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1
Sazerat, Marjolaine. "Fabrication additive arc-fil (WAAM) pour la réparation de composants aéronautiques en Waspaloy : caractérisation microstructurale, mécanique et vieillissement métallurgique". Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2024. http://www.theses.fr/2024ESMA0024.
Testo completoAbstract (sommario):
Le procédé de soudage Cold Metal Transfer (CMT) est envisagé comme un moyen de réparation additive pour les pièces de grandes dimensions. Cette technologie offre un taux de dépôt élevé avec un apport de chaleur réduit en raison du transfert de matière en régime de court-circuit. Son utilisation permettrait de réduire considérablement les temps d’opération liés à la maintenance, réparation et révision (MRO). Le Waspaloy, superalliage base Ni polycristallin durci par précipitation γ', est communément utilisé dans les parties chaudes des turboréacteurs. Il est, toutefois, considéré marginalement soudable en raison de sa forte teneur en aluminium et en titane. Cette particularité mène à un manque de données dans la littérature scientifique sur ce couple matériau/procédé. Ces travaux de thèse, menés à l’Institut P’ et en collaboration avec le site de MRO de Safran Aircraft Engines (Châtellerault), ont été dédiés à l’étude du Waspaloy CMT. Le premier axe d’analyse a été la caractérisation, à la fois microstructurale et mécanique, du matériau à l’état brut de fabrication. La structure granulaire et dendritique est présentée, de même que la précipitation γ' hétérogène entre les cœurs de dendrite et les espaces interdendritiques. La ségrégation chimique qui en est responsable est mise en évidence, et les propriétés mécaniques monotones, en traction et en fluage jusqu’à 850 °C, sont évaluées. Ensuite, avec l’intention d’optimiser la microstructure hétérogène par un traitement thermique post-soudage différent de celui préconisé pour le matériau forgé, un deuxième axe s’est dégagé autour de la stabilité thermique du Waspaloy CMT. Le grossissement des précipités γ' et les cinétiques de vieillissement sont approchés par la théorie de Lifshitz-Slyozov-Wagner. La formation de phases secondaires est observée, avec l’identification de carbures M23C6 par leur nature chimique et cristalline. Des diagrammes temps-température-transformation expérimentaux sont établis. La question de l’équilibre thermodynamique est abordée par l’application d’un revenu long, et numériquement par des simulations Thermo-Calc®. L’effet du traitement thermique de revenu sur le comportement en traction et en fluage est étudié, en comparaison avec le Waspaloy CMT brut de fabrication et le matériau forgé de référence. Les liens entre les propriétés obtenues et les évolutions microstructurales sont mis en lumière. L’investigation de la tenue mécanique de l’interface entre le substrat forgé et le rechargement CMT s’est également imposéeCold Metal Transfer (CMT), a wire arc welding process, is being contemplated as a means of additive repair for large aeronautical components. This technology offers a high deposition rate with reduced heat input due to short-circuit material transfer. Its use would considerably reduce maintenance, repair and overhaul (MRO) times. Waspaloy, a γ' precipitation-hardened polycrystalline Ni-based superalloy, is commonly used in the hot sections of jet engines. It is, however, considered marginally weldable due to its high aluminum and titanium content. This particularity leads to a lack of data in the scientific literature on this material/process pair. This thesis work, carried out at the Institut P' and in collaboration with the MRO center of Safran Aircraft Engines (Châtellerault), was dedicated to the study of CMT Waspaloy. The first axis of analysis was the characterization, both microstructural and mechanical, of the material in its as-built state. The granular and dendritic structure is presented, as is the heterogeneous γ' precipitation between dendrite cores and interdendritic spaces. The chemical segregation responsible for this is highlighted, and the monotonic mechanical properties up to 850°C, through both tensile and creep testing, are evaluated. Then, with the intention of optimizing the out-of-equilibrium microstructure by a post-weld heat treatment different from that recommended for the wrought material, a second focus emerged around the thermal stability of CMT Waspaloy. γ' precipitation coarsening and aging kinetics are approximated using the Lifshitz-Slyozov-Wagner theory. The formation of secondary phases is observed, with the identification of M23C6 carbides by their chemical and crystalline nature. Experimental time-temperature-transformation diagrams are established. The question of thermodynamic equilibrium is addressed through the application of a long ageing heat treatment, and numerically through Thermo-Calc® simulations. The effect of ageing on tensile and creep behavior is investigated, in comparison with as-built CMT Waspaloy and the reference wrought material. The links between the resulting properties and microstructural evolutions are highlighted. The mechanical strength of the interface between the wrought substrate and the CMT refurbishment is also investigated
2
Sequeira, Almeida P. M. "Process control and development in wire and arc additive manufacturing". Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7845.
Testo completoAbstract (sommario):
This thesis describes advancements in the modelling, optimisation, process control and mechanical performance of novel high deposition rate gas metal arc welding processes for large scale additive manufacturing applications. One of the main objectives of this study was to develop fundamental understanding of the mechanisms involved during processing with particular focus on single layer welds made of carbon steel using both pulsed-current gas metal arc welding and cold metal transfer processes. The effects of interactions between critical welding process variables and weld bead and plate fusion characteristics are studied for single and multi-layers. It was shown that several bead and plate fusion characteristics are strongly affected by the contact tip to work distance, TRIM, wire feed speed, wire feed speed to travel speed ratio, and wire diameter in pulsed-current gas metal arc welding. The arc-length control, dynamic correction and the contact tip to work distance are shown to strongly influence the weld bead geometry in the cold metal transfer process. This fundamental knowledge was essential to ensure the successful development of predictive interaction models capable of determining the weld bead geometry from the welding process parameters. The models were developed using the least-squares analysis and multiple linear regression method. The gas tungsten constricted arc welding process was utilised for the first time for out-of-chamber fabrication of a large scale and high-quality Ti-6Al-4V component. The main focus was, however, in the use of the cold metal transfer process for improving out-of-chamber deposition of Ti-6Al-4V at much higher deposition rates. The effect of the cold metal transfer process on the grain refinement features in the fusion zone of single layer welds under different torch gas shielding conditions was investigated. It was shown that significant grain refinement occurs with increasing helium content. The morphological features and static mechanical performance of the resulting multi-layered Ti-6Al-4V walls were also examined and compared with those in gas tungsten constricted arc welding. The results show that a considerable improvement in static tensile properties is obtained in both testing directions with cold metal transfer over gas tungsten constricted arc welding. It was suggested that this improvement in the mechanical behaviour could be due to the formation of more fine-grained structures,which are therefore more isotropic. The average ultimate tensile strength and yield strength of the as-deposited Ti-6Al-4V material processed via cold metal transfer meet the minima specification values recommended for most Ti-6Al-4V products. Neutron diffraction technique was used to establish the effect of repeated thermo-mechanical cycling on the generation, evolution and distribution of residual stresses during wire and arc additive manufacturing. The results show a significant redistribution of longitudinal residual stresses along both the substrate and multi-bead with repeated deposition. However, a nearly complete relaxation occurs along the built, once the base plate constraint is removed.
3
Ding, J. "Thermo-mechanical analysis of wire and arc additive manufacturing process". Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7897.
Testo completoAbstract (sommario):
Conventional manufacturing processes often require a large amount of machining and cannot satisfy the continuously increasing requirements of a sustainable, low cost, and environmentally friendly modern industry. Thus, Additive Manufacturing (AM) has become an important industrial process for the manufacture of custom-made metal workpieces. Among the different AM processes, Wire and Arc Additive Manufacture (WAAM) has the ability to manufacture large, low volume metal work-pieces due to its high deposition rate. In this process, 3D metallic components are built by depositing beads of weld metal in a layer by layer fashion. However, the non-uniform expansion and contraction of the material during the thermal cycle results in residual stresses and distortion. To obtain a better understanding of the thermo-mechanical performance of the WAAM process, a study based on FE simulation was untaken in this thesis. The mechanism of the stress generation during the deposition process was analysed via a 3D transient thermo-mechanical FE model which is verified with experimental results. To be capable of analysing the thermo-mechanical behaviour of large-scale WAAM components, an efficient FE approach was developed which can significantly reduce the computational time. The accuracy of this model was validated against the transient model as well as experimental measurements. With the help of the FE models studies on different deposition parameters, deposition sequences and deposition strategies were carried out. It has been proved that the residual stresses and the distortions are possible to be reduced by using optimised deposition parameters and sequences. In addition, a robot path generation prototype has been developed to help efficiently integrate these optimised process settings in the real-wold WAAM process.
4
Karlsson, Mattias, e Axel Magnusson. "Wire and Arc Additive Manufacturing : Pre printing strategy for torque arm". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79176.
Testo completoAbstract (sommario):
Wire and Arc Additive Manufacturing (WAAM) is a novel Additive manufacturing method. It is a high deposition rate process which can be suitable for producing low to medium quantities of medium to large sized components. Because it is such a novel method, there are still somechallenges to solve for the method to be useful. This project have been focusing on how to dealwith these challenges and how to manufacture a torque arm with WAAM. This includes the process on how to go from a CAD model to a printed product. Tests have been done during the project parallel with the design of the torque arm. The design have been modied according to the results from the tests. The result of the project was a more specic description how the softwares can be used to optimizethe process for a successful print. The used slicing software, Simplify3D, have some limitations and other options should be considered. Some limitations for the part design have been identied and some known challenges have been solved. The torque arm was successfully printed but with more time and refinement, the added offset could be reduced. The process was time consuming and needs to be more automated in the future. Some proposals on what should be further tested and evaluated is also stated in this report.
5
Jonsson, Vannucci Tomas. "Investigating the Part Programming Process for Wire and Arc Additive Manufacturing". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74291.
Testo completoAbstract (sommario):
Wire and Arc Additive Manufacturing is a novel Additive Manufacturing technology. As a result, the process for progressing from a solid model to manufacturing code, i.e. the Part Programming process, is undeveloped. In this report the Part Programming process, unique for Wire and Arc Additive Manufacturing, has been investigated to answer three questions; What is the Part Programming process for Wire and Arc Additive Manufacturing? What are the requirements on the Part Programming process? What software can be used for the Part Programming process? With a systematic review of publications on Wire and Arc Additive Manufacturing and related subjects, the steps of the Part Programming process and its requirements have been clarified. The Part Programming process has been used for evaluation of software solutions, resulting in multiple recommendations for implemented usage. Verification of assumptions, made by the systematic review, has been done by physical experiments to give further credibility to the results.
6
Graf, Marcel, Andre Hälsig, Kevin Höfer, Birgit Awiszus e Peter Mayr. "Thermo-Mechanical Modelling of Wire-Arc Additive Manufacturing (WAAM) of Semi-Finished Products". MDPI AG, 2018. https://monarch.qucosa.de/id/qucosa%3A33161.
Testo completoAbstract (sommario):
Additive manufacturing processes have been investigated for some years, and are commonly used industrially in the field of plastics for small- and medium-sized series. The use of metallic deposition material has been intensively studied on the laboratory scale, but the numerical prediction is not yet state of the art. This paper examines numerical approaches for predicting temperature fields, distortions, and mechanical properties using the Finite Element (FE) software MSC Marc. For process mapping, the filler materials G4Si1 (1.5130) for steel, and AZ31 for magnesium, were first characterized in terms of thermo-physical and thermo-mechanical properties with process-relevant cast microstructure. These material parameters are necessary for a detailed thermo-mechanical coupled Finite Element Method (FEM). The focus of the investigations was on the numerical analysis of the influence of the wire feed (2.5–5.0 m/min) and the weld path orientation (unidirectional or continuous) on the temperature evolution for multi-layered walls of miscellaneous materials. For the calibration of the numerical model, the real welding experiments were carried out using the gas-metal arc-welding process—cold metal transfer (CMT) technology. A uniform wall geometry can be produced with a continuous welding path, because a more homogeneous temperature distribution results.
7
Koskenniemi, Isak. "Preparing parts for Wire and Arc Additive Manufacturing (WAAM) and net-shape machining". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74296.
Testo completoAbstract (sommario):
WAAM is a relatively unexplored additive manufacturing method. Although research in this area has been performed for some years and the hardware is relatively cheap, the method is not widely used. As the name suggest, it uses wire and an arc welding equipment to deposit beads on top of each other to create a geometry. As WAAM is a near net-shape method, the parts must be machined to its net-shape after the beads has been deposited. BAE Systems Hägglunds AB are investigating the use of WAAM in an industrial robot cell and this Master’s thesis has been written with the purpose of enabling the use of WAAM for manufacturing parts at the company. This report investigates how a part is prepared for WAAM and near net-shape machining. A formula for approximating the cost of manufacturing a part is investigated. A software for slicing a .STL file for generating a toolpath is developed in Matlab. The software then exports the toolpath to a code that the robot can read. It can also generate a digital model of the work piece for net-shape machining through CATIA macro. A model for calculating the cost of using the WAAM-cell once the toolpath for a part is known is presented. The investigated areas and the developed software are then applied to a part, and the results of the report is discussed.
8
Machado, Duarte Jéssica. "Experimental and numerical studies on Wire-and-Arc Additively Manufactured stainless steel rods". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Cerca il testo completoAbstract (sommario):
Additive manufacturing has gained worldwide popularity due to its numerous benefits, which includes structural efficiency, reduction of material consumption and wastage, enhanced customisation, improved accuracy and safety on-site. Among the various categories of the additive manufacturing process, Wire and arc additive manufacturing (WAAM) has proven its ability of producing medium to large scale components. However, there is still a lack of knowledge regarding the structural response and mechanical properties of WAAM-produced elements. This paper provides results of numerical and experimental studies on WAAM rods produces using a commercial ER308LSi stainless steel welding wire. The aim is to evaluate the effect of initial imperfections and material mechanical properties on the response of such rods under compression. Tensile and compression tests were carried out in order to determine the mechanical properties of the rods. Subsequently, numerical simulations were performed in order to simulate the mechanical response of the rods under different conditions.
9
Chu, Jeffrey B. (Jeffrey Bowen). "Investigating the feasibility and impact of integrating wire-arc additive manufacturing in aerospace tooling applications". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/126954.
Testo completoAbstract (sommario):
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020
Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 65-67).
The use of wire-arc additive manufacturing (WAAM) as fabrication method for Iron-Nickel 36 (Invar36) alloy aerospace tooling is a growing area of interest for many tooling companies and composite aircraft manufacturers. However, the full adoption and utilization of WAAM techniques is hindered due to lack of industry experience and end-part quality precedent. For some tool makers, the feasibility of utilizing additively manufactured Invar components is still under investigation because key material characteristics of end-parts are not well understood. Further, the impact of implementing additive manufacturing on a manufacturer's internal operations is not widely documented. While much academic research has been conducted on WAAM technologies, Invar, and change management for new technology introductions, much of the available literature does not provide the specificity needed to supplant an aerospace toolmakers' need for hands-on experience. This research will investigate both the technical feasibility of using WAAM Invar components (with respect to end-part quality and performance) in aerospace tool fabrication, as well as the organizational feasibility and impact of adopting the technology. This thesis will describe the series of testing completed to evaluate WAAM Invar in the context of an aerospace toolmaker and will outline some of the key organizational impacts that must be acknowledged for adoption of additive manufacturing within an aerospace tool making company. Because of this research, we hope to demonstrate the viability of utilizing WAAM Invar for aerospace tooling applications.
by Jeffrey B. Chu.
M.B.A.
S.M.
M.B.A. Massachusetts Institute of Technology, Sloan School of Management
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
10
Arrè, Lidiana. "Design, fabrication and mechanical characterization studies on Wire and Arc Additively Manufactured (WAAM) diagrid elements". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25666/.
Testo completoAbstract (sommario):
The design approach changed in the last decades with the innovation offered by software for Computer-Aided Design (CAD), three-dimensional computer modelling and digital fabrication methods enabling new forms. The development in digital fabrication techniques led to the application of automatic processes in the structural engineering sector through Additive Manufacturing (AM) based technologies. It offers numerous benefits over conventional manufacturing methods, such as design of more complex and optimized components due to greater freedoms in shape and geometry, therefore bringing to a reduced material usage and shortened build times. The focus of this research is on the metal additive manufacturing methods, in particular, the adopted technique is the Wire-and-Arc Additive Manufacturing (WAAM), which best suits the possibility to realize large-scale metal structures and to allow new geometric forms. WAAM advantages compared to the other processes are fast large-scale production, freedoms in shape and geometry, structural efficiency with reduced material usage. The current research comprises the overarching process from the computational design to the mechanical characterization of the WAAM-produced elements, through the fabrication step. The computational design and fabrication stages were carried out at Technische Universität Braunschweig. There is still limited research focused on the characterization of WAAM-produced metal elements for structural engineering applications, therefore the research carried out at University of Bologna was focused on the establishment of 3D-outcome mechanical properties, pointing up the influence of surface roughness and imperfections on the mechanical response, together with the study on how the intersection between WAAM-produced bars influences the overall behavior of the specimen.
11
Qiu, Xundong. "Effect of rolling on fatigue crack growth rate of Wire and Arc Additive Manufacture (WAAM) processed Titanium". Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8441.
Testo completoAbstract (sommario):
Titanium (Ti) alloys have been commonly used in the aerospace industry, not
only because they have a high strength-to-weight ratio (comparing to the steels)
but also their satisfactory corrosion resistance. Furthermore, they can be
assembled with the carbon fibre composite parts. However, conventional
manufacturing methods cause high material scrap rate and require lots of
machining to obtain the final shape and size, which increases both the
manufacturing time and cost. In order to improve the efficiency and reduce the
cost of Ti parts, Additive Manufacturing (AM) has been developed.
Rolled Wire and Arc Additive Manufacturing (rolled WAAM) is one of the AM
processes. The main characteristics of this technology is the reduced β grain
size to refine the alloy's microstructure. Both the ultimate tensile strength and
yield strength of Ti alloy made by rolled WAAM are at least 10% higher than
traditional wrought Ti.
This project is to investigate the fatigue crack growth rates of the Ti-6Al-4V built
by rolled WAAM process in both the longitudinal and transverse orientations to
study the effect of rolling on fatigue crack growth rate of WAAM processed Ti.
The project was carried out by testing the fatigue crack growth rates for 4
compact tension specimens. The test results of different orientations were
compared with each other, and scatters in fatigue life and fatigue crack growth
rate were found. Fatigue crack growth rate is lower in the longitudinal
specimens. The results are also compared with those of the unrolled WAAM
specimens tested in a previous project. It was found that rolling can significantly
improve the fatigue crack growth behaviour in WAAM processed Ti, and can
reduce the difference between the two orientations, i.e. achieving better
isotropic material properties. Recorded scatters may be caused by the process
induced residual stresses, error in measurement, and the test machine load
range being much higher than the applied loads. More specimens can be tested
to validate above observations further.
12
Adebayo, Adeyinka. "Characterisation of integrated WAAM and machining processes". Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8258.
Testo completoAbstract (sommario):
This research describes the process of manufacturing and machining of wire and arc additive manufactured (WAAM) thin wall structures on integrated and non¬integrated WAAM systems. The overall aim of this thesis is to obtain a better understanding of deposition and machining of WAAM wall parts through an integrated system. This research includes the study of the comparison of deposition of WAAM wall structures on different WAAM platforms, namely an Integrated SAM Edgetek grinding machine, an ABB robot and a Friction Stir Welding (FSW) machine. The result shows that WAAM is a robustly transferable technique that can be implemented across a variety of different platforms typically available in industry. For WAAM deposition, a rise in output repeatedly involves high welding travel speed that usually leads to an undesired humping effect. As part of the objectives of this thesis was to study the travel speed limit for humping. The findings from this research show that the travel speed limit falls within a certain region at which humping starts to occur. One of the objectives of this thesis was to study the effect of lubricants during sequential and non-sequential machining/deposition of the WAAM parts. Conventional fluid lubricants and solid lubricants were used. In addition, the effect of cleaning of deposited wall samples with acetone was also studied. A systematic study shows that a significant amount of solid lubricant contamination can be found in the deposited material. Furthermore, the results indicate that even cleaning of the wire and arc additive manufactured surfaces with acetone prior to the weld deposition can affect the microstructure of the deposited material.
13
Martina, Filomeno. "Investigation of methods to manipulate geometry, microstructure and mechanical properties in titanium large scale Wire+Arc Additive Manufacturing". Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9270.
Testo completoAbstract (sommario):
Wire+arc additive manufacturing is a technique suitable for the deposition of large components; a variety of materials can be processed, including titanium. For the alloy Ti{6Al{4V, an experimental model based on design of experiment and linear regression was developed to control layer geometry during deposition. The modelled variables were wall width and layer height; the former was dependent on the heat input, and the latter on the heat input as well as on the wire feed speed to travel speed ratio. Equations enabled the automatic selection of process parameters based on geometric requirements speci c to the part being built. This could ensure minimisation of production time and material waste. Additively manufactured parts are a ected by distortion and residual stress; the e ect of high pressure rolling on these two, as well as on geometry, microstructure and mechanical properties was studied. Due to plastic deformation, rolled linear deposits were characterised by a larger width and smaller height. The variability of the layer height was reduced, a bene cial e ect from a production implementation viewpoint. Distortion was less than half in rolled components, a change associated with the reduction in residual stress which were still tensile in the bottom of the parts and compressive in their top; however their overall magnitude was smaller than in the unrolled samples. The contour method showed relatively good agreement with the neutron di raction measurements, and although destructive it proved to be a fast way to characterise residual stress in additively manufactured components. Microstructurally, the columnar prior grains con guration observed in all unrolled deposits, also a ected by a strong texture developed in the building direction, was changed to equiaxed grains due to the recrystallisation triggered by both the strain introduced by rolling and the repeated thermal cycles induced by each layer deposition. The microstructure was overall considerably ner and the texture randomised. A fundamental study was performed to discern the extent of the deformed zone from the one a ected thermally. While the deformed zone could not be identi ed precisely, the thermally in uenced zone showed a relationship between rolling load and depth of the recrystallised volume. Finally, testing of hardness and tensile strength showed superior properties of rolled specimens than in the unrolled specimens. The mechanical performance of rolled samples was fully isotropic too. This project was entirely sponsored by Airbus Group Innovations (formerly EADS Innovation Works).
14
Cornia, Luca. "Design computazionale e analisi sperimentale di pali reticolari atomizzati di nuova generazione realizzati con tecnologia Wire and Arc Additive Manufacturing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Cerca il testo completoAbstract (sommario):
La tesi ha come oggetto l’analisi computazionale e sperimentale di pali reticolari innovativi realizzati mediante la tecnologia di stampa 3D metallica riferita come Wire-and-Arc Additive Manufacturing.
Il progetto di questa tesi consiste nel design di un palo reticolare innovativo mediante software di disegno parametrico. Il palo ha una sezione tubolare “atomizzata” che forma una superficie esterna di tipo reticolare (“lattice structure”) costituita da elementi rettilinei continui. La continuità dei filamenti costituenti la struttura reticolare è garantita grazie alla tecnologia di realizzazione di tipo additivo per metalli di tipo Wire-and-Arc Additive Manufacturing che supera la richiesta di connessione di più elementi grazie alla realizzazione di un unico elemento tubolare di tipo reticolare. L’innovazione consiste nell’alta flessibilità di personalizzazione, in quanto la geometria è in grado di potersi adattare parametricamente a diverse esigenze generando un elemento ad hoc. Pluralità di ingombri, raffittimenti localizzati e sezioni di spessore variabile in altezza rendono possibili applicazioni diversificate.
La parte sperimentale della tesi mira a indagare l’elemento di intersezione delle aste che formano il palo reticolare in acciaio inossidabile stampato mediante la tecnologia Wire-and- Arc Additive Manufacturing.
Sono stati eseguiti test di laboratorio a trazione su elementi che simulano i nodi di collegamento presenti in un elemento reticolare stampato in 3D. Il fine ultimo delle sperimentazioni conseguite è l’analisi delle differenze e/o similitudini nel comportamento sotto sollecitazione meccanica dei nodi quali punti critici di un elemento strutturale.
15
Querard, Vincent. "Réalisation de pièces aéronautiques de grandes dimensions par fabrication additive WAAM". Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0001/document.
Testo completoAbstract (sommario):
Dans le domaine de la fabrication additive plusieurs technologies cohabitent et présentent des maturités et des applications différentes : le lit de poudre, la projection de poudre et le dépôt de fil pour ne citer que les principales. Nous avons étudié, dans le cadre de cette thèse, la réalisation de pièces de grandes dimensions du domaine aéronautique en alliage d’aluminium, par technologie WAAM (Wire Arc Additive Manufacturing) robotisée. Cette technologie repose sur l’utilisation un générateur de soudure à l'arc, d’un système de protection gazeuse et d’un système d'alimentation en métal d'apport sous forme de fil. Pour répondre à cette problématique, plusieurs voies de recherche ont été investiguées. La première traitait principalement de la génération de trajectoires : Plusieurs expérimentations ont permis de montrer l’intérêt et l’importance de la génération de trajectoires et notamment la maitrise de l’orientation outil pour la fabrication additive de pièces complexes en étudiant le respect de la géométrie souhaitée. La seconde concernait l’étude de la santé matière des pièces fabriquées. Des observations au niveau de la microstructure, mais aussi des caractéristiques mécaniques ont permis de mettre en évidence l’influence des paramètres opératoires sur la qualité de la matière déposée. Enfin, la réalisation de pièces fonctionnelles dans le cadre d’un projet financé par la DGA/DGAC et dont les partenaires étaient : STELIA, CONSTELLIUM, CT INGENIERIE et l’Ecole Centrale de Nantes, a permis de mettre en avant l’intérêt du procédé pour la fabrication de pièces aéronautiques. Un élément de structure aéronautique composé de raidisseurs a été fabriqué avec le procédé WAAM sur un substrat double courbure en alliage aluminium. Les difficultés accrues de réalisation ont pu être levées par l'emploi de la méthodologie développée dans le cadre de la thèseIn the field of additive manufacturing (AM), several processes are present and have different applications and levels of development: the main technologies are powder-bed based AM, powder projection and Wire Additive Manufacturing (WAM). We have studied, in this PhD work, the manufacturing of large scale components in aluminum alloy for aircraft industry with Wire Arc Additive Manufacturing (WAAM). This technology is based on a welding generator, a shielding gas protection and a feedstock (wire in this case). To solve this issue, several ways of research were investigated. The first one dealt with toolpath generation: several experiments have highlighted the importance of tool path generation and the tool orientation to manufacture complex parts and improve the part accuracy. The second one was about the validation of the material quality after deposit. Microstructural observations and mechanical tests have demonstrated the effect of process parameters on the deposit quality. Finally, in the context of a DGA/DGAC funded research project, whose partners were STELIA, CT INGENIERIE, CONSTELLIUM and l’Ecole Centrale de Nantes, the manufacturing of functional part in aluminum alloy has shown the interest of the process for aircraft industry. A structural component based on a double curvature geometry has been manufactured with WAAM. The methodologies developed in this PhD work have enabled us to solve the issues to manufacture that type of component
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Nwankpa, Uzoma Vincent. "Effectiveness of arc based processes and deposition strategies on additive manufacture structure for naval and aerospace applications". Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0010.
Testo completoAbstract (sommario):
Le processus de fabrication additive par fusion de fil métallique par arc électrique (Wire Arc Additive Manufacturing, WAAM) est devenu un procédé pertinent pour la fabrication de composants de structures complexes, qui étaient très compliqués à réaliser avec les méthodes de fabrication conventionnelles. Différents procédés à base d'arc électriques sont disponibles pour la mise en œuvre de matériaux tels que les alliages de titane ou d'aluminium et les aciers inoxydables, afin de produire des composants de grandes tailles. Néanmoins, il reste à déterminer quel est le meilleur procédé à base d'arc électrique à employer pour un matériau donné. Dans le cadre de cette thèse, plusieurs procédés à base d'arc électrique ont été étudiés pour déterminer s'ils convenaient à la fabrication de structures en acier inoxydable austénitique et en aluminium. Pour ce dernier, les travaux ont porté sur le procédé MIG/MAG de transfert de métal froid (CMT) en raison de son vaste choix de paramètres et de son faible apport de chaleur. Différentes stratégies de dépôt et l'utilisation des procédés TIG, MIG et Plasma ont été étudiés pour le dépôt d'aciers inoxydables austénitique par fabrication additive. Une étude approfondie des paramètres du processus tels que le courant, la vitesse de dévidage du fil et la vitesse de déplacement de la torche a été réalisée. Il a été montré que les propriétés mécaniques de chaque structure déposée par divers procédés à base d'arc satisfaisaient aux propriétés mécaniques requises. De plus, les stratégies de dépôt ont eu un impact plus important sur les propriétés mécaniques. En outre, la précision de la géométrie et le taux de ferrite diminuent en fonction de l'augmentation de l'apport de chaleur. Des études sur l'aluminium ont été menées avec le procédé CMT, une méthodologie de sélection de la meilleure synergie et du meilleur mode CMT pour le dépôt d'un fil prototype a été proposée. En outre, l'impact des stratégies de dépôt et de l'alternance de ces stratégies avec divers modes CMT sur l'atténuation de la propagation des fissures à partir de la base d'un composant WAAM ont été étudiées. Des études détaillées sur l'impact de la rampe des paramètres sur la précision de la géométrie de la paroi mince en aluminium ont été réalisées ainsi que sur la capacité de réaliser des structures suspendues. Enfin, l'étude a montré que le dépôt d'une structure en aluminium sur un support aux propriétés différentes est sujet à des fissures dues à une expansion et une contraction thermique inégales. Ainsi, ces travaux apportent des éléments d'aciers inoxydables austénitique et l'aluminium de paramétrage des procédés WAAM qui peux être significative dans l’objectif de réaliser des composants pour des applications navales et aéronautiquesWire and Arc Additive Manufacturing process is becoming an alternative technique used in manufacturing components of complex structures, which were unimaginable to achieve by conventional manufacturing methods. Various arc-based processes have been applied with titanium, aluminium, steel, and stainless steel to produce large components. Nevertheless, the best arc-based process for any given material of choice is yet to be addressed. In this research, several arc-based processes were investigated for their suitability to manufacture austenitic stainless steel and aluminium structures. However, the latter was confined to be deposited by cold metal transfer process (CMT) due to its high deposition rate and low heat input. Different deposition strategies and the use of gas metal arc, tungsten inert gas and plasma arc as heat sources for the deposition of austenitic stainless steel were investigated. An in-depth investigation of the process parameters such as current, wire feed speed and travel speed were carried out. It was found that the mechanical properties on each structure deposited by various arc-based processes satisfied the required mechanical properties Moreover, deposition strategies had moreimpact on the mechanical properties. Inaddition, the geometry accuracy and ferrite number decrease with respect to increased heat input. Aluminium studies were investigated with CMT process; a methodology to select the best CMT synergy and deposition mode for a prototype wire was proposed. Furthermore, the impact of deposition strategies and alternating these strategies with various CMT modes on mitigating crack propagation from the root of a WAAM component was investigated. Detailed studies on impact of ramping parameters on the aluminium thin wall geometry accuracy were performed. Afterwards the ramping parameters was implemented in the manufacture of suspended aluminium structures on steel support. Finally, the investigation showed that deposition of aluminium structure on a support of dissimilar properties is subject to crack due to uneven thermal expansion and contraction. The results of these research work on austenitic stainless steel and aluminium alloys for WAAM component can be of significance in the naval and aerospace applications
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Belhadj, Mohamed. "Fabrication additive par arc électrique : règles méthodes pour l’élaboration de pièces brutes en vue de leur parachèvement par usinage". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0003.
Testo completoAbstract (sommario):
La Fabrication Additive Arc-Fil (Wire Arc Additive Manufacturing) est une technologie de fabrication qui utilise du fil métallique comme matière première et un arc électrique comme source d’énergie. Le fil est déposé à une vitesse prédéfinie et fusionné grâce à l'arc électrique, soit sur un substrat, soit sur une couche préexistante. Cette recherche se concentre sur l'utilisation du procédé Cold Metal Transfer (CMT) appliqué à l'acier inoxydable austénitique 316L. Bien que cette technologie soit couramment employée avec succès pour la réparation, le défi actuel réside dans la production en série de pièces fonctionnelles, nécessitant ainsi la résolution de problèmes de conception et de fabrication spécifiques.Le premier objectif de cette thèse est d'évaluer l'impact des paramètres du procédé, en particulier la vitesse d'avance et le temps d'inter-passe, sur les dimensions, la qualité de surface des pièces et sur le parachèvement par usinage. Pour ce faire, un plan d'expériences a été mis en place, impliquant la fabrication de murs multicouches et multi cordons sur un substrat monté sur un support en aluminium. Ensuite, une face de chaque mur fabriqué a été usinée afin de déterminer la profondeur d'usinage nécessaire pour obtenir une surface exempte d'ondulations, et d'analyser la rugosité de surface ainsi que la dureté de ces zones. Enfin, une nouvelle méthode de recouvrement a été développée.Le deuxième objectif consiste à exploiter les résultats obtenus pour développer des méthodes et des règles permettant de passer de la conception 3D à la réalisation d'une pièce finale. Ces méthodes s’appuient sur une phase de fabrication additive et une phase de parachèvement par usinage. Ce processus vise à éliminer les dispersions géométriques et d’état de surface inhérentes au procédé WAAM, à déterminer la surépaisseur d’usinage nécessaire, et à intégrer les problématiques liées aux contraintes générées par le procédé primaire.Le dernier objectif est de comprendre les mécanismes de génération des contraintes résiduelles et des déformations induites par le procédé primaire. Pour ce faire, une modélisation thermomécanique du procédé a été développée. Elle a mis en évidence l'influence de la vitesse d'avance et du temps d'inter-passe sur le comportement thermomécaniqueWire Arc Additive Manufacturing is a manufacturing technology that uses metal wire as the raw material and an electric arc as the energy source. The wire is deposited at a predefined rate and fused by the arc, either onto a substrate or onto a pre-existing layer. This research focuses on the use of the Cold Metal Transfer (CMT) process applied to austenitic 316L stainless steel. While this technology is widely and successfully used for repair, the current challenge lies in the mass production of functional parts, requiring the resolution of specific design and manufacturing issues.The first objective of this thesis is to evaluate the impact of process parameters, in particular travel speed and interpass time, on part dimensions, surface quality and machining finish. To accomplish this, a design of experiments was set up, involving the manufacture of multi-layer, multi-bead walls on a substrate mounted on an aluminum support. Next, one face of each fabricated wall was machined to determine the machining depth required to achieve a waviness-free surface, and to analyze the surface roughness and hardness of these areas. Finally, a new overlapping method was developed.The second objective is to use the results obtained to develop methods and rules for moving from 3D design to the production of a final part. These methods rely on an additive manufacturing phase and a machining finishing phase. This process aims to eliminate geometric and surface finish variations inherent to the WAAM process, determine the necessary machining allowance, and incorporate issues related to the primary process.The final objective is to understand the mechanisms behind the generation of residual stresses and deformations induced by the primary process. To achieve this, a thermomechanical modeling of the process was developed, highlighting the influence of Travel speed and interpass time on the thermomechanical behavior
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Graf, Marcel, Sebastian Härtel e André Hälsig. "Numerische Auslegung des Mehrlagenschweißens als additives Fertigungsverfahren". Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-225946.
Testo completoAbstract (sommario):
Die additiven Fertigungstechnologien erleben seit einigen Jahren einen enormen Zuspruch bei der Herstellung von Einzelteilserien mit komplexen, endkonturnahen Geometrien und der Verarbeitung von Sonder- oder hybriden Werkstoffen. Prinzipiell lassen sich die Verfahren gemäß VDI- Richtlinie 3404 in drahtbasierte und pulverbasierte unterteilen. Eine weitere Unterteilung erfolgt hinsichtlich der Ausschmelztechnologie. Allen Verfahren ist gleich, dass schichtweise der Grundwerkstoff an den Stellen aufgetragen wird, wo er gemäß Endkontur benötigt wird. Damit ist ein immer wiederkehrender Wärmeeintrag verbunden, der somit Einfluss auf die Mikrostruktur der Bauteile und gleichzeitig auch auf die mechanischen Endeigenschaften ausübt. Die so erzeugten Komponenten sollten wenig Verzug oder Eigenspannungen als auch keine Porosität aufweisen, um die Gebrauchseigenschaften nicht negativ zu beeinflussen. Das Ziel ist es mittlerweile, diese verschiedenen Technologien numerisch abzubilden, um die Bauteileigenschaften vorherzusagen und ggf. Optimierungspotenziale zu eruieren.
Der untersuchte Prozess ist das drahtbasierte Mehrlagenschweißen mittels des Metallschutzgasschweißens, bei dem neben der Simulation auch die Validierung im Fokus hinsichtlich Geometrie und Gefügeausbildung in den Schweißlagen stand. Diesbezüglich wurden im vorliegenden Fall zum einen alle, für die numerische Simulation notwendigen Materialparameter (mechanische und thermophysikalische Kenngrößen) des Schweißzusatzwerkstoffes G4Si1 bestimmt und in ein kommerzielles FEM-Programm (MSC Marc Mentat) implementiert. Zum anderen erfolgt zukünftig die wissenschaftliche Analyse der Verbesserung der Bauteileigenschaft, in dem die Schweißnaht unter Ausnutzung der Schweißhitze warmumgeformt wird. Erste Ergebnisse numerischer Simulationsergebnisse zeigen positive Effekte. Diese zeigen mikrostrukturelle Veränderungen (Kornfeinung durch Rekristallisation) und führten letztendlich zur Steigerung der mechanischen Eigenschaften. Der Vorteil dieser Verfahrenskombination ist außerdem die Kompensation des Verzuges durch die gezielte Umformung und einem gleichzeitigen „Richten“.
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Kaya, Fuat Emre. "Applications of Additive Manufacturing in Construction and Historic Building Restoration/Rehabilitation". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22784/.
Testo completoAbstract (sommario):
The term “Additive Manufacturing” is described as the layered production of parts from a 3D file. Over the past century, this technology has evolved from a complement tool for conventional product development into an independent production method. Whereas high technology industries such as aerospace and medicine were already embraced additive manufacturing, structural engineering and architecture are lagging. Additive manufacturing has the potential to revolutionize the construction and restoration of historic buildings, with foreseeable benefits including highly complex and efficient structures with the reduction in material use and wastage, streamlining and expedition of the design-build process, improved customization. However, there are also challenges and demands: a new way of thinking for design and verifications for stability and serviceability of printed elements, the cost, the need for well-educated engineers.
In this dissertation, the current state of additive manufacturing in construction and historic building restoration/rehabilitation is reviewed as a combination of qualitative and quantitative-based studies. The research aims to give confidence to additive manufacturing applicability in these fields and stimulate further research. The opportunities and challenges are discussed by analysing concrete, polymer, and metal-based processes and their applications of additive manufacturing in the construction sector. A review of structural and non-structural applications in restoration projects, possible future applications in terms of structural strengthening are analysed and opportunities and challenges are identified and discussed. Based on the literature review and experimental lab tests, the outcome was obtained as the tensile mechanical properties are adequate for structural engineering applications. However, further interdisciplinary research on additive manufacturing is necessary to build confidence in structural engineers and architects.
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Kottman, Michael Andrew. "Additive Manufacturing of Maraging 250 Steels for the Rejuvenation and Repurposing of Die Casting Tooling". Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1416854466.
Testo completo
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Gomez, Ortega Arturo. "Prototypage rapide de pièces en alliage d’aluminium : étude du dépôt de matière et d’énergie lors de la fusion à l’arc d’un fil par le procédé MIG-CMT". Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS067/document.
Testo completoAbstract (sommario):
Un nouveau procédé de fabrication additive de pièces métalliques, basé sur le procédé de soudage à l’arc appelé CMT (Cold Metal Transfert), est étudié dans l’objectif de réaliser des pièces en alliage d’aluminium Al-5Si. Un banc de fabrication additive basé sur le principe des imprimantes 3D open source, sur lequel a été intégré le procédé CMT, a été spécialement développé. Le procédé CMT permet de contrôler la fusion d’un fil d’aluminium et son dépôt sous la forme de gouttelettes sur la surface de construction, formant après solidification des « cordons » qui peuvent être superposés pour fabriquer des pièces. L’influence des paramètres du procédé sur les phénomènes de transfert de matière et de chaleur lors de la fusion du métal et de son dépôt sur la surface de construction, ainsi que sur les caractéristiques géométriques des cordons déposés, dans le cas de dépôts mono-cordon, puis dans le cas de murs formés par la superposition d’un grand nombre de cordons, est étudiée. Plusieurs défauts géométriques ont été observés, et les conditions de leur apparition analysées, grâce notamment à l’utilisation d’une caméra rapide. La compréhension des relations entre paramètres procédé, mécanismes de transfert de chaleur et de matière, et géométrie des cordons, a permis de corriger ces défauts en identifiant puis modifiant les paramètres procédé responsables de leur apparition. Enfin, une méthode de contrôle en ligne du procédé, basée sur l’analyse des signaux de tension et d’intensité produits par le générateur de soudage au cours du phénomène de dépôt, qui permet de détecter précocement l’apparition de défauts, et ainsi de modifier les paramètres procédé avant qu’ils ne s’amplifient, a été proposéeA new additive manufacturing process for metallic parts, based on the arc welding process known as CMT (Cold Metal Transfer), is studied with the objective of building parts with the aluminium alloy Al5Si. A workbench for additive manufacturing based on the 3D printers open-source principle, on which the CMT generator was integrated, was specially developed. The CMT process allows to control the aluminium wire melting and its deposition under the form of droplets on the building surface, forming, after solidification, beads that can be superposed for the parts construction. The process parameters influence on the material transfer and heat transfer during the metal melting and deposition on the build surface, as well as on the geometric characteristics of the deposed beads, in the case of mono-layer deposits, and in the case of multi-layer walls, is studied. Many geometric defects were observed, and their apparition conditions analysed, thanks in particular to the use of a high-speed camera. The understanding of the relations between the process parameters, the melting and heat transfer mechanisms, and the beads geometry, allowed the defects correction by identifying and modifying the process parameters responsible of their apparition. Finally, an on-line control method for the process, based on the analysis of the voltage and current signals produced by the welding generator during the deposition phenomena, making possible the early detection of defects, and then the modification of the process parameters before they are amplified, has been proposed
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Diourté, Adama. "Génération et optimisation de trajectoire dans la fabrication additive par soudage à l'arc". Thesis, Toulouse 3, 2021. http://www.theses.fr/2021TOU30213.
Testo completoAbstract (sommario):
La fabrication d'additive par arcs électriques (WAAM) est en train de devenir la principale technologie de Fabrication Additive (FA) utilisée pour produire des pièces à parois minces de taille moyenne à grande (Ordre de grandeur : 1 m) à un coût moindre. Pour fabriquer une pièce avec cette technologie, la stratégie de planification du trajet utilisée est la 2.5D. Cette stratégie consiste à découper un modèle 3D en différentes couches planes et parallèles les unes aux autres. L'utilisation de cette stratégie limite la complexité des topologies réalisables en WAAM, notamment celles présentant de grandes variations de courbure, et implique plusieurs départs/arrêt de l'arc lors de son passage d'une couche à l'autre. Ceci induit des phénomènes transitoires dans lesquels le contrôle de l'approvisionnement en énergie et en matière est complexe. Dans cette thèse, une nouvelle stratégie de fabrication visant à réduire au minimum les phases de démarrage et d'arrêt de l'arc est présentée. L'objectif de cette stratégie, appelée "Génération de Trajectoire Continue Tridimensionnelle" (GTCT), est de générer une trajectoire continue en forme de spirale pour des pièces minces en boucle fermée. Une vitesse de fil constante couplée à une vitesse de déplacement adaptative permet une modulation de la géométrie de dépôt qui assure un approvisionnement continu en énergie et en matière tout au long du processus de fabrication. L'utilisation de la stratégie 5 axes couplées à la GTCT permet la fabrication de pièces fermées avec une procédure pour déterminer la zone de fermeture optimale, et des pièces sur des substrats non-plans utiles pour ajouter des fonctionnalités à une structure existante. La fabrication de ces pièces avec la GTCT et plusieurs évaluations numériques ont montré la fiabilité de cette stratégie et sa capacité à produire de nouvelles formes complexes avec une bonne restitution géométrique, difficile ou impossible à atteindre aujourd'hui en 2.5D avec la technologie WAAMWire Arc Additive Manufacturing (WAAM) is becoming the primary Additive Manufacturing (AM) technology used to produce medium to large (order of magnitude: 1 m) thin-walled parts at lower cost. To manufacture a part with this technology, the path planning strategy used is 2.5D. This strategy consists in cutting a 3D model into different plane layers parallel to each other. The use of this strategy limits the complexity of the topologies achievable in WAAM, especially those with large variations in curvature. It also implies several start/stop of the arc during its passage from one layer to another, which induces transient phenomena in which the control of energy and material supply is complex. In this thesis, a new manufacturing strategy to reduce the arc start/stop phases to a single cycle is presented. The objective of this strategy, called "Continuous Three-dimensional Path Planning" (CTPP), is to generate a continuous spiral-shaped trajectory for thin parts in a closed loop. An adaptive wire speed coupled with a constant travel speed allows a modulation of the deposition geometry that ensures a continuous supply of energy and material throughout the manufacturing process. The use of the 5-axis strategy coupled with CTPP allows the manufacturing of closed parts with a procedure to determine the optimal closure zone and parts on non-planar substrates useful for adding functionality to an existing structure. Two geometries based on continuous manufacturing with WAAM technology are presented to validate this approach. The manufacturing of these parts with CTPP and several numerical evaluations have shown the reliability of this strategy and its ability to produce new complex shapes with good geometrical restitution, difficult or impossible to achieve today in 2.5D with WAAM technology
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Antonysamy, Alphons Anandaraj. "Microstructure, texture and mechanical property evolution during additive manufacturing of Ti6Al4V alloy for aerospace applications". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/microstructure-texture-and-mechanical-property-evolution-during-additive-manufacturing-of-ti6al4v-alloy-for-aerospace-applications(03c4d403-822a-4bfd-a0f8-ef49eb65e7a0).html.
Testo completoAbstract (sommario):
Additive Manufacturing (AM) is an innovative manufacturing process which offers near-net shape fabrication of complex components, directly from CAD models, without dies or substantial machining, resulting in a reduction in lead-time, waste, and cost. For example, the buy-to-fly ratio for a titanium component machined from forged billet is typically 10-20:1 compared to 5-7:1 when manufactured by AM. However, the production rates for most AM processes are relatively slow and AM is consequently largely of interest to the aerospace, automotive and biomedical industries. In addition, the solidification conditions in AM with the Ti alloy commonly lead to undesirable coarse columnar primary β grain structures in components. The present research is focused on developing a fundamental understanding of the influence of the processing conditions on microstructure and texture evolution and their resulting effect on the mechanical properties during additive manufacturing with a Ti6Al4V alloy, using three different techniques, namely; 1) Selective laser melting (SLM) process, 2) Electron beam selective melting (EBSM) process and, 3) Wire arc additive manufacturing (WAAM) process. The most important finding in this work was that all the AM processes produced columnar β-grain structures which grow by epitaxial re-growth up through each melted layer. By thermal modelling using TS4D (Thermal Simulation in 4 Dimensions), it has been shown that the melt pool size increased and the cooling rate decreased from SLM to EBSM and to the WAAM process. The prior β grain size also increased with melt pool size from a finer size in the SLM to a moderate size in EBSM and to huge grains in WAAM that can be seen by eye. However, despite the large difference in power density between the processes, they all had similar G/R (thermal gradient/growth rate) ratios, which were predicted to lie in the columnar growth region in the solidification diagram. The EBSM process showed a pronounced local heterogeneity in the microstructure in local transition areas, when there was a change in geometry; for e.g. change in wall thickness, thin to thick capping section, cross-over’s, V-transitions, etc. By reconstruction of the high temperature β microstructure, it has been shown that all the AM platforms showed primary columnar β grains with a <001>β.
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Bourlet, Clément. "Développement de la fabrication additive par procédé arc-fil pour les aciers : caractérisation microstructurale et mécanique des dépôts en nuances ER100 et 316L pour la validation des propriétés d'emploi de pièces industrielles". Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0058.
Testo completoAbstract (sommario):
L'arc-fil est un nouveau procédé de fabrication additive utilisant une cellule desoudage robotisée pour la fabrication, couche par couche, de pièces de grandes dimensions. Ilpermet de réaliser des ébauches de pièces unitaires ou de petites séries avec des coûts et desdélais de fabrication réduits. Les premiers développements se sont principalement orientés sur laréalisation de pièces à forte valeur ajoutée en alliage de titane et d’aluminium pour le secteuraéronautique et aérospatial, et intéressent maintenant d’autres secteurs tels que les industriesnavales, pétrolières, ferroviaires et mécaniques utilisant des aciers. Ce travail propose uneméthodologie de sélection des paramètres et des stratégies de dépôts, avec le contrôle final despièces fabriquées. Il porte sur deux matériaux : un acier C-Mn à haute limite d’élasticité(ER100) et un acier inoxydable austénitique (316LSi). Le résultat des caractérisations permetd’établir le lien entre les conditions de fabrication, les dimensions géométriques et les propriétésmicrostructurales et mécaniques des pièces obtenues, ce qui conduit au final à une démarchepermettant de faire évoluer le procédé vers l’industrialisationWire-arc additive manufacturing is a new process using a common weldingrobotic cell to build large parts layer by layer. It allows building rough single pieces orsmall series parts with a low cost and a short delay. First developments were done ontitanium and aluminum parts for aeronautic and space applications, but more industriessuch as maritime, oil and gas, railway…are now interested into it. In this work, amethodology is proposed to define suitable process parameters and deposit’s strategies,with the final control of the elaborated parts. Developments are done on both highstrength steel ER100 and austenitic stainless steel 316LSi. The results of theexperimental characterisation enable to show the relations between the manufacturingconditions, the dimensions, the microstructure and the mechanicals properties of theparts, and finally lead to guidelines to evolve the wire-arc additive manufacturingtowards industrialisation
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Ó, Stefan Pereira do. "Wire and Arc Additive Manufacturing: Developments and Parts Characterization". Master's thesis, 2019. http://hdl.handle.net/10362/92301.
Testo completoAbstract (sommario):
Wire and arc additive manufacturing (WAAM) is a low capital investment technology that allows a reduction in material usage and production times while enabling the production of complex components. But despite its advantages, components produced in WAAM are prone to defects depending on the materials used and have overall inferior mechanical properties when compared to conventional processes.
This study focused on building and testing a system capable controlling the thermal cycles to manipulate the cooling rates and consequently the microstructure of produced parts in order to control the resulting hardness.
Two heat exchangers were built, one to heat and the other to cool the shielding gases. The exchangers were tested through the manufacturing of thin walls of 316L stainless steel and Inconel 625 superalloy using hot, ambient and cold argon gas. Obtained parts where characterized for their geometry, hardness and microstructure.
It was shown that varying the temperature of the shielding gas by itself is not enough to significantly influence the microstructure and mechanical properties of WAAM components. Using the cooling heat exchanger with cooling turned on caused an increase in hardness up to 30 HV and a decrease in primary dendrite arm spacing (PDAS) of 13.2 % for Inconel 625 while using the same heat exchanger without cooling caused an increase of 16.8 % in effective wall width (EWW) and a decrease of 15.8 % in height for 316L stainless steel. These differences were due to the cooling exchanger acting as a heat sink or as a heat accumulator depending on whether the cooling was turned on or off.
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Rodrigues, Tiago Miguel André. "Wire and arc additive manufacturing: equipment development and parts characterization". Master's thesis, 2018. http://hdl.handle.net/10362/63263.
Testo completoAbstract (sommario):
Wire and arc additive manufacturing (WAAM) is finding applications in different industrial sectors where it shows to be competitive compared to laser based additive manufacturing technologies. Two major advantages are associated to WAAM: it is a low capital investment technology with reduced running and maintenance costs and allows to manufacture parts with insipient or no porosities.
This study aimed at testing and validating a three-axis positioning system designed and manufactured at Mechanical Technology Group of Mechanical and Industrial Engineering Department at Nova University.
The major characteristics of the developed system are the following: 4.5 m3 working space, a maximum travel speed of 59 mm/s for the X and Y axes and of 2 mm/s for the Z axis. A maximum positional deviation of 0.02 mm, a minimal travel speed deviation of 0.24 mm/s and a displacement of 0.2 mm of the welding torch due to vibrations during a unidirectional movement.
The equipment was validated by manufacturing thin walls by deposition of a high strength low alloy (HSLA) steel wire with Gas Metal Arc Welding (GMAW), monitoring the thermal cycles by infrared thermography to evaluate them in different layers. Geometrical, microstructural and mechanical characterization of parts was performed.
Manufactured parts exhibited good surface finishing measured by the surface waviness that was around 300 μm and no internal defects were observed. Parts were isotropic as far as microstructural features and mechanical performance are concerned. The microstructure was mainly constituted by acicular ferrite and perlite with hardness below 320 HV. Energy dispersive spectrometry was performed, and no element loss was identified. Ultimate tensile strength varied between 700 and 809 MPa, depending on the process parameters. Resistance to impact was assessed by Charpy V impact tests with reduced size specimens and the absorbed energy registered was of 15 and 18 J, in longitudinal (Y) and normal (Z) directions, respectively. A ductile fracture surface was observed which is also a relevant indicator of mechanical performance of parts produced by WAAM in a HSLA steel.
27
Venturini, Giuseppe. "Architecture, design and implementation of CAM software for Wire and Arc Additive Manufacturing". Doctoral thesis, 2019. http://hdl.handle.net/2158/1153779.
Testo completoAbstract (sommario):
This PhD thesis deals with the automatic deposition toolpath generation for WAAM (Wire Arc Additive Manufacturing). WAAM is an Additive Manufacturing technology for metal components that uses an electric arc to melt a continuosly fed wire thus depositing a bead on a metal plate. It is a very primising technology since it is suitable to build parts large up to meters with an high deposition rate. However, automatic software to calculate the deposition toolpath for a part taking the CAD model as input is not easily available. Therefore, the PhD activity focused on the development of toolpath calculation algorithms for the generation of both three and five axes deposition toolpath. Moreover, the design and construction processes of a five axis machine to test the deposition toolpaths is presented together with a device able to reconstruct the geometry of the deposited material during the deposition phase that in the future could be used to obtain a numerical control with a closed loop approach able to automatically correct the deposition defects.
28
Rodideal, Nicolae. "Mechanical characterization and fatigue assessment of wire and arc additive manufactured HSLA steel parts". Master's thesis, 2020. http://hdl.handle.net/10362/114034.
Testo completoAbstract (sommario):
Additive manufacturing is one of the main foundations of Industry 4.0. It aims,
particularly, to increase productivity, reducing material waste due to machining and bring
many advantages that overcome the conventional manufacturing processes. Wire and Arc
Additive Manufacturing (WAAM) is an additive manufacturing process that employs an
electric arc as heat source in order to melt and add material. It shows great versatility and
freedom to fabricate parts using a layer-by-layer method of deposition. Despite the clear
advantages presented, there still needs more progress in order to make it industrially
feasible. One of the main challenges it faces is studying the mechanical properties bet on
the desired geometry, type of material and the adopted parameters before employing these
components in critical operational loading conditions.
This dissertation aimed to assess the mechanical properties and fatigue resistance of
HSLA parts manufactured by this technology. In this way, two type of samples were
produced – one of low heat-input and another of high heat-input, in which the changing
variable was the travel speed. For each type, three thin walled parts were obtained,
measuring 180 x 100 mm each.
After manufacturing all the required samples, three different regions were analysed –
bottom, middle and top. Next, all parts were assiduously prepared in order to proceed
with material characterization as well as testing, specifically, waviness, microstructure,
electrical conductivity, microhardness, uniaxial tensile tests and lastly fatigue tests, with
subsequent fracture surface observation through Scanning Electron Microscope (SEM).
Fatigue tests were performed at room temperature on low heat-input samples with
constant stress amplitude, stress ratio R=0.1 and frequencies between 12 Hz and 15 Hz.
The S-N curve of the experimental results is presented along with an explanation within
the context of the other characterization techniques results.
29
Lopes, João Carlos Galveias. "Feasibility of the milling process on HSLA parts produced with Wire and Arc Additive Manufacturing". Master's thesis, 2019. http://hdl.handle.net/10362/89773.
Testo completoAbstract (sommario):
Nowadays, additive manufacturing is considered an important propeller for a new industrial revolution. The recent advances in this manufacturing approach show that Wire and arc additive manufacturing (WAAM) has the potential to become a relevant method for the production of metallic components on a large scale. In this study, the need for the post-processing of these parts was recognized, which led to the characterization of the milling process regarding the several properties inherent to these parts.
The thin-walled structures required for the milling operations were manufactured using two different heat inputs. Then, a milling strategy that has in consideration the characteristics of such components was applied, where the process parameters and the tools utilized during the experiments were chosen based on the information provided by the tool manufacturer.
The results show that the properties inherent to the components manufactured via WAAM have influence in the milling process and that the quality of the surfaces improves with the increase of cutting speeds and with the decrease of feed per tooth. Nevertheless, more investigation is required to accurately study the milling process on WAAM parts due to the tool wear mechanisms associated with the workpiece material
30
Pires, José Carlos Barbosa. "Production of functionally graded Inconel 625/316L stainless steel parts by Wire and Arc Additive Manufacturing". Master's thesis, 2019. http://hdl.handle.net/10362/94538.
Testo completoAbstract (sommario):
O fabrico de materiais com gradiente de funcionalidade reveste-se de algumas dificulda-des pelo que as tecnologias de Fabrico Aditivo constituem uma alternativa interessante. A tecno-logia de deposição directa de energia usando arco eléctrico e fio (WAAM - Wire and Arc Additive Manufacturing) apresenta algumas vantagens, como sejam: baixos custos de equipamento inicial, de funcionamento e de manutenção, elevada taxa de deposição elevada e capacidade de produzir peças com geometria complexa sem defeitos internos.
Este trabalho teve como objectivo geral estudar a viabilidade do WAAM para a produção de peças com gradiente funcional depositando alternadamente aço inoxidável 316L e Inconel 625, dois materiais com excelente resistência à corrosão e boas propriedades mecânicas a alta tempe-ratura. Para isso adaptou-se o equipamento de WAAM existente no NTI/DEMI de modo a poder alimentar dois fios na direção do arco eléctrico. Foram feitas deposições com percentagens vari-áveis de cada um dos materiais e variando os parâmetros de processo e estudou-se o efeito destes na qualidade dos cordões depositados.
Com parâmetros otimizados, fizeram-se múltiplas deposições sucessivas em altura de modo a construir uma “parede” com gradiente de composição química. Analisou-se a microes-trutura face ao diagrama de equilíbrio de fases e a dureza das amostras.
Confirmou-se a viabilidade da utilização do sistema desenvolvido para a deposição de dois fios simultaneamente bem como para a criação de um gradiente de microestruturas ao longo do eixo vertical. Observou-se a existência de carbonetos dispersos confirmados pelos valores de dureza medidos. Na zona mais rica em Inconel, com cerca de 70 at. %, foi detetada uma fissura devida aos diferentes coeficientes de expansão linear do Inconel e do aço inoxidável.
Este foi o primeiro estudo deste tipo realizado no NTI, e requer como trabalho futuro a avaliação das propriedades mecânicas e da resistência à corrosão a alta temperatura, entre outras propriedades relevantes para aplicações industriais.
31
Bento, Emanuel Tavares. "ANÁLISE AO PROCESSO DE FABRICO POR WIRE-ARC ADDITIVE MANUFACTURING: Projeto e Realização de uma peça de comprovação de conceito". Master's thesis, 2021. http://hdl.handle.net/10316/98134.
Testo completoAbstract (sommario):
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaA 4ª Revolução Industrial, que decorre nos tempos atuais, pretende introduzir um conjunto de novas tecnologias no tecido industrial, entre elas, o fabrico aditivo. Este, por sua vez, promete revolucionar os processos produtivos atuais, uma vez que apresenta menores limitações em termos de complexidade geométrica, sendo possível adaptar a peça à respetiva função (em vez de a adaptar às limitações do método produtivo).Embora o foco inicial do fabrico aditivo tenha sido a implementação nos polímeros, em especial como método de ‘prototipagem rápida’, a classe de materiais com mais destaque na engenharia e indústria em geral é a dos metais, daí o recente interesse nas técnicas MAM, em especial as DED, que apresentam maiores taxas de deposição.No entanto, apesar das suas inúmeras vantagens, estas são técnicas ainda relativamente recentes, que carecem das décadas de conhecimento acumulado que os métodos convencionais possuem, pelo que, na sua maioria, ainda apresentam problemas a nível dimensional e das propriedades mecânicas obtidas, pelo que serão necessários mais estudos.Entre estas técnicas encontra-se o fabrico aditivo por arco elétrico (ou WAAM), a técnica em análise nesta dissertação. Assim, o objetivo deste trabalho é auxiliar no desenvolvimento desta tecnologia, nomeadamente, na análise inicial ao processo e no desenvolvimento duma metodologia que permita usar o sistema desenvolvido para obter peças a partir do respetivo modelo CAD.Esta dissertação é, portanto, composta por uma componente teórica onde é feita uma revisão sobre o fabrico aditivo em geral, a técnica WAAM, os sistemas cinemático e de controlo e a metodologia atualmente utilizada; e por uma componente prática onde é apresentado o sistema desenvolvido e, o procedimento experimental e respetivos resultados (ou seja, os problemas encontrados, soluções desenvolvidas e peças produzidas).
The 4th Industrial Revolution, which is taking place in current times, intends to introduce a set of new technologies into the manufacturing industry, one of them being 3D printing (or additive manufacturing). This, in turn, promises to revolutionize current production processes since it has fewer limitations in terms of geometric complexity, making it possible to adapt the part produced to its respective function (instead of adapting it to the limitations of the production method).Although its initial intent was to be implemented as a ‘rapid prototyping’ method to produce polymeric parts, the most prominent class of materials in engineering and industry in general are metals, hence the recent interest in MAM (metal additive manufacturing) techniques, in particular the ones classified under the DED (direct energy deposition) category, which have the highest deposition rates.However, despite their numerous advantages, these techniques are still relatively recent, lacking the decades of accumulated knowledge that conventional methods have. For that reason, they still present problems in terms of dimensional and mechanical properties, demonstrating the need for more studies to be performed.Among these techniques, wire-arc additive manufacturing (WAAM) is the method under analysis in this dissertation. Thus, the objective of this work is to assist in the development of this technology, namely, in the initial analysis of the process and in the development of a methodology that allows for the use of the system developed as a way to obtain parts from its CAD (computer-aided manufacturing) model.Therefore, this dissertation is composed of a theoretical part where a review is made about additive manufacturing in general, the WAAM technique, the kinematic and control systems and the methodology currently used, and by a practical part where the developed system and experimental procedure (problems found, solutions developed, and parts produced) are presented.
32
Gonçalves, Sérgio Manuel Mendes. "Projeto, realização e caracterização mecânica de uma peça estrutural produzida por sistema robotizado baseado na tecnologia Wire Arc Additive Mannufacturing (WAAM)". Master's thesis, 2021. http://hdl.handle.net/10316/97935.
Testo completoAbstract (sommario):
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaO consumo crescente de bens e a escassez de recursos representam um desafio para a sociedade. O Fabrico Aditivo surge como alternativa aos processos de fabrico tradicionais, rompendo com a atual forma de pensar e organização industrial, permitindo produzir na hora, em qualquer parte do mundo e com menos desperdícios.Para o Fabrico Aditivo de metais existem alguns processos disponíveis, utilizados sobretudo em setores de ponta com grande componente tecnológica. A maioria dessas técnicas, muito precisas, mas lentas, não se têm conseguido introduzir na construção metálica e mista, devido sobretudo ao elevado tempo de produção.O presente trabalho centra-se na execução por WAAM de uma peça estrutural em aço inoxidável. Partindo de uma peça em aço inox 316, aranha para união de vidros, utilizada nas fachadas envidraçadas de edifícios, criou-se uma réplica digital e programou-se um braço robótico para o seu fabrico através do processo de soldadura GMAW com controlo CMT. O processo decorreu por várias iterações, desde a afinação de parâmetros do equipamento em peças de geometria simples, evoluindo de complexidade até chegar forma da peça pretendida.O principal desafio e inovação deste estudo consistiu na aplicação prática do WAAM em peças estruturais de pequena dimensão, estabilização da deposição a nível de parâmetros e trajetória que produzam produtos isentos de defeitos. Após o fabrico as peças foram submetidas a ensaios, de forma a validar a produção e os parâmetros selecionados.Por fim é feita uma análise aos resultados, são expostas a principais lições apreendidas e são sugeridas algumas recomendações para aplicação em trabalhos futuros.
The increasing consumption of goods and the scarcity of resources represent a challenge for society. Additive Manufacturing emerges as an alternative to traditional manufacturing processes, breaking with the current way of thinking and industrial organization, allowing to produce on time, anywhere in the world and with less waste.For the Additive Manufacture of metals there are some processes available, mainly used in cutting-edge sectors with a large technological component. Most of these techniques, very precise but slow, are not in use into the metal and hybrid construction, mainly due to the high production time.The present work focuses on WAAM execution of a structural part made of stainless steel. Starting from a 316 stainless steel part, spider glass fitting used in the glazed facades of buildings, a digital twin was created, and a robotic arm was programmed for its manufacture through GMAW welding process with CMT control. The process took place through several iterations, from the tuning of equipment parameters in parts of simple geometry, evolving from complexity to reaching the shape of the desired part.The main challenge and innovation of this study was the practical application of WAAM in small structural parts, stabilization of the deposition mainly parameters and trajectory that produce defect-free products.After manufacture, the parts were tested to validate the production and the selected parameters.Finally, an analysis is made of the results, are exposed to main lessons learned and some recommendations are suggested for application in future work.
33
Mourão, João Nuno Paulino. "Inovação tecnológica do processo WAAM com vibração mecânica do banho de fusão". Master's thesis, 2021. http://hdl.handle.net/10362/120677.
Testo completoAbstract (sommario):
O processo Wire and Arc Additive Manufacturing (WAAM) é uma tecnologia de
Fabrico Aditivo (FA) que permite produzir peças com desperdício de material reduzido
e elevadas taxas de deposição. No entanto, é necessário um conhecimento mais
profundo do processo para melhorar a qualidade superficial, propriedades mecânicas e
diminuição da ocorrência de defeitos.
O principal objetivo desta dissertação foi estudar o efeito da vibração mecânica do
banho de fusão, com vista a promover um refinamento da microestrutura e melhorar as
propriedades mecânicas em peças produzidas com aço inoxidável ER316L e magnésio
AZ61A.
Foi desenvolvido um protótipo funcional que permitiu produzir amostras variando a
frequência, amplitude e movimento de vibração. Avaliaram-se os efeitos da vibração
mecânica na geometria e na microestrutura das amostras. Realizaram-se ensaios de
microdureza, condutividade elétrica e termografia. Foi medida a temperatura com
termopares e captados vídeos do processo em câmara lenta.
Conclui-se que o protótipo desenvolvido permitiu a realização de peças por WAAM
com vibração no banho de fusão. Nas amostras de ER316L a nucleação aumentou 47%
e o comprimento das dendrites diminuiu 44%. Nas amostras de AZ61A o tamanho de
grão diminuiu 59%. Tanto a frequência como a amplitude não afetaram
significativamente a altura e largura das paredes, no entanto, as ondulações periódicas
tornaram-se 20% menores a 10 Hz de frequência e 2 mm de amplitude. A vibração não
foi suficiente para provocar uma diminuição significativa da condutividade elétrica ou da
dureza nas amostras.Wire and Arc Additive Manufacturing (WAAM) is an Additive Manufacturing (AM) technology that produces parts with reduced material waste and high deposition rate. However, a deeper knowledge of the process is needed to improve surface quality, mechanical properties and decrease defects. The main objective of this dissertation was to study the effect of the mechanical vibration of the melting pool, in order to promote grain refinement and improve the mechanical properties in parts produced with stainless steel ER316L and magnesium AZ61A. A functional prototype was developed that produced the variation in frequency, amplitude and type of vibration. The effects of mechanical vibration on geometry and microstructure are evaluated. Microhardness, electrical conductivity and thermography tests were carried out. The temperature was measured with thermocouples and videos of the process were captured in slow motion. It is concluded that the developed prototype allowed the realization of parts by WAAM with vibration in the melting pool. In ER316L samples, nucleation increased 47% and dendrite length decreased 44%. In the samples of AZ61A the grain size decreased by 59%. Both the frequency and the amplitude did not affect complementing the height and width of the walls, however, as periodic ripples become 20% finer at 10 Hz frequency and 2 mm amplitude. The vibration was not sufficient to cause a decrease in electrical conductivity or hardness in the configurations.