation is a 3D phenomenon. In order to increase the reliability of 3D numerical models, a new thermo-visco-plastic law has been proposed. This law, identified and implemented in the software Abqus® through the subroutine VUMAT©, has been used to model machining process of the Ti6Al4V. It has resulted in a notable improvement of numerical results.

Depuis une dizaine d’années, l’essor des minivis d’ancrage orthodontique a été grandissant jusqu’à devenir, aujourd’hui, un outil incontournable dans l’arsenal thérapeutique de l’orthodontiste. Très peu d’études ont été publiées quant à la nature de la réponse tissulaire face à l’insertion et la mise en charge de ces minivis. De plus, une partie des patients concernés par l’orthodontie étant des adolescents, il serait intéressant de savoir si le tissu osseux en croissance est propice à l’utilisation de ces dispositifs. L’influence de la nature du matériau sur cette réaction tissulaire reste également à définir. L’objectif de cette étude a été d’évaluer la biointégration de deux systèmes de minivis orthodontiques présents sur le marché, l’un en acier chirurgical et l’autre en titane-aluminium-vanadium, en conduisant une analyse clinique, histomorphométrique et microtomographique chez le porc en croissance. Les résultats ont montré que la réponse osseuse se caractérise, dans un os en croissance peu compact, par un épaississement des travées osseuses au contact des dispositifs, probablement pour résister à la contrainte locale. Le tissu osseux en croissance permet la biointégration des minivis d’ancrage orthodontique, mais le taux de succès relativement faible observé implique l’adaptation des protocoles cliniques par une analyse préalable du ratio os trabéculaire/os cortical, une augmentation du délai avant mise en charge, et l’application de forces légères. La réponse tissulaire est similaire, quel que soit le système étudié. L’acier chirurgical, grandement utilisé en orthopédie, présente donc un intérêt en orthopédie dento-faciale, dans une indication temporaire / The miniscrew implants are increasingly used over the last decade in orthodontics and gradually replacing the use of extraoral forces because of their greater efficiency and because their effectiveness is not subject to patient compliance. Few studies seeking to understand the response to orthodontic anchorage devices at bone-tissue interface have been published over the last ten years. Despite the large use of miniscrews in teenagers, very few have included young subjects in their protocol. Furthermore, despite the use of stainless steel miniscrew implants, no studies have investigated biointegration of such devices. The aim of the present study was to evaluate tissue response to immediately loaded miniscrew implants (of Ti6Al4V and of stainless steel) in growing pigs in order to answer to the following questions: Is it possible to implant and load miniscrew implants in a growing bone? Does stainless steel devices present the same biointegration than titanium devices? A clinical evaluation, and histomorphometrical and micro-CT analyses were performed. Results showed that the growing bone seems compatible with the orthodontic anchorage. In the growing pig with low bone density areas, the trabecular thickness increase appears as the bone response to withstand the local strains induced by loaded orthodontic miniscrews. Stainless steel devices presented similar behavior to the Ti6Al4V devices in pigs. This study showed the possibility to place stainless steel miniscrew implants for orthodontic anchorage in growing models

I detta   projekt har en studie av krympning vid additiv tillverkning i materialet   Ti6Al4V gjorts, detta för att analysera hur utskrifter i olika storlekar och   riktningar påverkas. Arbetet har genomförts av två studenter vid   Mittuniversitetet i Östersund och görs på uppdrag av universitetets   forskningssida. I projektet har förstudier gjorts för att lägga en grund för   arbetet. Under förstudierna hittades information om att krympningen kunde   minskas med hjälp av att använda stödmaterial i utskrifterna. Design för de   detaljer som ska skrivas ut har valts ut med hjälp av tidigare forskning där   trappor varit rekommenderat för att lätt kunna avgöra vad som händer i olika   delar av en utskrift. Även detaljer för mätning av vassa kanter och   avrundningar skrevs ut för att kunna kontrollera dessa om tid blev över men   dessa mättes aldrig då fokus under hela detta arbetet legat på trapporna.   Trapporna skrevs ut i tre olika storlekar. De skrevs ut både med och utan   stöd och i både liggande och stående led i en EBM-maskin, Arcam S12. När de   blivit utskrivna mättes de med hjälp av mikroskopet “Dino-Light edge Digital   Microscope”. Informationen som kommit fram ur dessa mätningar har sedan lagts   in i ett Excel dokument där tabeller och grafer tagits fram för att göra det   lätt att uppfatta tendenser. De utmärkande tendenser som upptäcktes var att   en större krympning alltid inträffade vid det första och tredje steget i en   utskrift. Detta inträffade oavsett vilken storlek av trappor som   kontrollerades och kunde undvikas med hjälp av att använda stödmaterial. I   modellerna med stödmaterial kunde inte speciella tendenser synas och den   krympning som syns i dessa mätningar kan bero på fel från den mänskliga   faktorn vid mätningen. Trenderna är tydliga i de detaljer som skrivits ut   utan stödmaterial. Detta fenomen kan bero på att materialet i skrivplattan   som finns i skrivaren inte är detsamma som Ti6Al4V, vilket kan ha en inverkan   på det utskrivna materialet i de lagren som är närmast skrivplattan. Krymp i   detaljerna beror också på att pulvret i skrivaren blir mindre då det smälter   vilket gör att varje lager inte får förväntad/ önskad tjocklek. Detta är ett   problem som följer med genom hela utskriften oavsett om stödmaterial används   eller ej. Arbetet som gjorts anses lyckat. / This project is a about studying and anylazing shrinkage during the   use of a EBM-machine in the material Ti6A14V. The study is done to anaylze   how prints of diffrent size and printing direction are affected by the   shrinkage. The project is done by two students at Mid Sweden University in   Östersund and the project is requested by the research department of the   university. Research has been made before the start of the project to give   the students a solid understanding in the matter. During the research for   information it was found that the shrink could be minimized by using   supportmaterial in the print. The design for the parts that was going to be   printed have been chosen through earlier studies of the matter where stairs   was recommended to easy be able to see what goes on in the different parts of   a print. Some details was also created so that measurements considering sharp   edges and round details could be checked for deformations if there was enough   time. Those were never measured since all the time of this project was   focused around the stairs. The stairs were printed in three different sizes.   They were also printed with and without supportmaterial and both standing up   and lying down in the printer EBM Arcam S12. When the parts had been printed   they were measured with a microscope called “Dino-Light edge Digital   Microscope”. The information gotten from these measurements were put into a   Microsoft Excel document where tables and graphs were created to make it easy   to spot the tendencies of the prints. The tendencies that were noticeable was   that the first and third step of every print had more shrink than the others.   This occurred no matter the size the stairs were but did not occur in the   parts printed with supportmaterial. No tendencies were noticed in the prints   with supportmaterial and the shrinkage that was noted in these prints might   also be because of the human factor. The trends are clearly visible in the   parts printed without supportmaterial. This might be because of the different   material in the printing plate that is stainless steel instead of Ti6Al4V.   This might cause problem for the layers that are printed closest to the   plate. The reason for shrinking in the details is also because of the fact   that the powder that is being printed gets melted and therefor shrinks. This   results in a thicker layer of powder everytime the powder is applied to the   printing surface. This is a problem that goes on throughout the whole print   no matter if supportmaterial is used or not. The work completed is considered to be well done. / <p>Betyg: 180809</p>

Made available in DSpace on 2016-12-08T17:19:20Z (GMT). No. of bitstreams: 1 0- Capa.pdf: 52849 bytes, checksum: 052f0059aa665dd6426fbaf7c75b0a07 (MD5) Previous issue date: 2005-12-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this dissertation is to study the friction focusing in the forces and energies needed to initiate the movement and keep it. The surfaces textures role is analyzed in roughness, r.m.s slope and fractal dimension of the surfaces profiles. This study showed that the surface profile r.m.s. slope is the main parameter to obtain the fraction coefficient figures. This study showed that it is essential to qualify the contact before to proceed with the quantitative calculation. The best parameter found to qualify the contact behavior is the Mikic plasticity index, which is compounded by the r.m.s. slope, the reduced elasticity modulus and the Vickers hardness of the materials in contact. It were prepared Ti6Al4V samples with three textures: sand blasting, shoot pinning and polished in order to verify the role of the textures regarding friction. A half of the samples were treated via plasma carbonitriding where surfaces free of micro cracks and with a relevant gain on the surface hardness were obtained. All the textures combinations were tested regarding their friction coefficients before and after the treatment. The treated samples shown similar or lightly high friction coefficients than the non treated samples, however after the friction test it was noticed that the treated samples presented less wear than the non treated samples. / O objetivo desta dissertação é estudar o atrito com foco nas forças e energias necessárias para iniciar o movimento e mantê-lo. A influência das texturas das superfícies em contato no coeficiente de atrito é analisada em rugosidade, inclinação média e dimensão fractal dos perfis das superfícies. O estudo mostrou que a inclinação média dos perfis das superfícies é o principal parâmetro relacionado ao coeficiente de atrito. O estudo mostra que é essencial qualificar o contato antes de proceder aos cálculos do coeficiente de atrito. O parâmetro que se mostrou eficiente para qualificar o regime de deformação do contato é o índice de plasticidade de Mikic, o qual é formado pela inclinação média e duas propriedades dos materiais: módulo de elasticidade reduzido e as durezas Vickers. Foram preparadas amostras de Ti6Al4V com texturas polidas, jateadas e jateadas com esferas de aço (shoot pinning) para verificar a influência da geometria das superfícies em contato no coeficiente de atrito. Metade das amostras foram carbonitretadas por plasma onde se obteve superfícies sem trincas e com ganho significativo na dureza de superfície. Todas as combinações de textura foram testadas em relação ao coeficiente de atrito antes e depois do tratamento. As amostras tratadas apresentaram coeficiente de atrito similar ou ligeiramente maior que as não tratadas, porém após os testes observou-se que as amostras tratadas apresentaram menor desgaste.

The physical and mechanical characteristics of carbon fiber reinforced polymers (CFRP) and Ti6Al4V make them widely used in the aerospace industry. The hybrid structure of CFRP/ Ti6Al4V material has been used in the new generation of aircraft manufacturing. The drilling process of these materials is often associated with unfavorable machining defects such as delamination, burr formation, reduced surface integrity, and tensile residual stresses. These machining defects are attributed to high thermal load, continuous chip morphology, and poor chips evacuation efficiency. Vibration-assisted drilling (VAD) uses an intermittent cutting process to control the uncut chip thickness and chip morphology. VAD has potential advantages include low thermal load, high chips evacuation effectiveness, and longer tool life. This thesis presents an experimental investigation into the effect of VAD machining parameters on the cutting energy, CFRP delamination, surface integrity, geometrical geometry, Ti6Al4V burr formation, induced residual stresses, and tool wear during the drilling process of CFRP, Ti6Al4V, and CFRP/Ti6Al4V stacked materials. Moreover, a kinematics model is developed to link the observed results to the independent machining parameters (i.e., cutting speed, feed rate, modulation amplitude, and modulation frequency). The experimental work covers a wide range of machining parameters using four levels of frequencies (83.3, 125, 1500, and 2150 Hz). The VAD results show up to 56 % reduction in the cutting temperature with a significant enhancement in the CFRP entry and exit delamination, geometrical accuracy, surface integrity, and burr formation. The use of VAD also generates compressive stresses, hence improving the part fatigue life. / Thesis / Doctor of Philosophy (PhD)

Les technologies de fabrication additive(FA) basées sur la technique de fusion laser sur lit de poudres, telles que les procédés de fusion sélective laser (Selective Laser Melting ‘SLM’) et de fusion par faisceau d'électrons (Electron Beam Melting ‘EBM’), ne cessent de se développer afin de produire des pièces fonctionnelles principalement dans les domaines aérospatial et médical. Le procédé de fabrication additive offre de nombreux avantages, tels que la liberté de conception, la réduction des étapes de fabrication, la réduction de la matière utilisée, et la réduction de l'empreinte carbone lors de la fabrication d'un composant. Néanmoins, les pièces obtenues nécessitent une opération d’usinage de finition afin de satisfaire les tolérances dimensionnelles et l’état de surface. / Additive Manufacturing (AM) techniques based on powder bed fusion like Selective Laser Melting(SLM) and Electron Beam Melting processes(EBM) are being developed to make fully functional parts mainly in aerospace and medical sectors. There are several advantages of using AM processes like design freedom, reduced process steps, minimal material usage and reduced carbon footprint while producing a component. Nevertheless, the parts are built with near net shape and then finish machined to meet the demands of surface quality and dimensional tolerance.

In the present study, production of titanium and Ti6Al4V alloy foams has been investigated using powder metallurgical space holder technique in which magnesium powder were utilized to generate porosities in the range 30 to 90 vol. %. Also, sintering of titanium and Ti-6Al-4V alloy powders in loose and compacted condition at various temperatures (850-1250oC) and compaction pressures (120-1125 MPa), respectively, were investigated to elucidate the structure and mechanical properties of the porous cell walls present due to partial sintering of powders in the specimens prepared by space holder technique. In addition, microstructure and mechanical response of the porous alloys were compared with the furnace cooled bulk samples of Ti-6Al-4V-ELI alloy subsequent to betatizing. It has been observed that the magnesium also acts as a deoxidizer during foaming experiments, and its content and removal temperature is critical in determining the sample collapse. Stress-strain curves of the foams exhibited a linear elastic region / a long plateau stage / and a densification stage. Whereas, curves of loose powder sintered samples were similar to that of bulk alloy. Shearing failure in foam samples occurred as series of deformation bands formed in the direction normal to the applied load and cell collapsing occured in discrete bands. Average neck size of samples sintered in loose or compacted condition were found to be different even when they had the same porosity, and the strength was observed to change linearly with the square of neck size ratio. The relation between mechanical properties of the foam and its relative density, which is calculated considering the micro porous cell wall, was observed to obey power law. The proportionality constant and the exponent reflect the structure and properties of cell walls and edges and macro pore character.

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Thesis (MScEng (Industrial Engineering))--Stellenbosch University, 2008. / There is a growing global demand for titanium. The aircraft industry is the driving force behind the demand for titanium. The reason for this is that titanium has attractive properties that justify its use both economically and environmentally. Titanium alloys have superior strength-to-weight ratios. This implies that by substituting components manufactured from other metals in the aircraft with titanium components, a substantial reduction in structural weight can be achieved. From an economical point of view a lower mass implies lower fuel consumption. From an environmental point of view lower fuel consumption implies less harmful greenhouse emissions. Ti6Al4V components are the most widely used titanium alloy products in aircraft components. Ti6Al4V is known as a difficult-to-machine material. This is due to its low thermal conductivity and small contact area between the tool and the chips causing higher temperatures to be generated closer to the cutting edge of the insert. This will subsequently increase the rate at which the cutting tool wears. For this reason relatively low cutting speeds and feed rates are employed for the machining of Ti6Al4V compared to the machining of steels. Ti6Al4V is an exceptionally high cost material. The low cutting speeds and feed rates used in Ti6Al4V machining raises the machining cost of parts and contributes to an increase in the price of Ti6Al4V parts. By employing higher cutting speeds and feed rates machining times on Ti6Al4V products could be decreased, subsequently lowering the price for Ti6Al4V components. An increase in cutting speeds and feed rates will subsequently cause an increase in generated cutting temperatures, resulting in an increase in tool wear. This stresses the importance of controlling the cutting temperature during machining of Ti6Al4V in order to prolong tool life. The focus of this work was to investigate different lubrication strategies for polycrystalline diamond (PCD) and tungsten carbide inserts for Ti6Al4V milling operations in the quest to develop improved feasible cutting parameters. The results of this study showed that flood lubrication should be utilized for PCD inserts, while a “softer” 60 bar high pressure through spindle lubrication worked best for the tungsten carbide inserts. By utilizing these lubrication strategies, cutting speeds of 100 m/min and feeds per tooth of 0.05 mm/rev for both the PCD and tungsten carbide grades could be attained with satisfactory tool life.

Le but de cette étude était de simuler par éléments finis la mise en forme à froid à et à chaud d'alliages de titane. Les alliages de titane ont une microstructure et un comportement complexes qui évoluent en fonction de la température, de la déformation, mais aussi de la vitesse de déformation, il est donc difficile de déterminer une loi de comportement fiable sur une large plage de sollicitations. Le choix d'une loi de comportement macroscopique élasto-viscoplastique thermodépendante est donc nécessaire pour représenter le procédé de formage à chaud dans une plage de température pertinente. Différentes lois de comportement répondaient aux besoins du projet, mais la loi de comportement d’Adinel Gavrus est la plus appropriée. Les résultats ont mis en évidence le fait que les alliages de titane TA6V et Ti6242 sont anisotropes à haute température et que l’anisotropie à chaud du TA6V et du Ti6242 peut être représentée à l’aide du critère de plasticité Hill48. Afin de déterminer le comportement mais aussi l’anisotropie du matériau, l’éprouvette doit être visible lors des essais de traction afin d’utiliser la corrélation d’image pour obtenir les champs de déformation locaux et ainsi obtenir l’évolution des coefficients d’anisotropie au cours de l’essai. Le procédé de chauffage par effet joule a été utilisé, la machine de traction a exigé de multiples modifications afin d’être isolée électriquement. Le chauffage par effet joule est finalement une solution efficace pour effectuer des essais de tractions à chaud tout en visualisant l’éprouvette. L’analyse inverse a permis d’utiliser les données d’entrée des essais de traction afin d’identifier les différents paramètres de la loi de comportement développée par Adinel Gavrus. D’autre part, la corrélation d’image couplée aux essais de traction a permis l’obtention des valeurs du critère d’anisotropie plastique de Hill48. La mesure des coefficients d’anisotropie a mis en exergue le fait que le critère de Hill48 était pertinent pour la modélisation du TA6V ainsi que du Ti6242 à haute température. La mise en forme du godet à fond plat ainsi que des pièces industrielles a permis d’avoir des cas concrets de mise en forme ainsi que d’identifier les problèmes récurrents dans la mise en forme de produits minces à chaud comme à froid. La modélisation de ces différents essais a été réalisée sous le logiciel FORGE®, la corrélation d’image 3D a pu être utilisée sur le cas de l’emboutissage à froid de godet à fond plat afin de comparer les valeurs de déformation. Néanmoins la corrélation d’image 3D n’est pas utilisable sur les cas d’emboutissage à chaud. Il a donc fallu utiliser un autre observable. Nous avons choisi pour cela la distribution d’épaisseur le long de différents profils de chaque pièce. Les résultats obtenus sont très positifs mettant en avant la pertinence de la simulation numérique. Nous avons ensuite étudié l’optimisation des processus de formage suivant différents angles. L’optimisation manuelle de la géométrie fut pertinente, à l’aide d’une modification simple de la géométrie initiale du flan, le procédé de formage a pu être réalisé en une passe au lieu de deux. L’analyse de sensibilité des paramètres de la loi de comportement a permis de mettre en avant l’importance des coefficients de la loi de comportement en plus de leurs impacts sur l’épaisseur minimale lors d’un essai d’emboutissage. La corrélation entre essai de traction et épaisseur minimale sur l’essai d’emboutissage n’a pas donné les résultats escomptés, les données d’entrée utilisées suite aux essais de traction n’étaient certainement pas suffisantes pour être corrélées à l’épaisseur minimale obtenue au cours d’un essai d’emboutissage. Enfin l’étude de la covariance des paramètres des lois de comportement a permis d’étudier en profondeur les surfaces de réponses issues de l’analyse inverse tout en mettant en évidence les impacts des minimums locaux et globaux lors de la minimisation de la fonction coût. / The purpose of this study was to simulate by finite element cold and hot forming in titanium alloys. Titanium alloys have a complex microstructure and behavior that change depending on the temperature, deformation, but also the strain rate, so it is difficult to determine a behavior law reliable over a wide range of loads. The choice of a macroscopic elastic-viscoplastic temperature dependent behavior law is necessary to represent the hot-forming process in a relevant temperature range. Different behavior laws met the needs of the project, but Adinel Gavrus behavior law is the most appropriate. The results showed that the titanium alloy Ti6Al4V and Ti6242 are anisotropic at high temperature and that the plasticity of Ti6Al4V and Ti6242 can be represented using the Hill48 yield criterion. To determine the behavior but also the anisotropy of the material, the specimen must be visible during tensile tests in order to use the image correlation in order to obtain local deformation fields and thus to obtain the evolution of the coefficients of anisotropy during the test. The method of heating by the Joule effect has been used, the traction machine required multiple modifications to be electrically insulated. The heating by the Joule effect is finally an effective solution for making hot tensile test while viewing the specimen. The inverse analysis allowed using the tensile test input data to identify the different parameters of the constitutive law developed by Adinel Gavrus. On the other hand, the image correlation coupled with tensile tests allowed obtaining the values of plastic anisotropy of specific Hill48. The measurement of anisotropy coefficients highlighted the fact that the test was relevant to Hill48 modeling Ti6Al4V and to the Ti6242 at high temperature. The forming of cup and industrial parts allowed having concrete cases of forming and identifying recurring problems in the hot or cold forming of thin products. Modeling these tests was carried out on the Forge® software, the 3D image correlation have been used to compare values with the case of cup drawing with cold deformation. Nevertheless the 3D image correlation was not used on the case of hot stamping. It was therefore necessary to use a different observable. We chose the thickness distribution along different profiles of each piece. The results are very positive, highlighting the relevance of numerical simulation. Then we studied the optimization of the following forming process different angles. The manual optimization of the geometry was relevant, with a simple modification of the initial geometry of the blank, the forming process could be achieved in one pass instead of two. The sensitivity analysis of the parameters of the constitutive law has helped to highlight the importance of the coefficients of the constitutive law in addition to their impact on the minimum thickness at a drawing test. The correlation between tensile test and minimum thickness on the test stamping has not yielded the expected results, the input data used following the tensile tests were certainly not sufficient to be correlated to the minimum thickness obtained during a drawing test. Finally the study of the behavior laws of covariance parameters allowed to study in depth the surface response resulting from the inverse analysis while highlighting the impacts of local and global minima during the minimization of the cost function.