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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Processing of toughened cyanate ester matrix composites

Rau, Anand V. 06 June 2008 (has links)
This investigation explored the feasibility of recently developed toughened cyanate ester networks as candidate materials for high performance composite matrix applications. The resin investigated was a Bisphenol-A cyanate ester toughened with hydroxy functionalized phenolphthalein based amorphous poly(arylene ether sulfone). The thermoplastic modified toughened networks exhibited improvement in the fracture toughness over the base cyanate ester networks without significant reductions in mechanical properties or glass transition temperature. Void free, unidirectional carbon fiber prepreg was successfully manufactured with the toughened cyanate resin using a solventless hot-melt technique. The resin mass fraction of the prepregs was between 31 and 35%. The carbon fiber, toughened cyanate ester prepreg was fabricated into composite panels for mechanical and physical testing. The cure cycle used to manufacture the composite laminates was developed with the aid of a process simulation model developed by Loos and Springer. In order to accurately simulate the resin curing and flow processes, the cure reaction kinetics and melt viscosity was characterized as a function of temperature and degree of cure and input into the simulation model. The model generated cure cycle was used in the manufacture 8-ply unidirectional and 16-ply quasi-isotropic composite laminates. The manufactured laminates were well consolidated to the specified fiber volume fraction between 59 and 60%. Photomicrographs showed that the laminates are void free, the fiber and resin distribution is uniform and fiber wet-out is very good. Mechanical tests were performed to measure the impact damage resistance and shear properties of the toughened cyanate ester resin composites. The results show improvements in impact damage resistance compared with the commonly used hot-melt epoxy resin composites. The influence of processing on performance was observed from the results of shear tests. Carbon fabric composite panels were manufactured by liquid molding processes (resin transfer molding and resin film infusion), with a series of four toughened cyanate ester resins generated by varying the concentration and the molecular weight of the toughener. The panels were subjected to physical, damage tolerance, and fracture toughness tests. The results of physical testing indicate consistently uniform quality, and the void content was found to be less than 2%. The toughened cyanate ester composites exhibited significantly improved impact damage resistance and tolerance compared with hot-melt epoxy systems. Marked increase in the mode II fracture toughness were observed with an increase in the concentration and the molecular weight of the toughener. / Ph. D.
482

Verification of a two-dimensional infiltration model for the resin transfer molding process

Hammond, Vincent H. 12 March 2009 (has links)
A two-dimensional finite element model for the infiltration of a dry textile preform by an injected resin has been verified. The model, which is based on the finite element/control volume technique, determines the total infiltration time and the pressure increase at the mold inlet associated with the RTM process. Important input data for the model are the compaction and permeability behavior of the preform along with the kinetic and rheological behavior of the resin. The compaction behavior for several textile preforms was determined by experimental methods. A power law regression model was used to relate fiber volume fraction to the applied compaction pressure. Results showed a large increase in fiber volume fraction with the initial application of pressure. However, as the maximum fiber volume fraction was approached, the amount of compaction pressure required to decrease the porosity of the preform rapidly increased. Similarly, a power law regression model was used to relate permeability to the fiber volume fraction of the preform. Two methods were used to measure the permeability of the textile preform. The first, known as the steady state method, measures the permeability of a saturated preform under constant flow rate conditions. The second, denoted the advancing front method, determines the permeability of a dry preform to an infiltrating fluid. Water, corn oil, and an epoxy resin, Epon 815, were used to determine the effect of fluid type and viscosity on the steady state permeability behavior of the preform. Permeability values measured with the different fluids showed that fluid viscosity had no influence on the permeability behavior of 162 E-glass and TTI IM7/8HS preforms. Permeabilities measured from steady state and advancing front experiments for the warp direction of 162 E-glass fabric were similar. This behavior was noticed for tests conducted with corn oil and Epon 815. Comparable behavior was observed for the warp direction of the TTl 1M7/8HS preform and corn oil. Fluid/fiber interaction was measured through the use of the single fiber pull-out test. The surface tension of both the corn oil and Epon 815 was determined. The contact angle between these two fluids and glass and carbon fibers was also measured. These tests indicated that the glass fiber had a lower contact angle than the carbon fiber and therefore is wet out better than the carbon fiber by both fluids. This result is attributed to the sizing commonly used on the carbon fibers. Mold filling and flow visualization experiments were performed to verify the analytical computer model. Frequency dependent electromagnetic sensors were used to monitor the resin flow front as a function of time. For the flow visualization tests, a video camera and high resolution tape recorder were used to record the experimental flow fronts. Comparisons between experimental and model predicted flow fronts agreed well for all tests. For the mold filling tests conducted at constant flow rate injection, the model was able to accurately predict the pressure increase at the mold inlet during the infiltration process. A kinetics model developed to predict the degree of cure as a function of time for the injected resin accurately calculated the increase in the degree of cure during the subsequent cure cycle. / Master of Science
483

Technologies de fabrication avancée versus le moulage d'implants cornéens : impression 3D vs moulage d’une Kératoprothèse

Barrakad, Ines 08 1900 (has links)
La cornée permet à la lumière de pénétrer dans l’œil : c’est notre fenêtre sur le monde. Les déficiences visuelles dues à des défauts de la cornée proviennent de diverses causes, génétiques ou environnementales. La greffe de cornée permet aux patients qui en souffre de recouvrer la vue. Les Kératoprothèses (KPros) sont des prothèses cornéennes pour les patients qui ne peuvent pas bénéficier d’une greffe de cornée en raison du risque de rejet. Les principales limitations de ces Kératoprothèses résident dans l’absence d’intégration à long terme et leur dépendance au matériel donneur humain. Ici, nous avons fabriqué une Kératoprothèse synthétique et transparente biocompatible et suturable en utilisant des méthodes de fabrication avancée (impression 3D) et moulage. La partie optique (noyau) agit comme une fenêtre, mais aussi comme un squelette pour la jupe d’hydrogel. La formulation développée pour l’hydrogel permet de promouvoir la biointégration de l’implant grâce à sa colonisation par les cellules de l'hôte. Ce modèle permet donc de suturer la Kératoprothèse et promouvoir sa biointégration complète. Cette étude de faisabilité établit une méthodologie de production d’un nouveau modèle de Kératoprothèse avec une partie centrale transparente – produite par impression 3D ou moulage – et une jupe d’hydrogel. Contrairement aux modèles disponibles sur le marché, il s’agit ici d’un modèle de KPro qui n’est pas rigide et ne nécessite pas de matériel biologique. Dans un premier temps, l’optique centrale et le squelette ont été conçus à l’aide de Fusion 360. La production de la partie optique a ensuite été réalisée par moulage de PDMS ou impression 3D de résine biocompatible. Chaque méthode de production présente différents avantages et limitations telles que les matériaux pouvant être utilisés ou les propriétés mécaniques et optiques de ces dernières, notamment postproduction. En les combinant, ce modèle de KPro et ces méthodes de productions peuvent nous aider à éviter les complications associées à l’implantation de Kératoprothèses actuellement présentes sur le marché. / The cornea allows light to enter the eye: it is our window to the world. Visual deficiencies due to corneal defects originate from various causes, both genetic and environmental. Corneal transplants enable patients suffering from visual deficiencies to regain their sight. Keratoprostheses are corneal prostheses for patients who cannot benefit from a corneal transplant due to the risk of rejection. The main limitations of these Keratoprostheses lie in their lack of long-term integration and their dependence on human donor material. Here, we have fabricated a biocompatible and suturable synthetic and transparent Keratoprosthesis using advanced manufacturing (3D printing) and casting methods. The optical part (core) acts as a window, but also as a skeleton for the hydrogel skirt. The formulation developed for the hydrogel promotes biointegration of the implant through its colonization by host cells. This model can therefore be used to suture the keratoprosthesis and promote complete biointegration. This feasibility study establishes a methodology for producing a new Keratoprosthesis model with a transparent central part - produced by 3D printing or molding - and a hydrogel skirt. Unlike the models available on the market, this KPro model is not rigid and does not require biological material. Initially, the central optics and skeleton were designed using Fusion 360. The optical part was then produced by molding PDMS or 3D printing biocompatible resin. Each production method offers different advantages and limitations, such as the materials that can be used, or the mechanical and optical properties of the latter, particularly post-production. By combining them, this KPro model and these production methods can help us avoid the complications associated with the implantation of Keratoprostheses currently on the market.
484

Technologie vstřikování zkušebních těles z termoplastů / Technology of injection molding of thermoplastic test specimens

Khamzin, Yersin January 2021 (has links)
The diploma thesis focuses on the optimization of technological parameters of plastic injection molding and the study of the influence of technological parameters on the quality of molded test specimens’ type 1A. The quality of molded parts for 3 types of polypropylene (PP) with different melt flow rate (Mosten GB 002, Mosten GB 218, Mosten MA 230) and 1 type of polystyrene (PS) (Krasten PS GP 154) was evaluated in terms of dimensional stability and weight. The contribution of software for modeling the plastic injection molding process was evaluated in this work. SOLIDWORKS Plastics software was used to optimize technological parameters. The construction of the bodies, mold and cooling system was constructed, and test bodies were produced on the basis of parameters obtained from the simulation of the injection molding process. Their quality parameters were compared with a 3D model and for each of the studied materials the optimal technological parameters were selected in terms of quality and the degree of influence of individual injection parameters on the quality of moldings was evaluated. The accordance of the results of the theoretical simulation with the real experiment was proved and a computational module independent of the optimized quality parameters, generally suitable for optimizing the quality parameters of the injected parts, was developed.
485

Spritzgießtechnische Herstellung duroplastgebundener Dauermagnete

Maenz, Torsten 25 October 2018 (has links)
Kunststoffgebundene Dauermagnete kommen bereits seit einem dreiviertel Jahrhundert in diversen Anwendungen zum Einsatz. Dabei werden die gängigen Kunststoffverarbeitungsverfahren wie beispielsweise Spritzgießen, Extrudieren, Pressen und Kalandrieren angewandt. Ähnlich zu der Aufteilung in der Verarbeitung von herkömmlichen Kunststoffen, werden auch für die kunststoffgebundenen Dauermagnete nur selten duroplastische Matrixmaterialien im Spritzgießverfahren eingesetzt. Dabei bringt gerade diese Werkstoffklasse hervorragende Eigenschaften mit sich, die eine Verbesserung der Eigenschaften von kunststoffgebundenen Dauermagneten zur Folge haben können. Neben der Medien- und Temperaturbeständigkeit dieser Werkstoffklasse spielt dabei auch deren Viskosität eine bedeutende Rolle für diese Anwendung. Im Rahmen der vorliegenden Arbeit soll geprüft werden, ob der Einsatz duroplastischer Matrixmaterialien zu einer Verbesserung der Eigenschaften kunststoffgebundener Dauermagnete führen kann. Hierfür werden anisotrope Magnetpartikel in den Kunststoff eincompoundiert und während der Verarbeitung im Spritzgießverfahren orientiert. Dies geschieht durch ein integriertes Magnetfeld im Spritzgießwerkzeug. Insbesondere sollen der Einfluss des Matrixmaterials, der Partikelgeometrie, der Fließrichtung sowie des Richtfeldes auf die Partikelorientierung untersucht werden. Zusammen mit grundlegenden analytischen Untersuchungen der Ausgangsmaterialien sollen abschließend Richtlinien für eine Bauteilauslegung definiert und erste Ansätze für eine Simulation der magnetischen Bauteileigenschaften erarbeitet werden. / Polymer bonded magnets are used for different applications for over 70 years yet. These materials are produced within known polymer processing procedures as injection molding, extruding, compression molding and calendaring. However, as for standard plastics thermoset materials are seldom used in injection molding even though they show great potential regarding temperature and media resistance as well as in terms of a low viscosity. These properties could be of use in case of polymer bonded magnets. Within this work the use of thermoset matrix materials for polymer bonded magnets should be evaluated and thus their properties shall be improved. Therefore anistotropic magnetic particles will be incorporated in the thermoset matrix and they will be oriented during the injection molding process which requires a magnetic field in the cavity during processing. Especially the influences of the matrix material, the particle geometry, the flow direction and the aligning field on the particle orientation should be investigated and together with fundamental analytical procedures guidelines for engineering of parts should be generated as well as first approaches for a simulation of the part properties shall be given.
486

ADDITIVE MANUFACTURING OF COMPONENTS FOR IN-DIE CAVITY USE, SUITABLE TO WITHSTAND ALUMINIUM HIGH PRESSURE DIE CASTING (HPDC) PROCESS CONDITIONS

Pereira, Manuel. Filipe. Viana. Teotonio. January 2013 (has links)
Thesis (M. Tech. (Engineering: Mechanical)) -- Central University of Technology, Free State, 2013 / This research examines the suitability of Additive Manufacturing (AM) for manufacturing dies used in aluminium high pressure die casting. The study was guided by the following objectives: • The reviews of applicable literature sources that outline technical and application aspects of AM in plastic injection moulds and the possibilities of applying it to high pressure casting die. • To introduce AM grown die components in die manufacture. Further, to develop a methodology that will allow industry to apply AM technology to die manufacture. • Revolutionise the way die manufacture is done. The potential for AM technologies is to deliver faster die manufacture turnaround time by requiring a drastically reduced amount of high level machining accuracy. It also reduces the number of complex mechanical material removal operations. Fewer critical steps required by suitable AM technology platforms able to grow fully dense metal components on die casting tools able to produce production runs. • Furthermore, promising competitive advantages are anticipated on savings to be attained on the casting processing side. AM technology allows incorporation of features in a die cavity not possible to machine with current machining approaches and technology. One such example is conformal cooling or heating of die cavities. This approach was successfully used in plastic injection mould cavities resulting in savings on both the part quality as well as the reduction on cycle time required to produce it (LaserCUSING®, 2007). AM technology has evolved to a point where as a medium for fast creation of an object, it has surpassed traditional manufacturing processes allowing for rapidly bridging the gap between ideas to part in hand. The suitability of the AM approach in accelerating the die manufacturing process sometime in the near future cannot be dismissed or ignored. The research showed that there is promise for application of the technology in the not too distant future. In the South African context, the current number and affordability of suitable AM platforms is one of the main stumbling blocks in effecting more widespread applied research aimed at introduction of the technology to die manufacture.
487

Thermal management of moulds and dies : a contribution to improved design and manufacture of tooling for injection moulding

Moammer, A. A. 03 1900 (has links)
Thesis (PhD (Industrial Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Injection moulding of polymer components is subject to ever increasing demands for improved part quality and production rate. It is widely recognised that the mould cooling strategy employed is crucial to achieving these goals. A brief overview of injection moulding units and different types of injection moulds is given. The modern Additive Manufacturing (AM) technology for processing metal powders such as Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) offers almost full freedom to the mould designer. Some of these modern manufacturing methods based on metal powders, which are able to produce complex cooling channels are analysed. A drastic change has entered the mould design domain - shifting the paradigm from design for manufacture to manufacture for design. In combination with suitable AM methods the concept of surface cooling moulds can now be efficiently implemented. This study presents a new approach of predicting the minimum cooling time required for the produced part. Different cooling layouts are analysed taking the heat transfer into consideration. The lumped heat capacity method is implemented in this research in order to determine the minimum cooling cycle time required. A new approach was developed to determine the most suitable cooling layout configuration, such as conventional cooling, conformal cooling or surface cooling, required for a moulded part based on its characteristics such as shape complexity, space available for the cooling layout, part quality requirements, production volume, and product life cycle. A mould cooling design process including simulation, reverse engineering and manufacturing of the mould insert was implemented in this study. In order to validate the generic model developed during the course of this research comparative experiments were carried out to determine the difference in performance of injection moulding using conventional or surface cooling methods. The experimental results showed a significant improvement in part quality produced with reduced cycle times using the surface cooling method. / AFRIKAANSE OPSOMMING: ‘Injection Moulding’ van polimeer komponente word al meer gedruk vir verbeterde kwaliteit en vinniger produksie tyd. Dit is orals bekend dat die gietvorm afkoeling strategie ‘n groot rol speel om hierdie twee doelwitte te bereik. Eers word ‘n kort oorslag gegee van ‘Injection Moulding’ eenhede en van verskillende ‘Injection Moulding’ vorms. Die moderne Aditatiewe Vervaardigingstegnologie vir die prosessering van metaal poeiers soos bv. Direkte Metaal Laser Sintering (DMLS) en Selektiewe Laser Smelting (SLM) bied basies volle vryheid ten opsigte van gietvorm ontwerp. Party van die moderne vervaadigings metodes, wat op metaal poeiers gebaseer is, wat komplekse koelings kanale kan produseer word geanaliseer. Die ontwerpers arena het ‘n groot verandering ondergaan deurdat die fokus van ontwerp vir vervaardiging verskuif het na vervaardiging vir ontwerp. In kombinasie met toepaslike aditatiewe vervaardigings metodes kan oppervlak verkoeling nou effektief geïmplementeer word. Hierdie studie bied a nuwe manier om die minimum verkoelings tyd benodig vir ‘n part te voorspel. Verskeie verkoelings uitlegte word geanaliseer waar hitte oordrag in ag geneem word. Die “lumped heat capacity” metode word gebruik om die minimum siklus tyd te bepaal. ‘n Nuwe benadering is ontwikkel om die mees geskikste verkoelings uitleg soos bv. konvensionele verkoeling, konvorme verkoeling of oppervlak verkoeling te bepaal vir ‘n spesifieke part gebaseer op die part se vorm kompleksiteit, spasie beskikbaar vir verkoelings kanale, kwaliteit vereistes en produk lewensiklus. Die volgende is in die studie geïmplementeer: ‘n vorm verkoelings ontwerp proses met simulasie, ‘reverse engineering’ en vervaardiging van die vorm insetsel. Om die generiese model te verifieer gedurende die studie is vergelykende eksperimente uitgevoer om die verskil in prestasie te bepaal tussen die gebruik van konvensionele en oppervlak verkoelings metodes. Die eksperimentele resultate het ‘n beduidende verbetering in part kwaliteit getoon met ‘n verkorte siklus tyd tydens die gebruik van die oppervlag verkoelings metode.
488

Étude numérique et expérimentale de procédé d'élaboration des matériaux composites par infusion de résine

Wang, Peng 23 March 2010 (has links) (PDF)
En aéronautique, l'élaboration via des pré-imprégnés n'est pas toujours adaptées àla fabrication de nouvelles pièces de formes complexes ou de grandes dimensions. Desprocédés directs existent, dénommés Liquid Composites Molding (LCM), tels que leResin Transfer Moulding (RTM) ou les procédés d'infusion de résine, comme le LiquidResin Infusion (LRI) et le Resin Film Infusion (RFI). Actuellement, environ 5 à 10%des pièces composites sont fabriqués par ces procédés directs. Avec le procédé RTM,les tolérances dimensionnelles et la porosité peuvent être maîtrisées et on peut atteindredes pièces haute qualité, mais son industrialisation est complexe et les modèlesmécaniques doivent être améliorés pour réaliser des simulations représentatives. Parcontre, les procédés d'infusion peuvent être utilisés dans des conditions plus flexibles,par exemple, dans des moules ouverts à sac vide en nylon ou silicone, à faible coût. Parconséquent, les procédés de LRI et RFI sont particulièrement adaptés pour les petites etmoyennes entreprises car les investissements sont plus faibles par rapport à d'autresprocédés de fabrication.Les procédés par infusion de résine LRI ou RFI sont basés sur l'écoulement d'unerésine liquide (pour RFI, après le cycle de température, la résine solide obtenir son étatliquide) à travers l'épaisseur d'un renfort fibreux sec dénommé préforme.L'optimisation du procédé est difficile à réaliser car le volume de la préforme changefortement pendant le procédé car elle est soumise à une pression extérieure et qu'il n'ya pas de contre-moule. Pour optimiser les paramètres de fabrication des matériauxcomposites par infusion de résine, il est nécessaire de mettre en oeuvre un modèlenumérique. Récemment, une modélisation de l'écoulement d'un fluide isotherme dansun milieu poreux compressible a été développée par P. Celle [1]. Avec ce modèlenumérique, nous avons simulé des cas test en 2D pour des géométries industriellesclassiques. Pour valider ce modèle numérique, des essais d'infusion d'une plaque par leprocédé LRI dans des conditions industrielles ont été réalisés. D'une part, la simulationnumérique permet de calculer le temps de remplissage, l'épaisseur de la préforme et lamasse de la résine durant l'infusion. D'autre part, nous avons suivi de procédéexpérimentalement par des micro-thermocouples, la fibre optique et la projection defranges. Un des points clefs de l'approche expérimentale est que l'écoulement de larésine et le comportement de la préforme dépendent intrinsèquement de paramètres quiévoluent pendant l'infusion de la résine, tels que la variation de l'épaisseur, le temps deremplissage et le taux volumique de fibres, via la perméabilité. Enfin, une comparaisonentre les résultats expérimentaux et la simulation numérique permet de valider lemodèle numérique. Cette confrontation des résultats permettra de mettre en lumière lesdifficultés et les limites de ce modèle numérique, afin d'améliorer les futurs modèles.De plus, ces deux approches constituent un bon moyen d'étudier et d'approfondir nosconnaissances sur les procédés d'infusion de résine, tout en développant un outil desimulation indispensable à la conception de pièces composites avancées.
489

Technical Analysis of Flax Fiber Reinforced Polypropylene : Prerequisites for Processing and Recycling / Teknisk analys av linfiber förstärkt polypropen : Förutsättningar för bearbetning och återvinning

Mattsson, Josephie January 2014 (has links)
Nowadays, when environmental concerns are becoming increasingly important are there great interest in natural materials and recyclability. The possibility of reusing materials with maintained mechanical properties are essential for sustainability. Today produced approximately 90,000 tons of natural fiber reinforced composites in Europe of those are 40,000 tons compression molded of which the automotive industry uses 95%. Natural fiber reinforced composites is recyclable and therefore interesting in many applications. Also, natural fiber reinforced composites is inexpensive, light in weight and shows decent mechanical properties which makes them attractive to manufactures. However, the problem with natural fiber reinforced composites is the poor adhesion between fiber and matrix, the sensitivity of humidity and their low thermal stability. Those problems could be overcome by addition of compatibilizer and reactive filler. This study will examine the technical requirement in order to develop a sustainable and recyclable biocomposite. It investigates the composition of matrix (polypropylene), fiber (flax), compatibilizer (maleic anhydride grafted polypropylene) and reactive filler (CaO) in order to obtain various combinations of stiffness, strength and processability. The two main methods used for preparing samples were compounding and injection molding. Results shows that 20 wt% flax was the optimal fiber content and that maleic anhydride grafted polypropylene is a very good compatibilizer by enhancing the strength significant. Surprisingly was the strength impaired due to the addition of CaO. The composition of 20 wt% flax, 1 wt% maleic anhydride grafted polypropylene and 79 wt% polypropylene is the technically most favorable composition.
490

Development and characterization of polymer- metallic powder feedstocks for micro-injection molding / Développement et caractérisation de mélanges polymères-poudres métalliques pour le micro moulage par injection

Kong, Xiangji 07 February 2011 (has links)
Le micro-moulage par Injection de Poudres (Micro-PIM) est l’une des technologies permettant de réaliser des micro-composants de très petites dimensions, associés à la miniaturisation et la fonctionnalisation dans différents domaines d’applications. La thèse concerne l’élaboration et la caractérisation de mélanges basés sur des poudres d’acier inoxydable de type 316L, l’identification des paramètres physiques associés à l’étape de densification est traitée. Des modélisations physiques et des simulations numériques de l’étape de densification par diffusion à l’état solide, sont ensuite proposées.De nouvelles formulations de mélanges à base de liants polymériques ont été développées pour différentes granulométries de poudres d’acier inoxydable de type 316L (5 µm et 16 µm). Les différents mélanges élaborés ont été élaborés et validés grâce à des comparatifs entre couples de mélangeages et courbes de viscosité de cisaillement. Les mélanges élaborés avec une formulation de base composée de polypropylène, de cire paraffine et d’acide stéarique, sont adaptés pour les deux types de poudre, et conduisent à des résultats significatifs pour les différents tests réalisés, conduisant à un couple de mélangeage et à une viscosité de cisaillement relativement faibles par rapport aux autres formulations. Le taux de charge critique obtenu pour l’acier inoxydable 316L (5 µm), avec la formulation optimale, est de 68% et a été déterminé par différentes méthodes. Les essais de micro-injection pour le mono-matériau (316L mélange) et les bi-matériaux (mélange de 316 L et Cu) ont été analysés en détail. Des tests d’homogénéité ont été réalisés avant et après l’étape d’injection.Un modèle thermo-élasto-viscoplastique approprié pour modéliser l’étape de densification a été utilisé pour la simulation de la densification des micro-composants. Les paramètres d’identification du modèle physique ont été identifiés pour des mélanges de poudres d’acier 316L (5 µm), pour différents taux de charge (62%, 64% et 66%). Des essais de flexion 3 points et de compression ont été réalisé à l’intérieur d’un dilatomètre vertical avec trois cinétiques de densification (5 °C/min, 10 °C/min et 15 °C/min). Les résultats obtenus par dilatométrie, ont permis l’identification du module de viscosité de cisaillement G, du module de compressibilité K, et de la contrainte de densification σs, Le modèle de comportement associé à la densification, incluant les paramètres identifiés a été implémenté dans le code éléments finis Abaqus©. Des éléments finis adaptés ont été utilisés, tant pour le support, que les quatre micro-éprouvettes de référence. Les simulations de l’étape de densification pour trois différentes cinétiques (5 °C/min, 10 °C/min et 15 °C/min) à 1200°C, ont été réalisées pour l’ensemble des micro-composants dont les taux de charge correspondent respectivement à 62%, 64% et 66%. Les retraits et densités relatives des micro-composants obtenus par simulation sont en très bonne corrélation avec les résultats expérimentaux / Micro-Powder Injection Moulding (Micro-PIM) technology is one of the key technologies that permit to fit with the increasing demands for smaller parts associated to miniaturization and functionalization in different application fields. The thesis focuses first on the elaboration and characterization of polymer-powder mixtures based on 316L stainless steel powders, and then on the identification of physical and material parameters related to the sintering stage and to the numerical simulations of the sintering process. Mixtures formulation with new binder systems based on different polymeric components have been developed for 316L stainless steel powders (5 µm and 16 µm). The characterization of the resulting mixtures for each group is carried out using mixing torque tests and viscosity tests. The mixture associated to the formulation comprising polypropylene + paraffin wax + stearic acid is well adapted for both powders and has been retained in the subsequent tests, due to the low value of the mixing torque and shear viscosity. The critical powder volume loading with 316L stainless steel powder (5 µm) according to the retained formulation has been established to 68% using four different methods. Micro mono-material injection (with 316L stainless steel mélange) and bi-material injection (with 316L stainless steel mélange and Cu mélange) are properly investigated. Homogeneity tests are observed for mixtures before and after injection. A physical model well suited for sintering stage is proposed for the simulation of sintering stage. The identification of physical parameters associated to proposed model are defined from the sintering stages in considering 316L stainless steel (5 µm)mixtures with various powder volume loadings (62%, 64% and 66%). Beam-bending tests and free sintering tests and thermo-Mechanical-Analyses (TMA) have also investigated. Three sintering stages corresponding to heating rates at 5 °C/min, 10 °C/min and 15 °C/min are used during both beam-bending tests and free sintering tests. On basis of the results obtained from dilatometry measurements, the shear viscosity module G, the bulk viscosity module K and the sintering stress σs are identified using Matlab® software. Afterwards, the sintering model is implemented in the Abaqus® finite element code, and appropriate finite elements have been used for the support and micro-specimens, respectively. The physical material parameters resulting from the identification experiments are used to establish the proper 316L stainless steel mixture, in combination with G, K and σs parameters. Finally, the sintering stages up to 1200 °C with three heating rates (5 °C/min, 10 °C/min and 15 °C/min) are also simulated corresponding to the four micro-specimen types (powder volume loading of 62%, 64% and 66%). The simulated shrinkages and relative densities of the sintered micro-specimens are compared to the experimental results indicating a proper agreement

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