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1
Tang, Yanyan. "Stereolithography Cure Process Modeling". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7235.
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Although stereolithography (SL) is a remarkable improvement over conventional prototyping production, it is being pushed aggressively for improvements in both speed and resolution. However, it is not clear currently how these two features can be improved simultaneously and what the limits are for such optimization.
In order to address this issue a quantitative SL cure process model is developed which takes into account all the sub-processes involved in SL: exposure, photoinitiation, photopolymerizaion, mass and heat transfer. To parameterize the model, the thermal and physical properties of a model compound system, ethoxylated (4) pentaerythritol tetraacrylate (E4PETeA) with 2,2-dimethoxy-2-phenylacetophenone (DMPA) as initiator, are determined. The free radical photopolymerization kinetics is also characterized by differential photocalorimetry (DPC) and a comprehensive kinetic model parameterized for the model material. The SL process model is then solved using the finite element method in the software package, FEMLAB, and validated by the capability of predicting fabricated part dimensions.
The SL cure process model, also referred to as the degree of cure (DOC) threshold model, simulates the cure behavior during the SL fabrication process, and provides insight into the part building mechanisms. It predicts the cured part dimension within 25% error, while the prediction error of the exposure threshold model currently utilized in SL industry is up to 50%. The DOC threshold model has been used to investigate the effects of material and process parameters on the SL performance properties, such as resolution, speed, maximum temperature rise in the resin bath, and maximum DOC of the green part. The effective factors are identified and parameter optimization is performed, which also provides guidelines for SL material development as well as process and laser improvement.
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Han, Zhao. "Accuracy improvement of stereolithography". Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486424.
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The basic layer-based manufacturing mechanism of stereolithography is built upon a scanning pattern for the entire cross section for each layer. The purpose of this research is to investigate experimentally and theoretically the effects of a new scanning pattern with the aim of improving the dimensional and geometrical performance of Stereolithography against a benchmarked industry standard scanning pattern. The development of the new Bisector scanning patterns is based on the hypothesis that a contour-oriented scanning sequence with more built-in relaxation could provide a more uniform distribution of residual stress caused by the intrinsic phase transformation due to the photopolymerization process. Experiments on a variety of geometries showed that the new scanning pattern offers substantial improvements in terms of dimensional accuracy, part flatness, surface profile and the system running cost. This further insight into the effects of the scanning patterns was gained through the use of Finite Element (FE) modelling. A commercial FE package ABAQUS was employed to develop thermo-mechanical analogous models to ~nalyse and compare the stresses, strains and distortion induced by each pattern. For the Bisector scanning pattern, the scanning direction and length of scanning vectors are more symmetrical distributed in X and Y axes and hence the distortion or curl occurs in both axes and is comparatively less than that observed for the STAR-WEAVE scanning pattern. If the same overall shrinkage is distributed in both axes then the net distortion must be reduced. The modelling results are consistent with the experimental results of this research, in that the amount of distortion on Bisector scanning patterns is less than the STAR-WEAVE scanning pattern.
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Tse, Laam Angela. "MEMS packaging with stereolithography". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17025.
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LeBaut, Yann P. "Thermal aspect of stereolithography molds". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/15991.
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Crawford, Joseph Carlisle-Eric III. "Injection failure of stereolithography molds". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17687.
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Male, John Christie. "Liquid surface measurement in stereolithography". Thesis, Brunel University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343290.
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Fournie, Victor. "Développement d’une bio-imprimante 3D opto-fluidique pour l’impression haute résolution et multimatériaux d’hydrogel". Electronic Thesis or Diss., Toulouse, INSA, 2023. http://www.theses.fr/2023ISAT0057.
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Au cours de cette étude, nous avons introduit un concept novateur d'impression 3D à des fins biologiques. La plateforme 3D-FlowPrint a été conçue pour réaliser des impressions en haute résolution avec plusieurs matériaux. Cette approche vise à pallier les lacunes actuelles des technologies existantes. La micro-extrusion, la stéréolithographie et les sondes microfluidiques ont parfois la capacité d'imprimer des objets hétérogènes, d'imprimer en hautes résolutions ou de précisément manipuler des fluides, mais jamais toutes ces conditions ne sont réunies de manière satisfaisante. La plateforme 3D-FlowPrint adopte un système microfluidique pour acheminer les fluides jusqu'à une tête d'impression immergée, où la solution injectée est photopolymérisée. En dissociant l'apport du matériau de sa polymérisation, cette plateforme parvient à offrir à la fois une haute résolution et la possibilité de travailler avec divers matériaux.Le cœur de cette plateforme réside dans la conception de sa tête d'impression. Cette tête permet l'injection et la récupération des fluides sans contamination de l'environnement, tout en facilitant la transmission de la lumière d'un laser via une fibre optique intégrée. Pour atteindre ces objectifs, nous avons élaboré quatre générations successives de têtes d'impression. La première génération, usinée et moulée, a démontré la faisabilité du concept, mais avait des marges d'amélioration. La deuxième génération, entièrement imprimée en 3D, offrait de nouvelles possibilités géométriques et un prototypage rapide, mais posait des problèmes en matière d'interface optique. La troisième génération, combinant impression 3D et assemblage de matériaux optiquement compatibles, a permis des impressions reproductibles de PEGDA pour développer et caractériser la plateforme. Cependant, cette génération avait des limitations pour l'impression de GelMA. La quatrième génération a surmonté ce problème en introduisant une bulle d'air sous la tête et résolvant ainsi les défis de la troisième génération.Ce manuscrit analyse aussi le système microfluidique en place. Les têtes d'impression fonctionnent en immersion pour autoriser l'impression dans des environnements cellulaires. Ces têtes comprennent un canal d'injection et un canal d'aspiration, ainsi que des reliefs de surface pour assurer la collecte complète de la solution injectée, minimisant la contamination. Via des simulations numériques, des diagrammes de phase ont été établis pour évaluer le taux de récupération du matériau injecté. Ces simulations ont orienté l'optimisation des reliefs de surface pour améliorer les performances des têtes d'impression. De plus, la capacité à changer de fluide au cours d'une impression multimatériaux a été analysée.L'introduction d'une fibre optique dans la tête d’impression a permis la photopolymérisation de la solution injectée. La plateforme a gagné en versatilité avec deux vitesses d'impression grâce à des têtes d'impression imprimées en 3D comprenant deux fibres optiques. Les seuils de photopolymérisation du PEGDA et du GelMA ont été étudiés, et l'impact des flux sur la photopolymérisation a été vérifié. Ces analyses ont abouti à l'impression de structures 2D, 3D et multimatériaux de manière reproductible avec une précision jusqu'à 7 um.En tant que preuve de concept pour des applications biologiques, la plateforme a été utilisée pour quatre approches différentes. Premièrement, des objets en PEGDA inhibent l'adhérence cellulaire sur des parties spécifiques du substrat, permettant d'étudier le développement contraint géométriquement. Deuxièmement, des structures de soutien (scaffold) pour des tissus surfaciques en 3D ont été imprimées. Troisièmement, l'impression de cellules en suspension dans du GelMA a été réalisée ainsi que la caractérisation de la viabilité cellulaire de cette méthode. Finalement, une plateforme hybride a été développée pour la coimpression d'hydrogels et le positionnement de sphéroïdes en trois dimensionsIn this thesis report, we introduce a pioneering concept in 3D printing applied to biological applications. The 3D-FlowPrint platform has been devised to execute high-resolution prints using multiple materials. This approach addresses the current limitations inherent in existing technologies. Micro-extrusion, stereolithography, and microfluidic probes possess individual capabilities to handle heterogeneous objects printing, achieve high resolutions, and manipulate fluids with precision. However, these capabilities have never been fully united in a proper technic. The 3D-FlowPrint platform draws inspiration from each of these concepts. It employs a microfluidic system to channel fluids to a submerged printhead, where the injected solution undergoes photopolymerization. By decoupling material deposition from polymerization, this platform attains both high resolution and the versatility to work with diverse materials.The heart of this platform resides in the design of its printhead. This printhead enables fluid injection and retrieval without environmental contamination, while facilitating laser transmission through an integrated optical fiber. To achieve these goals, we have developed four successive generations of printheads. The first generation, machined and molded, demonstrated the feasibility of the concept but presented room for improvement. The second generation, entirely 3D printed, introduced new geometric possibilities and rapid prototyping but faced challenges with optical interfaces. The third generation combined 3D printing with optically compatible material assembling. It enabled reproducible PEGDA prints to develop and characterize the platform, yet it encountered limitations for GelMA printing. The fourth generation overcame this challenge by introducing an air bubble under the printhead, resolving third-generation issues.This manuscript also analyzes the microfluidic system. The printheads operate immersed, enabling printing in cultured environments. These heads include an injection channel and an aspiration channel, along with surface reliefs ensuring complete collection of the injected solution to minimize contamination. Utilizing finite element-based numerical simulations, phase diagrams have been established to evaluate the material collection capacity. These simulations guided the optimization of surface reliefs to enhance the performance of the printheads. Additionally, the ability to transition from one fluid to another in multi-material printing was analyzed.The introduction of an optical fiber between the microfluidic channels allowed the photopolymerization of the injected solution. The platform gained versatility with dual printing speeds enabled by the insertion of two optical fibers in the 3D printed printheads. Photopolymerization thresholds of PEGDA and GelMA were investigated, and the impact of in-flow photopolymerization was verified. These analyses culminated in the printing of 2D, 2.5D, 3D, and multi-material structures with reproducible precision down to 7 micrometers.Serving as proof of concept for biological applications, the platform was employed in four distinct approaches. First, PEGDA objects prevented cell adhesion on specific part of the substrate, enabling the study of geometrically constrained development. Second, scaffold structures for surfacic 3D tissues were printed. Third, the printing of suspension of cells in GelMA was achieved, along with the characterization of cellular viability using this method. Lastly, a hybrid platform was developed for co-printing hydrogels and positioning 3D spheroids
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D'Urso, Paul Steven. "Stereolithographic biomodelling in surgery /". [St. Lucia, Qld.], 1998. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17881.pdf.
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Liao, Hongmei. "Stereolithography using compositions containing ceramic powders". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27992.pdf.
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Blair, Bryan Micharel. "Post-build processing of stereolithography molds". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19132.
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Marchives, Yoann. "Development of 3D filter made by stereolithography". Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0073/document.
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Les télécommunications sont devenus indispensables dans notre monde actuel. De plus, le volume des données échangées ne cesse de croître. En effet, nous pouvons transmettre nos photos, nos vidéos au monde entier. Nonobstant, nous ne voulons pas attendre pour les avoir, ce qui exige un débit de données très important et par conséquent des signaux avec des bandes passantes plus larges. Les satellites de télécommunications doivent donc s’adapter, c'est pourquoi nous proposons dans ces travaux la recherche de filtre à large bande avec une recherche de compacité et de faibles pertes. Nous nous sommes intéressés à l'utilisation de matériaux céramiques qui permettent d'obtenir de bonnes performances vis à vis de nos besoins. Notre travail est aussi rendu possible par le développement de procédés de fabrication additifs, comme par exemple la stéréolithographie, qui va nous permettre de nous affranchir fortement de règles de dessin contraignantes que nous pourrions avoir en utilisant des procédés classiques. Nous avons développé des filtres avec de larges bandes passantes autour de 4GHz. Une première étude nous a permis de rechercher des concepts qui permettent d'obtenir de forts couplages, conditions sine qua non pour réaliser ces filtres. Plusieurs concepts sont présentés ainsi que leur fabrication et leur mesures. Nous avons ainsi démontré expérimentalement que les concepts proposés, à base de pièces monoblocs céramiques, sont capables de produire des filtres à bandes passantes supérieures à 60 % (voire même 110 % pour une version améliorée)Every day, the data exchanges increase thanks to the new technologies. We can keep our files, our pictures, our videos online to have an access anywhere on the planet (for now). In this way, the data output of the telecommunication systems has to be increased in order to satisfy the more and more demanding users. One way to allow this is to increase the bandwidths of the different signals, making possible to transmit more data at the same time. In this work, we will develop wide bandpass filters dedicated to space telecommunications. For that purpose, we need them to be compact, with low insertion loss and a limited number of parts to assemble. Consequently, we are interested to use resonators made with ceramic materials that permits to reach such properties. Moreover, these materials are compatible with stereolithography, an additive manufacturing process. Such technology is here very useful for our purpose since its design freedom allows the creation of almost all kind of geometries. To realize such wide bandpass filters, we need strong couplings between the different resonators and also for the accesses, so we will present our studies focused on reaching these specific objectives. Then, we will present different designs of wide bandpass filter around 4GHz. After different generation of ceramic based components, we are be able to experimentally create a 60% bandwidth (even 100% for our last version) very compact bandpass filter filling the objectives of this PhD thesis
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Tola, Akale Merid. "Predicting high-speed milling dynamics using stereolithography". Diss., Wichita State University, 2010. http://hdl.handle.net/10057/3659.
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Stereolithographic (SL) models have been successfully utilized during product development and the early stages of process design. In this research, SL models were utilized to predict the natural frequencies of high-speed cutting tools. Most common practices utilize theoretical or numerical methods to evaluate tool designs by using simplifying assumptions. However, these results may fail to accurately predict stability limits of the machining system.
This research developed a proactive approach for evaluating tool design, which minimizes the risk of ordering the wrong tool and sacrificing the most economic machining condition. Experiments have indicated that SL models correlate well with test results performed on actual machining systems. Consequently, SL models of selected tool designs were constructed and utilized to predict the dynamic characteristics and the stability limits of the machining system.
Using stereolithographic models, practitioners can generate stability lobe diagrams and study tool design alternatives before producing or ordering a required tool.Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering
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Reeves, Philip E. "Reducing the surface deviation of stereolithography components". Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/13191/.
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The Stereolithography (SL) process has developed into an accurate method of replicating 3D CAD images into tactile objects used for functions such as product evaluation, preproduction testing or as patterns around which tool cavities can be formed. One of the main limitations with the SL process is the surface roughness of parts resulting from the layer manufacturing process. To-date surface roughness has only been reduced using techniques such as additive coating or abrasive finishing. Research has shown however, that these techniques are both detrimental to the accuracy of parts and can prove to increase the cost of SL parts to the end user. The object of this research is to assess the fundamental cause of surface roughness in layer manufacturing and develop techniques that can be used during the build process to produce SL parts with lower surface deviation. To do this a comparison of the most common commercial RP systems was undertaken to identify the attributes causing surface deviation. From these attributes a mathematical model of layer manufactured surface roughness was developed. Parts manufactured using different SL machines were compared to the mathematical model showing a variety of causes in surface deviation not considered in earlier research, such as layer composition, layer profile and the affects of over curing or print-through on surface deviation. The layer edge profile caused by the shape of the scanning laser also has a significant effect on roughness deviation. However, by using a combination of part orientation and optimal shaped meniscus smoothing, the surface deviation of SL parts was found to be reduced by up to 400% on at least 90- degrees of continuous surfaces. A better understanding of layer manufactured surface roughness has now been achieved and a new smooth build algorithm has been developed.
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Comeau, Benita M. "Fabrication of tissue engineering scaffolds using stereolithography". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26564.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2008.Committee Chair: Henderson, Clilfford; Committee Member: Ludovice, Peter; Committee Member: Meredith, Carson; Committee Member: Prausnitz, Mark; Committee Member: Rosen, David; Committee Member: Wang, Yadong. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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McColl, Erin A. "Using stereolithography to 3D print GelMA hydrogels". Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/109468/1/Erin_McColl_Thesis.pdf.
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The two projects covered by this thesis describe new ways to leverage modern advancements in additive manufacturing techniques in the field of biofabrication. The initial project was a proof-of-principle study which involved the selection, customisation and use of a commercially available stereolithography (SLA) 3D printer to produce synthetic structures using GelMA hydrogels for a cartilage fabrication process. The second topic investigated improving the accuracy, design processes and reproducibility of melt-electrospinning onto a rotating mandrel. This investigation advanced the process from a winding procedure to an accurate 3D printing fabrication method with a particular focus on tubular nerve guide construction.
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Xu, Dun. "Mechanical characterisation of micro-stereolithographic materials". Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/49843/.
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Promising techniques such as micro-stereolithography (MSL) are opening up practical potential for exploiting new ideas for specialized polymer-based Micro-Electromechanical systems (MEMS) through small-batch production. As the field matures and grows, substantial research and commercial development demands better understanding of mechanical properties of MEMS materials to fully explore the potential of this technology. Bulk properties derived from conventional testing of large specimens (at 10 mm order) cannot be trusted. However, small-scale specimens (less than 1 mm) introduce major challenges, such as handling and mounting. The aim of this study was to contribute towards an improved understanding of the mechanical properties of the polymers (MSL materials) with a strong emphasis on developing new metrology. It proposed and described a special form of test-rig and compatible special MSL specimen design. A uniaxial tensile approach was chosen, partly because it offered simpler uncertainty models. The prototype used deadweight loading through a notch flexure, which acted both as a spring in parallel sharing the same displacement with the specimen and as a linear guideway. The specimen was integrally fabricated with large clamping regions and support bars released by cutting. Stiffly constrained mounting and loading surfaces were used to clamp MSL specimens to the flexure, protecting them against parasitic motions during the test in combination. Strain was measured through an elongation measurement by high-sensitivity capacitive micrometry, knowing the specimen dimensions. Verification tests on the clamping conditions showed no significant evidence of sudden slip or creep. MSL specimens were fabricated by a projection-based Envisiontec Perfactory system using a commercial acrylate-based R11 resin. Substantial shrinkage and curl distortion had been observed, which greatly reduced the fabrication accuracy of the MSL specimens. Specimens with different UV exposures and different sizes were fabricated and tested for better understanding of the MSL fabrication process. Typically, Young’s Modulus was a little smaller than expected and certainly dependent on both size and process parameters (in the region studied).
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Davis, Brian Edward. "Characterization and calibration of stereolithography products and processes". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17677.
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Sager, Benay. "A method for understanding and predicting stereolithography resolution". Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/17832.
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Pham, Giang T. "Ejection force modeling for stereolithography injection molding tools". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/18214.
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Rodet, Vincent Fabien. "Tool life and failure mechanisms of stereolithography molds". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/18930.
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Zabti, Mohamed Mohamed. "Effects of light absorber on micro stereolithography parts". Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3646/.
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This thesis reports the results of an investigation of the effects of adding Tinuvin\(\char{msam10}{0x72}\)327 to PIC-100 acrylate resin on such important parameters as cure depth, critical energy, part density, dimension accuracy and surface quality. Initially, an experimental investigation was carried out to characterise the cure depth of resin after the addition of Tinuvin\(\char{msam10}{0x72}\)327 in five different concentrations using a white light microscope. The investigation has shown that increasing Tinuvin\(\char{msam10}{0x72}\)327 concentration reduces cure depth thickness and increases critical energy; it also found that increasing Tinuvin\(\char{msam10}{0x72}\)327 concentration increased the density of the fabricated parts but significantly reduced the tensile strength. The influence of different concentrations of Tinuvin\(\char{msam10}{0x72}\)327 in PIC-100 acrylate resin on the accuracy of the fabricated parts was investigated, and it was shown that increasing the proportion of Tinuvin\(\char{msam10}{0x72}\)327 from 0.1% to 1% (w/w) caused a significant increase in dimensional . The accuracy of Jacobs’ cure depth model in predicting cure depth after the addition of Tinuvin\(\char{msam10}{0x72}\)327 was investigated by comparing measured cure depth and predicted results using Jacobs’ model. The results show that Jacobs’ model does not keep pace with the changes that occur in the PIC-100 photo polymerisation process with changes in material characteristics due to the addition of Tinuvin\(\char{msam10}{0x72}\)327. Jacobs’ cure model was adapted using two empirically derived constants to accurately predict the cure depth. Finally, a parametric optimisation process was performed using the PARETO multi objective optimisation function of Matlab 2010. For 1% Tinuvin\(\char{msam10}{0x72}\)327 concentration and an irradiation level of 750mW/dm\( 2\), the optimum exposure time was found to be 10 seconds.
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Matsushita, Albert Keisuke. "Fabrication of tissue scaffolds using projection micro-stereolithography". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98663.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (page 33).
In vitro liver models are a critical tool in pharmaceutical research, yet standard hepatocyte cultures fail to capture the complexity of in vivo tissue behavior. One of the most critical features of the in vivo liver is the extensive microvasculature which allows for the delivery of nutrients and metabolites without exposing hepatocytes to de-differentiating fluidic shear stresses. A new liver tissue scaffold design able to capture this histological organization may therefore improve the functional longevity of seeded hepatocytes. The additive manufacturing technique of projection micro-stereolithography (PuSL) proved capable of building non-cytotoxic and highly complex 3D structures with microvasculature on the order of 20 um inner diameter. While extensive biological testing remains to be carried out, the built structures reveal much promise in PuSL as a method of tissue scaffold fabrication in terms of in vivo mimicking architecture.
by Albert Keisuke Matsushita.
S.B.
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Simpson, Patrick Glenn. "Additive Manufacturing of Short-Fiber Composites via Stereolithography". Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/29305.
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The effectiveness of using a dual curing system, consisting of a photo and thermal initiator, for the additive manufacturing of carbon fiber short-fiber composites via stereolithography was investigated. The necessary processing parameters were developed that resulted in successful printing and curing of composites at a 5% fiber volume. The effects of layer height and print orientation of the short-fiber composites were evaluated for their effect on the material properties. There was no increase in the flexural modulus or fracture toughness, and a decrease the tensile and flexural strength of the short-fiber composites produced. This was found to be due to weak fiber/matrix interfacial properties, a wide fiber length distribution, and issues with fiber volume consistency. An increase in the tensile modulus was seen and that it could be manipulated with adjustments to layer height and part orientation.Army Research Laboratory (U.S.)
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Yin, Hang. "Fabrication of Tissue-Mimetic Environments Using Projection Stereolithography". Thesis, University of Colorado at Boulder, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10273888.
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The stiffness of an extracellular matrix (ECM) can exert great influence on cellular functions such as proliferation, migration and differentiation. Challenges still remain, however, in the fabrication of artificial ECMs with well-controlled stiffness profiles in three dimension (3D). In this thesis, we developed a projection micro-stereolithography system to fabricate 3D structures with quantitative control over stiffness using biocompatible materials. The technique is based on a grayscale printing method, which spatially controls the crosslinking density in the 3D hydrogel structures without influencing their appearance. Mimetic tissue environments in the form of 2D striped patterns and 3D tubes with stiffness gradients were fabricated. Finally, we seeded bovine pulmonary arterial smooth muscle cells on these engineered environments, and during the culturing, cells migrated to stiffer regions. This work provides a method for fabricating tissue mimetic environments that can benefit the study of cellular behavior and other biomedical research.
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Heger, Matthias. "Entwicklung eines Stereolithographieharzes für elastomere Produkte". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962747858.
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Limaye, Ameya Shankar. "Multi-objective process planning method for Mask Projection Stereolithography". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19717.
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Mask Projection Stereolithography (MPSLA) is a high resolution manufacturing process that builds parts layer by layer in a photopolymer. In this research, a process planning method to fabricate MPSLA parts with constraints on dimensions, surface finish and build time is formulated.
As a part of this dissertation, a MPSLA system is designed and assembled. The irradiance incident on the resin surface when a given bitmap is imaged onto it is modeled as the Irradiance model . This model is used to formulate the Bitmap generation method which generates the bitmap to be imaged onto the resin in order to cure the required layer.
Print-through errors occur in multi-layered builds because of radiation penetrating beyond the intended thickness of a layer, causing unwanted curing. In this research, the print through errors are modeled in terms of the process parameters used to build a multi layered part. To this effect, the Transient layer cure model is formulated, that models the curing of a layer as a transient phenomenon, in which, the rate of radiation attenuation changes continuously during exposure. In addition, the effect of diffusion of radicals and oxygen on the cure depth when discrete exposure doses, as opposed to a single continuous exposure dose, are used to cure layers is quantified. The print through model is used to formulate a process planning method to cure multi-layered parts with accurate vertical dimensions. This method is demonstrated by building a test part on the MPSLA system realized as a part of this research.
A method to improve the surface finish of down facing surfaces by modulating the exposure supplied at the edges of layers cured is formulated and demonstrated on a test part.
The models formulated and validated in this dissertation are used to formulate a process planning method to build MPSLA parts with constraints on dimensions, surface finish and build time. The process planning method is demonstrated by means of a case study.
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Geving, Brad David. "Enhancement of stereolithography technology to support building around inserts". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16799.
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Tucker, Thomas Marshall. "Three dimensional measurement data analysis in stereolithography rapid prototyping". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17082.
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Cedorge, Thomas. "Surface roughness and draft angle effects on stereolithography molds". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18199.
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Jelley, Christopher. "A stereolithography build simulation : business issues and technical development". Thesis, Cranfield University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263534.
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Zhao, Xiayun. "Process planning for thick-film mask projection micro stereolithography". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28097.
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Tonde, Mahesh Pandurang. "Retroffiting a stereolithography system within a laminar flow hood". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Cooke, Malcolm Norman. "Novel Stereolithographic Manufacture of Biodegradable Bone Tissue Scaffolds". Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1088797803.
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Limaye, Ameya Shankar. "Design and Analysis of a Mask projection Micro Stereolithography System". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4943.
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Mask Projection Microstereolithography (MPSLA) is an additive manufacturing process capable for fabricating true three-dimensional microparts and hence, holds promise as a potential micro-fabrication process for micro-machine components. With only a few MPSLA systems developed and studied so far, the research in this field is inchoate and experimental in nature. The process of curing a micropart using an MPSLA system has not been analytically modeled and no literature on process planning for MPSLA is available. In order to employ the MPSLA technology for microfabrication, it is necessary to model its part building process and formulate a process planning method to cure dimensionally accurate microparts.
As a part of this thesis, an MPSLA system is designed and assembled. The process of curing a single layer using this system is analytically modeled as the Layer cure model. The Layer cure model is formulated in two steps. First, the irradiance received by the resin surface is modeled as a function of the system parameters (Irradiance model). Then, the resin used in the system is characterized to experimentally determine its working curve. The Irradiance model and the resin characterization enable us to compute the dimensions of any layer cured using our MPSLA system in terms of the process parameters. The Layer cure model has been validated by curing test layers on our system.
Finally, the Layer cure model has been inverted to formulate a process planning method to cure layers of the required dimensions. Using this process planning method, it is possible to cure layers within a dimensional error of 3%.
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McClurkin, Joel E. "A computer aided build style decision support method for stereolithography". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16684.
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West, Aaron P. "A decision support system for fabrication process planning in stereolithography". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16896.
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Saleh, Naguib. "Effects of humidity and ageing on epoxy-based stereolithography materials". Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/16585.
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In recent years, the use of stereolithography (SL) to produce end-use parts has increased rapidly. However, only limited applications have been considered as there are several problems that impede the conversion of stereolithography to be used as a mainstream manufacturing process. One of the major problems is the instability of the SL parts post-build when subjected to environmental factors. This research included long-term material testing to investigate the effects of ageing, humidity and temperature on the mechanical properties of the SL parts. This work was carried out at a temperature range of -40°C to +100°C over differing ageing and humidity conditions (dry (10%RH), controlled (50%RH) and wet (100%RH)). The results indicated that the main degradation factor was humidity. It was therefore selected for further investigation in this research. This is the most comprehensive analysis and characterisation of materials data yet compiled for additively manufactured materials. Stereolithography materials tested have been shown to significantly degrade over time when subjected to a high level of relative humidity. Therefore, it was the primary aim of this research to identify the mechanism of hygroscopic degradation of epoxy-based SL materials. This was achieved using various techniques including mechanical tests, Differential Scanning Calorimetry (DSC) and Attenuated Total Reflectance (ATR). Modelling of water penetration into SL epoxy-based parts was undertaken and the type of diffusion was found to be anomalous (non-Fickian). Therefore a dual-Fickian model was developed to identify the diffusion coefficients of the investigated materials. Additional equations were developed to model the profiles of moisture concentration and Young's Modulus within a specimen and to predict the stiffuess of an SL material at a certain age. The methodology that has been developed in this work can now be further used to predict the mechanical properties of any future epoxy-based SL material providing the diffusion coefficient(s) of the material are known.
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Campaigne, Earl Andrew III. "Fabrication and Characterization of Carbon Nanocomposite Photopolymers via Projection Stereolithography". Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50270.
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Projection Stereolithography (PSL) is an Additive Manufacturing process that digitally patterns light to selectively expose and layer photopolymer into three dimensional objects. Nanomaterials within the photopolymer are therefore embedded inside fabricated objects. Adding varying concentrations of multi-walled carbon nanotubes (MWCNT) to the photopolymer may allow for the engineering of an objects tensile strength and electric conductivity. This research has two goals (i) the fabrication of three-dimensional structures using PSL and (ii) the material characterization of nanocomposite photopolymers. A morphological matrix design tool was developed and used to categorically analyze published PSL systems. These results were used to justifying design tradeoffs during the design and fabricate of a new PSL system. The developed system has 300μm resolution, 45mm x 25mm fabrication area, 0.23mW/cm2 intensity, and 76.2mm per hour vertical build rate. Nanocomposite materials were created by mixing Objet VeroClear FullCure 810 photopolymer with 0.1, 0.2, and 0.5 weight percent MWCNT using non-localized bath sonication. The curing properties of these nanocomposite mixtures were characterized; adding 0.1 weight-percent MWCNT increases the critical exposure by 10.7% and decreases the depth of penetration by 40.1%. The material strength of these nanocomposites were quantified through tensile testing; adding 0.1 weight-percent MWCNT decreases the tensile stress by 45.89%, the tensile strain by 33.33%, and the elastic modulus by 28.01%. Higher concentrations always had exaggerated effects. Electrical conductivity is only measurable for the 0.5 weight-percent nanocomposite with a 8k/mm resistance. The 0.1 weight-percent nanocomposite was used in the PSL system to fabricate a three-dimensional nanocomposite structure.Master of Science
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Navarrete, Misael. "Three-dimensional electronics packaging integration of stereolithography and direct print". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Harris, Russell A. "Controlling the morphology of parts produced by stereolithography injection moulds". Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/34973.
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The use of stereolithography tools for injection moulding allows plastic parts to be produced in a very short time due to the speed of mould production. The process's greatest advantage is that it can provide a low volume of parts that are produced in the same material and process as parts that would be produced by the conventional hard tooling, but in a fraction of the time and cost. However, this work has demonstrated different rates of polymer shrinkage are developed by parts produced by stereolithography tools and conventional tooling methods. These revelations defy the greatest advantages of the stereolithography injection moulding tooling process—the moulded parts do not replicate parts that would be produced by conventional hard tooling. The aim of this work is to acquire an understanding of the mechanisms in stereolithography tooling that induce these different part properties and develop a modification of the process that could change these, which would allow the moulded parts to demonstrate characteristics like those produced by conventional means.
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SCORDO, GIORGIO. "A novel electrical conductive resin for stereolithographic 3D printing". Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2899751.
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Moore, Chad Andrew. "A multi-axis stereolithography controller with a graphical user interface (GUI)". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16350.
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Kataria, Alok. "Standardization and process planning for building around inserts in stereolithography apparatus". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16653.
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Palmer, Anne Elizabeth. "The effect of feature geometry on the life of stereolithography molds". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18385.
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Brickman, Raredon Micha Sam. "Design and fabrication of physiologic tissue scaffolds using projection-micro-stereolithography". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90086.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.35
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 65-67).
Recent advances in material processing are presenting groundbreaking opportunities for biomedical engineers. Projection-micro-stereolithography, or PuSL, is an additive manufacturing technique in which complex parts are built out of UV-curable resins using ultraviolet light. The primary strength of PuSL is its capacity to translate CAD files into three-dimensional parts with unusually small feature sizes (~0.5 microns). It is an ideal candidate, therefore, for making tissue scaffolds with sophisticated microscopic architecture. Nearly all multicellular biological tissues display a hierarchy of scale. In human tissues, this means that the mechanics and function of an organ are defined by structural organization on multiple levels. Macroscopically, a branching blood supply creates a patent network for nutrient delivery and gas exchange. Microscopically, these vessels spread into capillary beds shaped in an organ-specific orientation and organization, helping to define the functional unit of a given tissue. On a nano-scale, the walls of these capillaries have a tissue-specific structure that selectively mediates the diffusion of nutrients and proteins. To craft a histologically accurate tissue, each of these length scales must be considered and mimicked in a space-filling fashion. In this project, I sought to generate a cellular, degradable tissue scaffolds that mimicked native extracellular matrix across length scales. The research described here lays the groundwork for the generation of degradable, vascularized cell scaffolds that might be used to build architecturally complex multi-cellular tissues suitable for both pharmacological modeling and regenerative medicine.
by Micha Sam Brickman Raredon.
S.M.
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Sphabmixay, Pierre. "Engineering micro-perfusable scaffolds for MesoPhysiological Systems using projection Micro-StereoLithography". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129115.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2020Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 140-155).
MicroPhysiological Systems (MPS) are in vitro models that capture the complexity of human organs at miniature scale by recreating the native microenvironment of resident cells. These systems offer promising alternatives to in vivo animal models for the development of new drugs, disease modeling and biological research. The organs in the human body are continuously perfused via a dense network of blood vessels delivering oxygen, nutrients and biomolecules locally while clearing waste materials produced by the tissue. As a result, MPS that incorporate microperfusion in a three-dimensional format have been a major focal point in the community driving major efforts towards in vitro vascularization methods. A major obstacle to the development of these MPS was the micrometric scale of the human cells forming the building block of any biological system.
But advances in micro and nanofabrication techniques have led to the creation of a myriad of new MPS that allow the successful culture of 3D tissues under microperfusion. Nevertheless, the translation of in vitro data from MPS to clinical data is confronted with the fundamental problem arising from the multi-dimensional scaling of experimental parameters, from micrometric systems to macroscale organs. This thesis describes the design, fabrication and implementation of a MesoPhysiological System (MePS) for the culture of human cells at mescoscopic scale. The MePS consists of a perfusable 3D printed network of microcapillaries serving as a scaffold for the tissue with built-in vasculature. The manufacturing of the MePS was performed using a Projection Micro-StereoLithography Apparatus which enabled the fabrication of centimetric scaffolds with micrometric features at high through-put.
The geometry of the MePS was carefully designed using computational fluid dynamics and computational model of oxygen transport so that critical physico-chemical parameters of the MePS, such as shear forces and oxygen levels would reach physiological values. Long term cultures of liver and brain tissues were performed in the MePS and featured elevated function and viability compared to other MPS. The increased metabolic rate and hepatic function of the liver MePS permitted to recapitulate critical features of metabolic disorders, such as chronic development of an insulin resistance phenotype in type 2 diabetes mellitus.
by Pierre Sphabmixay.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Sabree, Israa. "Fabrication of bioactive glass scaffolds by stereolithography for bone tissue engineering". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/fabrication-of-bioactive-glass-scaffolds-by-stereolithography-for-bone-tissue-engineering(83a17853-1626-4ef2-bb7e-45c07834359c).html.
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Bone tissue engineering aims to regenerate the bone structure and therefore recover the functions of bone tissue rather than replacing it alone. Regenerative medicine focuses on using biomaterials as three-dimensional (3D) porous scaffolds, specifically designed to mimic the nature of host tissue and hence to promote cell growth and tissue regeneration. For such purposes, 3D bioactive glass scaffolds are one of the most studied types of scaffolds for bone tissue engineering because of their excellent bioactivity and potential for stimulating osteogenesis and angiogenesis. In the present study stereolithography has been used to fabricate negative moulds for use with the gel casting process to produce porous 3D 70%SiO2-30%CaO2 bioactive glass-ceramic scaffolds with three different pore sizes and identical porosity. A scaffold with 50 vol. % solid loading suspension was successfully manufactured in two different 3D external shapes and three pore sizes. The bioactive glass powder was crystallized at a temperature of 865.5°C. The mechanical behaviour of the scaffolds sintered at 1200⁰C was found to be influenced by pore size despite the similarity in porosity and the scaffold compressive strength decreased, and the failure probability increased, with increasing pore size. This behaviour was found to be consistent with the predictions of Weibull statistics. All three scaffold types exhibited a compressive strength within the strength range of human trabecular bone. The indentation hardness of the scaffold struts was found to be close to that of cortical bone. In vitro investigation of the scaffolds’ bioactivity was achieved through examining changes in the composition of the immersion solution. Biological tests showed that all scaffolds significantly enhanced cell proliferation, deposition of collagen, alkaline phosphatase activity and the expression of osteocalcin with an increasing rate of mineralisation throughout the culture period; this is believed to be due to the action of released ions from the bioactive glass which induces osteoblast cells from their proliferation phase to a mineralisation stage. A 3D sliced scaffold was produced from an assembly of quasi-2D slices to investigate cell behaviour throughout the scaffold. The goal of in vitro studies of the sliced scaffolds with different pore size is to improve the understanding of how scaffold pore size impacts on initial cell attachment, tissue ingrowth and mass transfer through the scaffold. The results confirmed that a scaffold with bigger pore size provided more space for tissue ingrowth and mass transfer throughout the scaffold over long culture periods. The findings suggest that the fabricated 3D 70%SiO2-30%CaO2 bioactive glass-ceramic scaffolds have potential for use in bone tissue engineering applications.
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Chia, Gomez Laura Piedad. "Elaboration et caractérisation de matériaux fonctionnels pour la stereolithographie biphotonique". Thesis, Mulhouse, 2017. http://www.theses.fr/2017MULH9153.
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La stéréolithographie biphotonique (TPS) est une technique de microfabrication 3D basée sur la polymérisation par absorption biphotonique qui permet d’obtenir en une seule étape des structures 3D complexes avec des détails sub-100nm. Aujourd’hui, en raison des conditions spécifiques de fabrication liées à la TPS (fort flux, confinement spatial de la photoréaction,…), un des enjeux concerne le développement de matériaux fonctionnels compatibles avec ce procédé. Dans ce contexte, l’objectif de cette thèse a été de développer de nouveaux matériaux fonctionnels à base de polymères à empreintes moléculaires (MIP) pour élaborer des capteurs chimiques. Une première partie de ce travail a consisté à mettre en place différentes méthodes dédiées à la caractérisation des propriétés géométriques, chimiques et mécaniques des matériaux élaborés par TPS. Par exemple, la vibrométrie laser a été utilisée pour la première fois afin de sonder de façon non-invasive les propriétés mécaniques de microstructures réalisées par TPS. Dans un second temps, ce travail a été mis à profit pour étudier l’impact du processus de fabrication (i.e. conditions photoniques) ainsi que des paramètres physico-chimiques affectant la photoréaction (i.e. inhibition par oxygène et nature du monomère) sur les propriétés finales des matériaux. Enfin, en s’appuyant sur les résultats obtenus, des microcapteurs chimiques à base de MIP, à lecture optique ou mécanique, ont été fabriqués. Leurs propriétés de reconnaissance moléculaire, ainsi que leurs sélectivités ont été démontrées pour une molécule cible modèle (D-L-Phe)The two-photon stereolithography (TPS) technique is a micro-nanofabrication method based on photopolymerization by two-photon absorption that allows in a single manufacturing step to obtain complex 3D structures with high-resolution details (sub-100nm). Due to the specific conditions of TPS process (intense photon flux, spatial confinement of the photoreaction…) one of the main concerns today is the development of functional materials compatible with the TPS. According to the aforementioned, the general objective of this thesis was to develop new functional materials based on molecularly imprinted polymers (MIP) to elaborate chemical microsensors. In the first step of this work, different methods were implemented to characterize the geometrical, chemical and mechanical properties of the materials synthesized by TPS. For example, laser-Doppler vibrometry was used for first time to evaluate the mechanical properties of microstructures fabricated by TPS in a non-invasive way. In the second step, the characterization methodology was used to study the impact of the manufacturing process (i.e. photonic conditions) and the physicochemical parameters that affect the photoreaction (i.e. oxygen inhibition and the nature of the monomer) and the final properties of the materials. Finally, the obtained results enabled the prototyping of chemical microsensors based on MIP. Their molecular recognition properties and their selectivity were demonstrated for the molecule (D-L-Phe) by an optical and a mechanical sensing method
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Sager, Benay. "Stereolithography Characterization for Surface Finish Improvement: Inverse Design Methods for Process Planning". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04092006-155545/.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Dr. David W. Rosen, Committee Chair ; Dr. Farrokh Mistree, Committee Member ; Dr. W. Jack Lackey, Committee Member ; Dr. Cliff Henderson, Committee Member ; Dr. Ali Adibi, Committee Member.
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Wang, Zongjie. "Development of a visible light stereolithography-based bioprinting system for tissue engineering". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58213.
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Stereolithography-based bioprinting has been considered as a promising solution to generate cell-laden biomaterials for tissue engineering. However, most of the stereolithography-based bioprinting systems employed ultra-violet light to solidify the bioink, a combination of biomaterials and cells. The illumination of ultra-violet light can induce DNA damage and cell cancerization. Therefore, it is safer to utilize non-harmful visible light source for stereolithography-based bioprinting. This thesis presents the design of a simple, low-cost visible light based stereolithography bioprinting system, as well as two novel bioinks supporting visible light solidification. The key features of the developed stereolithography bioprinting system, including the resolution and printing time, were tested. It is found that the low-cost system could reach 60 μm resolution and the printing time for a 100 μm thick layer is less than 4 minutes. The two novel bioinks, named PEGDA-GelMA and GelMA, were characterized to show their mechanical properties and biological compatibility. The PEGDA-GelMA is non cell-adhesive, but with better controllability in its stiffness. The GelMA is relatively soft but cell-adhesive. The system and materials were utilized together in the bioprinting process of NIH-3T3 fibroblast cells. Experimental results show that the cell viability was greater than 85% right after printing. The cells could grow in the bioinks properly for at least five days, proving the feasibility of developed bioprinting solution. Taken together, the developed bioprinting system provides a low-cost visible light stereolithography solution and has the potential to be widely used in tissue engineering applications.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate