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Adel, Norelhayate. "Influence d'un adjuvant proteique sur la texture poreuse et les proprietes mecaniques et thermiques d'un beton cellulaire autoclave." Toulouse 3, 1987. http://www.theses.fr/1987TOU30219.
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Etude en vue de la realisation de murs legers, isolants, homogenes, l'anisotropie de structure pouvant augmenter la resistance vertical et diminuer la conductivite horizontale. Etude de l'effect d'un siliceux, poudre d'aluminium et eau, autoclave a 175**(o)c. Les resultats s'expliquent par la structure dissymetrique vis-a-vis de l'eau des molecules proteiques, hydrophobes d'un cote et hydrofuges de l'autre
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Guillaud, Jean-Philippe. "Qualification décennale d'un autoclave." Paris 5, 1998. http://www.theses.fr/1998PA05P014.
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Habibi, Mohammad Hossein. "Effects of out-time on cure kinetics and rheological properties of out-of-autoclave and autoclave prepregs." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/6819.
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In aerospace applications, multiple rolls of prepreg are often used to manufacture large
parts and the material is kept outside for several days during fabrication. This requirement raises
issues for the fabrication of large parts where stacks of prepreg plies placed on a tool would
remain at room temperature until the rest of the part is laid-up. As such, it is always a concern
that the part's quality could be affected due to the material advancement in curing during outtime
under ambient conditions. Although the reaction is more progressive at an elevated
temperature, extended out-time at a lower temperature could also cause problems, such as a
decrease in tackiness and the processability of prepreg. (Shortened)Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Oliveira, Bruno Pereira de. "Concepção de uma nova plataforma instrumental para esterilização fotônica, química e térmica de instrumento e materiais de uso na saúde." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-21102016-102526/.
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A grande maioria das infecções causadas em ambientes médicos-odontológicas é proveniente de contaminações cruzadas, quando se tem contato entre diferentes instrumentos e /ou aparelhos contaminados após procedimentos médicos. Atualmente o padrão aceito e amplamente utilizado para esterilização de instrumental são os equipamentos chamados de autoclaves, em que é reconhecido e aceito pelos órgãos legisladores. Porém alguns tipos de instrumental e material não podem ser esterilizados utilizando este método tendo uma outra vertente que é aplicação de agentes químicos. Esses criam problemas socioambientais relacionados a sua utilização e descarte. Dessa forma, o objetivo deste trabalho foi desenvolver uma autoclave multifuncional com a utilização de gás ozônio, ultravioleta e calor úmido, em que se testou e analisou microbiológica os protocolos de esterilização, obtendo entendimento e otimização do mesmo. Os resultados mostraram-nos que a configuração desenvolvida atingiu aspectos de esterilidade nos protocolos de esterilização avaliados. Entretanto tem a necessidade de aprofundar estudos aplicando o baixo vácuo para o entendimento quanto a utilização quanto os protocolos do funcionamento e uma futura otimização para produção em larga escala.Most of infection in the medical-dental office is prevenient of cross-contamination, when have the contact with different instrumental and materials without basic control after the process and contact on patient. This point have the standard protocol was accept and described in literature, its utilizing for instrumental sterilizing is the autoclave, it is recognized by organs legislators. However, some instrumental and materials not be accept in this method, on this is necessary one method second in this case is chemical on the instrumentation, but created environmental problem in relation its application. Therefore, this research made the proof of conception in the multifunctional autoclave with the option ozone, ultraviolet and moist heat, what it is analyzing the microbiological protocols of the sterilizing, understanding and optimization the sterilizing process. This results show us which this constructive configuration in this work reached aspects of the sterilizing in the protocols, describe in this text. In the future research in this subject could be study the strongly aspects about the vacuum process before the sterilizing process with ozone gas and development and optimization the prototype for make the scaling up.
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Louis, Bryan Michael. "Gas transport in out-of-autoclave prepreg laminates." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27484.
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Out-of-autoclave (OOA) pre-impregnated (prepreg) materials are a prospective alternative to traditional autoclave processing, with the potential to reduce processing costs and build structures without size limitations imposed by the autoclave. Gas transport pathways in prepreg laminates play an important role in the removal of entrapped gases and volatiles during processing. Removal of gases by vacuum evacuation is essential in order to produce composite laminates with low final void content. Gas pathways are of particular importance in OOA prepregs where the maximum applied pressure during processing is 1 atm.
In this study, the gas transport of OOA prepreg MTM45-1/CF2426A (epoxy/carbon) laminates is examined. The gas permeability of laminates is carefully measured in the in-plane and through-thickness directions. The study examines the effect of the number of layers, the effect of internal ply terminations, and the effects of heat on laminate gas transport. Supplemental experiments such as laminate compaction, microscopy, and water visualization are conducted to gain additional understanding of laminate gas transport.
The study shows that gas transport is strongly directional for the studied prepreg with significantly higher permeability in-plane than in the through-thickness direction. Counter-intuitively, the permeability of MTM45-1/CF2426A is not found to be greater than autoclave prepreg when compared to carbon/epoxy Toray 3900-2 (plain weave). The physical nature of gas transport pathways in MTM45-1/CF2426A prepreg laminates is found to change with processing state. Debulking was found to decrease in-plane gas transport from its as-laid-up permeability. Laminate heating is found to affect laminate gas transport. In-plane permeability decreased with increasing temperature, while through-thickness permeability increased with increasing temperature. Correlations between gas transport and laminate compaction is also evident. During debulking, laminate compaction is found to correlate to decreasing in-plane permeability. Additionally, laminate compaction is found to relate to the quality of edge breathing.
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Cauberghs, Julien. "Out-of-autoclave manufacturing of aerospace representative parts." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106593.
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The use of carbon fibre reinforced composites for aerospace structures has seen a high increase in recent years, and is still growing. The high stiffness-to-weight ratio of these materials makes them ideal for primary structures on airplanes, satellites, and spacecrafts. Nevertheless, the manufacturing of composites remains very costly since it requires equipment investment such as an autoclave, and very qualified workers. Out-of-autoclave manufacturing technology is very promising since it only requires a traditional oven, while still aiming at similar part quality. However, the absence of positive pressure compared with an autoclave makes it more difficult to achieve low porosity parts. This research investigates the manufacturing of complex features with out-of autoclave prepreg technology. The features studied are tight-radius corners with a curvature change, and ply drop-offs. Ply drop-offs tests were conducted to identify if porosity is higher at ply terminations. In corners, the bagging arrangement was modified to achieve the most uniform thickness in areas of curvature change, even with small radii. The conclusions from these studies provided us with guidelines to manufacture larger representative parts, which included these features. The representative parts were tested for porosity, thickness uniformity, mechanical performance, and glass transition temperature(Tg). A total of four representative parts were manufactured with out-of-autoclave technology, and one more was manufactured with an autoclave to allow for a proper comparison between the two processes. The materials used were MTM45-1 5 harness satin and CYCOM5320 plain weave for the out-of-autoclave parts,and CYCOM5276-1 plain weave for the autoclave part. The effect of ply dropoffs on porosity was found to be negligible. Thickness deviation in corners was attributed to a combination of consumable bridging, prepreg's bulk factor and inter-ply shear. Overall, out-of-autoclave prepregs showed performance similar to autoclave prepregs.L'utilisation de matériaux composites en fibres de carbone pour des structures aéronautiques a connu une croissance rapide ces dernières années, et continue de croitre. Le rapport raideur/masse de ce type de matériaux en fait une solution idéale pour les structures primaires d'avions, de satellites, ou de navettes spatiales. Toutefois, la fabrication de ces pièces en composites demeure extrêmement couteuse puisqu'elle nécessite de lourds investissements d'équipement tels que l'acquisition d'un autoclave, ainsi que de la main-d'oeuvre qualifiée. La technologie hors autoclave semble très prometteuse puisqu'elle ne requiert que l'utilisation d'un four traditionnel, tout en visant à obtenir des pièces de qualité similaire. Cependant, l'absence de pression extérieure provenant de l'autoclave rend plus délicate l'obtention de pièces ayant une faible porosité. Cette recherche a pour thème la fabrication d'éléments complexes avec la technologie hors autoclave. Les éléments étudiés sont des angles convexes et concaves ayant de faibles rayons de courbure, ainsi que des plis partiels. Des tests sur les plis partiels ont été réalisés pour déterminer si ils sont associés à une augmentation de la porosité. Dans les angles, l'arrangement des consommables a été modifié pour obtenir l'épaisseur la plus uniforme possible dans les zones de changement de courbure, et cela même pour de faibles rayons. Les conclusions de ces tests nous ont permis de considérer la fabrication de pièces représentatives de plus grande taille, et qui contiennent les éléments précédemment étudiés. Les pièces représentatives ont été testées pour déterminer leur niveau de porosité, l'uniformité de leur épaisseur, leur performance mécanique, et leur température de transition vitreuse. Au total, quatre pièces représentatives ont été fabriquées par technologie hors autoclave, et une a été fabriquée dans un autoclave afin de permettre une comparaison de bon aloi entre ces deux procédés de fabrication. Les matériaux utilisés pour cette recherche étaient du MTM45-1 5 harness satin et du CYCOM5320 plain weave pour les pièces hors autoclave, ainsi que du CYCOM5276-1 plain weave pour la pièce autoclave. La présence de plis partiels n'a pas été associable à une augmentation notable de la porosité. L'uniformité d'épaisseur s'est révélée être une combinaison de pontage des consommables, du facteur de foisonnement du pré-imprégné, et du cisaillement entre les plis de fibre. Globalement, les pré-imprégnés hors autoclave ont montré des performances similaires aux pré-imprégnés autoclave.
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Ghomi, Navid. "Secondary bonded pi-joint out of autoclave process." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121153.
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Composite materials are widely used in the aerospace industry due to their high strength and stiffness properties, as well as the manufacturing possibilities they offer for large components at lower assembly costs. To further lower the manufacturing cost, the use of Out of Autoclave (OOA) process is increasing in popularity. However, mechanically joining parts is a necessary step in the assembly of a large component, driving up the weight of the component and the final assembly cost. A Pi-Joint is one way to offer lower assembly cost through secondary bonding while ensuring the joint's reliability due to the redundancy in the load path. Predicting the failure strength of a bonded joint is essential for the initial stages of aircraft structure design. In this research project, the OOA process is used to manufacture Pi-Joints using pre-impregnated carbon fibre fabric. The Pi-Joint is co-cured with the skin, followed by a secondary bond operation of the web onto the Pi-Joint and skin assembly. To assess the strength of the joint, four different manufacturing techniques are used. In addition, a finite element analysis technique is used to estimate the first mode of failure for the different configurations of the Pi-Joint. The failure strength is correlated with experimental test results to determine the reliability of the manufacturing techniques. Static strength analyses are carried out along with mechanical tests to assess the redundancy of the load path. It is shown in this research that the finite element modelling results are in agreement with the test results.Les matériaux composites sont largement utilisés dans l'industrie aéronautique en raison de leur grande résistance, de leur rigidité, et de leur facilité à être fabriquée en composantes de grandes dimensions à faible coût. Afin de minimiser d'avantage les coûts liés à la fabrication des pièces, le processus de fabrication hors autoclave ou OOA est de plus en plus utilisé. Cependant, l'assemblage mécanique des pièces constitue une étape inévitable de l'assemblage du produit. Ce processus a pour effet d'augmenter le poids et le coût de l'assemblage final. L'utilisation du Joint en Pi qui assemble la structure par un collage secondaire permet de réduire les coûts et d'augmenter la fiabilité du produit final grâce à la multiplicité des chemins de charge qu'il offre. Prédire la défaillance d'un joint collé est essentielle aux phases préliminaires de design des structures primaires d'un avion. Dans ce projet de recherche, le procédé OOA est utilisé afin de fabriquer des joints en composite à base de fibre de carbone. Le Joint en Pi est cocuit avec le revêtement puis une cuisson secondaire permet de joindre l'âme à l'assemblage du Joint en Pi et du revêtement. Afin de déterminer la rigidité du joint, quatre techniques de fabrication sont utilisées. De plus, des analyses par éléments finis sont utilisées afin de prédire le premier mode de défaillance pour diverses configurations du Joint en Pi. La résistance à la défaillance est corrélée avec des résultats de tests expérimentaux afin d'assurer la fiabilité du procédé de fabrication. Des analyses statiques et des tests sont réalisés afin de démontrer la multiplicité du chemin de charge. Dans cette recherche il est montré que les résultats des analyses par élément finis sont en accord avec les résultats des tests.
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Serrano, Léonard. "Systèmes époxyde : cuisson hors autoclave et basse température." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30007/document.
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Les principaux enjeux de la fabrication de pièces en matériaux composites (coût, temps de fabrication, performances,...) sont intimement liés aux moyens de mise en oeuvre, principalement les autoclaves; qui engendrent non seulement des coûts très élevés en termes d'installation et d'entretien, mais limitent également les cadences de production à cause de la longueur des cycles. Afin de réduire cette dépendance, des procédés de fabrication hors autoclave ont été envisagés (Quickstep, Roctool, VARTM, VBO...) entrainant par conséquent des modifications dans la conception des matériaux destinés à ces procédés (cinétique, rhéologie, façon dont sont imprégnées les fibres...). Afin de limiter les changements en termes de procédé de fabrication, de matières premières, de produits d'environnement et de conditions de mise en oeuvre, c'est sur le procédé Vacuum Bag Only que porte cette étude. Plusieurs développement de semi-produits ces dernières années ont permis d'augmenter la robustesse de ce procédé de fabrication, palliant ainsi à cette absence de pression externe durant la cuisson en étuve. Il reste toutefois à démontrer la viabilité de ces produits par rapport à leur mise en oeuvre, à comprendre les mécanismes d'extraction de l'air et à estimer les propriétés mécaniques atteignables par rapport à leur équivalent autoclaveThe main issues concerning composite part manufacturing (cost, manufacturing time, mechanical performances, etc.) are closely linked to the means of curing, mainly autoclaves; which do not only generate very high installation and maintenance costs, but also limit production rates because of the length of the cycles. In order to reduce this dependence, non-autoclave manufacturing processes have been envisaged (Quickstep, Roctool, VARTM, VBO ...) therefore leading to modifications in the design of the materials intended for these processes (including kinetics, rheology, fiber impregnation methods). In order to limit the changes in terms of manufacturing process, raw materials, environment products and implementation conditions, this study is based on the Vacuum Bag Only process. Several semi-product developments in recent years have made it possible to increase the robustness of this manufacturing process, thereby overcoming the lack of external pressure during an oven cure. However, the viability of these products in relation to their implementation still needs to be demonstrated, as well as the understanding of the air removal mechanisms and the estimation of the achievable mechanical properties compared to their autoclave counterpart
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Brillant, Mélanie. "Out-of-autoclave manufacturing of complex shaped composite laminates." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97254.
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Out-of-Autoclave (OOA) manufacturing answers the growing need of the aerospace industry to process components of larger sizes at reduced costs. Recent prepreg materials have been developed specifically for OOA manufacturing and feature increased in-plane permeability through the presence of dry-fibre paths for efficient evacuation of gases. However, the differences in impregnation and resin kinetics attributed to OOA prepregs with respect to autoclave prepregs may affect the compaction behaviour in complex shape laminates. This thesis presents the results of an investigation of important design and processing parameters on the quality of complex shape laminates manufactured by OOA methods.L-shape composite laminates were manufactured by OOA methods, following the recommendations documented in the literature. The samples were tested for thickness variation at the corner and void content levels. The thickness variation at the corner was characterised based on the radius-to-thickness ratio for Cytec Cycom 5320 PW and 8HS prepregs with concave and convex tools. The experimental study showed increased corner thickening with decreasing radius-to-thickness ratio for both tool shapes. The data can be used to determine the minimal radius-to-thickness ratio for acceptable thickness variation for each material and serve as a design guideline. An analytical model of the compaction of L-shape laminates was developed. The discrepancies between the experimental data and the model predictions for thickness variation at the corner highlight the importance of shearing mechanisms in the compaction of L-shape laminates. Also, from the experimental investigation of various bagging arrangements, it is observed that the compaction at the corner is improved with the use of a pressure intensifier or pressure strip with proper corner radius. In addition, breather material should be placed under the pressure intensifier to allow efficient air removal and maintain a low void content level. A numerical analysis of the compaction of a laminate over a concave tool was performed and demonstrated that the material of the pressure intensifier or pressure strip should be of high stiffness for efficient laminate compaction.L'industrie aérospatiale recherche davantage à fabriquer des pièces en matériaux composites de plus grandes dimensions. Ceci peut être accompli à plus faibles coûts par le procédé de fabrication hors-autoclave. Les matériaux pré-imprégnés utilisés pour ce procédé sont semi-imprégnés et donc, dotés d'une section de fibres sèches qui permet l'évacuation des bulles d'air et de gas avant la consolidation du laminé et la polymérisation de la résine. Cependant, le comportement en compaction de ces matériaux sur des moules complexes peut être très différent de celui des matériaux pré-imprégnés pour autoclave, vu le plus faible niveau d'imprégnation et une différente cinétique de réaction de la résine. Cet ouvrage présente les résultats de l'étude de la qualité de pièces complexes fabriquées par le procédé hors-autoclave. L'influence du rayon au coin, de l'épaisseur du laminé ainsi que de la configuration du sac à vide sur l'uniformité de l'épaisseur et le taux de porosité a été étudiée.Des pièces en forme de « L » ont été fabriquées en suivant la méthodologie et les recommendations pour la fabrication hors-autoclave décrites dans la litérature. La variation de l'épaisseur au coin et le taux de porosité ont été mesurés pour chacun des échantillons. La variation de l'épaisseur a été caractérisée en fonction du rapport entre le rayon au coin et l'épaisseur du laminé (R/t), ceci pour deux pré-imprégnés et des moules convexe et concave. Les résutats démontrent une augmentation de la variation de l'épaisseur pour une diminution du rapport R/t. À partir des résultats, pour chaque matériau et pour des fins de conception, il est possible de déterminer le rapport R/t minimum pour une variation de l'épaisseur acceptable. Un modèle analytique de la compaction d'un laminé sur un moule de forme complexe a été dévelopé. La comparaison du modèle avec les résultats expérimentaux permet d'affirmer que les contraintes en cisaillement jouent un rôle important dans la compaction de laminés sur moules complexes. Aussi, l'effet de la configuration du sac à vide et de l'utilisation d'un contre-moule de polymère sur la variation de l'épaisseur et du taux de vide ont été étudiés. Il est observé que le contre-moule augmente la compaction au coin et réduit la variation de l'épaisseur. De plus, pour permettre l'évacuation efficace de l'air, il est important de placer du tissu de drainage sous le contre-moule. Également, l'analyse numérique de la compaction d'un laminé sur un moule convexe a démontré que l'épaisseur est plus uniforme pour un contre-moule de rigidité élevée.
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Kratz, James. "Processing composite sandwich structures using out-of-autoclave technology." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67000.
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Currently, out-of-autoclave (OOA) technology is being used to design and manufacture composite structural components at lower costs. OOA technology enables composites to be produced using only vacuum pressure, eliminating the cost of purchasing and operating an autoclave. The key to OOA prepreg is that they are specially designed to remove air that is entrapped during the lay-up process. The in-plane and through thickness permeability of the prepreg were characterized to determine which bagging configuration would produce the best honeycomb sandwich structure. The bagging configuration that produced the lowest skin porosity was determined to be one ply of non-perforated release film with edge breathing around the perimeter of the panel. The resin content of the prepreg is such that any resin loss from the skin will create dry spots, pinholes, and porosity. The edge breathing allows the air inside the prepreg and core to be removed by the vacuum, and t he non-perforated release film presents resin starvation and subsequently reduces porosity. Caution should be used when debulking out-of-autoclave sandwich panels, since removing all the air from the core reduces the amount of skin compaction available during cure. The skin compaction is needed to suppress void growth, and the optimal internal core pressure was experimentally determined to be between 35-55 kPa. The resin was fully characterized such that when the internal core pressure has reached the optimal range, the resin can flow and close off the air passages. Five representative panels were manufactured using two low temperature cure film adhesives. The optimal curing temperature to minimize porosity of the composite skin was determined to be 100°C. Climbing drum peel tests were used to evaluate the mechanical performance of the panels.Présentement, la technologie hors autoclave (OOA) est utilisée pour la conception et la fabrication à moindre coût des composants structuraux en composite. La technologie OOA permet de produire des composites en utilisant uniquement la pression générés lors des procédés d'ensachage sous vide, en éliminant par le fait même les coûts relatifs à l'achat et à l'exploitation d'un autoclave. L'avantage des matériaux pré-imprégnés destinés à des cuissons hors autoclave est qu'ils sont spécialement conçus pour éliminer les bulles d'air emprisonnées au cours de la préparation. Afin de déterminer la configuration d'ensachage optimale pour la production de structure en sandwich avec noyau en nid d'abeille, l'épaisseur du matériel pré-imprégné ainsi que la perméabilité à travers le plan ont été caractérisées. Les conditions d'ensachage ayant menées à la plus faible porosité correspondent à l'utilisation combinée d'une couche non perforée de pellicule antiadhésive et d'une bordure permettant l'extraction des produits gazeux. La pellicule antiadhésive non perforée permet de prévenir les pertes de résine, tandis que la bordure permettant l'extraction des produits gazeux permet d'évacuer l'air contenu dans le noyau et les couches pré-imprégnés. L'utilisation d'une pellicule non perforée s'est avérée nécessaire puisque la teneur en résine du matériel pré-imprégné est telle que toute perte de résine crée des régions dites sèches (non imprégnée), produit des trous ou défauts à la surface du laminé et augmente la porosité. Il convient d'être prudent lors du dégazage des panneaux en sandwich hors autoclave puisque la suppression de tout l'air contenue dans le noyau réduit le niveau de compaction disponible durant la cuisson. L'application d'une force de compaction adéquate doit être effectuée lors de la cuisson afin de réduire la formation de vide
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PAGANI, A. "Aderência de Revestimento de Argamassa em Bloco de Concreto Celular Autoclavado." Universidade Federal do Espírito Santo, 2012. http://repositorio.ufes.br/handle/10/3937.
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Previous issue date: 2012-05-14O presente trabalho tem por objetivo aprofundar os estudos relativos à aderência de revestimento de argamassa em bloco de concreto celular. Dentre os materiais usados nas vedações, o bloco de concreto celular é o que possui o menor índice de transmitância térmica e a menor densidade, qualificando-o ao uso e, acarretando redução nos custos da estrutura das edificações. Apesar de ser um estudo em laboratório, estaremos procurando soluções que possam ser adotadas em obras, A limpeza do substrato com jato de água para eliminação de poeiras que possam prejudicar a aderência e a cura da argamassa com água. Os traços das argamassas pesquisadas terão uma variação em cada um de seus componentes (cimento, cal e areia) e a água de amassamento será variada com o objetivo de mantermos um mesmo índice de consistência. Após a escolha dos melhores traços que atendam as normas brasileiras, continuaremos a pesquisa com o revestimento de duas paredes com classes de blocos de concreto celular distintos, utilizando mão de obra de um profissional que informará se a trabalhabilidade da argamassa escolhida atende as necessidades do serviço. Concluiremos a pesquisa com uma verificação no Microscópio Eletrônico de Varredura (MEV) das argamassas escolhidas e das que apresentaram os maiores problemas com o objetivo de melhor entendimento da resistência de aderência. Palavras-chaves: Resistência de aderência à tração, argamassa de revestimento, bloco de concreto celular
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Matthews, Samuel Aaron 1962. "High pressure biomass liquefaction in a short-residence time autoclave." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277800.
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The University of Arizona has developed an advanced extruder-feeder biomass liquefaction reactor system. This 11-year project successfully provided an alternative energy process for converting biomass to a crude oil, which can be hydrotreated and ultimately processed into liquid transportation fuels. In order to provide support studies for this process, a short-residence time autoclave capable of providing very brief heat-up and quenching periods in comparison to the time at reaction temperature has been designed and operated. Wood liquefaction in the presence of carbon monoxide, water, and sodium carbonate catalyst has been conducted at residence times of 1.75-60 minutes at temperatures of 340-400°C. Results indicate that the primary thermal decomposition reactions reach completion in less than 1.75 minutes. As a consequence, this research concentrated mostly on the effects of secondary reactions, and even shorter residence times are required to study the primary reactions.
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Jiricek, Joshua A. "Design and modeling of an exhaust gas waste heat autoclave." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40444.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 29).
In order to provide proper sterilization and cleaning of medical equipment for field hospitals and third-world countries while also decreasing the reliance on electricity of traditional sterilization methods, a new steam sterilizer/autoclave system was designed and modeled. This system uses waste engine heat from the exhaust system of a diesel generator set to boil water and produce the pressurized steam conditions necessary for effective medical sterilization. Currently, the design utilizes a 0.59 meter, concentric tube cross-flow heat exchanger and high-temperature heat transfer fluid to draw thermal energy from the exhaust pipe and deposit it into the autoclave pressure vessel to create steam. The system is designed to run a 35-minute sterilization cycle, requiring 15 minutes to produce saturated steam at 2 atmospheres within a 50- liter autoclave, and 20 minutes to sterilize medical instruments in the steam environment. Furthermore, the system uses basic, off-the-shelf fluid transfer materials to provide a robust, effective system that can be easily maintained in the field without need for specialized parts or technicians.
by Joshua A. Jiricek.
S.B.
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Silva, Juliana Lopes. "Modelagem e simulação de reatores autoclave para produção de PEBD." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/60997.
Full textAbstract:
O polietileno de baixa densidade (PEBD) é uma resina termoplástica fabricada através de processos a altas pressões, com reatores do tipo autoclave ou tubular. O cenário atual é de crescente demanda por PEBD produzido a custos competitivos, através de plantas de alto desempenho e capacidade, de modo que o desenvolvimento de processo e produto torna-se um fator chave para as empresas produtoras, sendo os simuladores de processo ferramentas de grande importância para esta finalidade. O objetivo desta dissertação é a implementação de um modelo matemático que represente reatores autoclave de produção de PEBD e a avaliação de sua capacidade preditiva através da comparação dos seus resultados numéricos com dados de literatura e dados de uma planta industrial. O modelo desenvolvido deverá ser capaz de descrever o comportamento do reator, através de seu perfil de temperatura, vazões de iniciador e conversão, e de algumas das principais propriedades do polímero produzido, através de suas massas molares médias. A modelagem dos reatores é composta de compartimentos genéricos de tanque agitado, implementada no simulador dinâmico de processos EMSO, utilizando cinética de literatura. Os balanços de massa e energia foram resolvidos simultaneamente para a obtenção de condições de operação factíveis, sendo necessário o uso de controladores para manter o ponto de operação no estado estacionário desejado. As propriedades são obtidas através da utilização do método dos momentos. É considerada no modelo a possibilidade de formação de duas fases. Parâmetros do modelo cinético e de mistura são ajustados para os dados de planta através de uma rotina de estimação, considerando duas resinas com características de processo e produto distintas. As predições do modelo para perfil de temperatura, vazões de iniciador, conversão e massas molares médias mostraram boa concordância com os dados de literatura e com os dados de planta industrial, para as duas resinas consideradas.The low density polyethylene (LDPE) is a thermoplastic resin manufactured by high pressure processes, with autoclave or tubular type reactors. The present scenario is of growing demand for LDPE produced at competitive costs, through high performance and capacity plants, so that the process and product development becomes a key factor for the producers, and process simulators are high importance tools for this purpose. The objective of this dissertation is the implementation of a mathematical model which represents autoclave reactors for LDPE production and the evaluation of its predictive capacity through the comparison between their numerical results with literature data and with an industrial plant data. The model developed should be able to describe the reactor behavior, through its temperature profile, initiator flows and conversion, and the behavior of some of the main properties of the produced polymer, through their average molecular weights. The reactors modeling is composed of stirred tank generic compartments, implemented in the process dynamic simulator EMSO, using literature kinetics. The mass and energy balances were solved simultaneously in order to obtain feasible operating conditions, which requires the use of controllers to maintain the operating point at the desired steady state. The properties are obtained through the use of the method of moments. It is considered in the model the possibility of formation of two phases. Kinetics and mixture model parameters are fitted to the plant data through an estimation routine, considering two grades with distinct process and product characteristics. The model predictions for temperature profile, initiator flows, conversion and average molecular weights presented good agreement with the literature data and with the industrial plant data, for the two considered grades.
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Wells, Jeremy. "Behaviour of resin voids in out-of-autoclave prepreg processing." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55134.
Full textAbstract:
Resin in prepreg contains small bubbles called resin voids. These voids are isolated from the laminate inter-connected breathing network and cannot be removed by vacuum debulk. Initially these voids contribute negligibly to porosity; however, they may grow and contribute significantly to porosity by vapourization of dissolved volatile species and/or ideal gas expansion particularly in low pressure out-of-autoclave (OOA) processes. Modern advanced prepregs have low volatile content except for moisture due to the hygroscopic property of epoxy. The goal of this study is to investigate the behaviour of resin voids and determine the mechanisms and processing conditions that cause resin void growth. The first part of this study investigates the growth of resin voids in neat resin specimens under controlled temperature, resin pressure and moisture content. Neat resin was vacuum bagged on a glass tool and visually observed in-situ by use of a digital microscope. A criterion that predicts the critical resin pressure below which resin voids can grow due to moisture vapourization was tested for two separate moisture contents and accurately predicts the onset of resin void growth. Additionally, resin voids were observed to contribute significantly to porosity in the very low resin pressure regime due to ideal gas expansion. The results indicate that resin pressure is a critical parameter for mitigating resin void porosity.
The second part of this study investigates resin void growth in laminates by stimulating moisture vapourization and/or ideal gas expansion and comparing them to a porosity free baseline. In order to isolate the effect of resin voids, laminates were fully evacuated before cure. Reduced resin pressure, increased moisture content and increased cure temperature were tested parameters. Laminates were laid up on a glass tool and observed and recorded in-situ. Both surface and bulk porosity were measured for each laminate. In-situ observations and resin pressure correlate well with porosity results based on the resin void growth mechanisms investigated for all test conditions except increased cure temperature. Possible explanations for the discrepancy are discussed. Resin pressure was seen as a critical parameter in porosity management and the concept of a minimum resin pressure is proposed and discussed.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Farhang, Leyla. "Void evolution during processing of out-of-autoclave prepreg laminates." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50674.
Full textAbstract:
Out-of-Autoclave (OOA) prepreg processing is a promising candidate for replacement of autoclave (AC) processing, which is the current standard for manufacturing primary structural parts in the aerospace industry. However, its success is dependent on the ability to produce high quality parts with low porosity. This thesis develops an understanding of porosity in this process by studying the evolution of the voids during processing.
Characterization of voids in partially cured laminates is challenging due to the soft nature of the prepreg matrix. A method for preparation of partially cured samples for optical microscopy and porosity measurement is developed and validated by comparison with results from the ASTM standard density method. It is also shown that thickness can be used to estimate porosity for the no-bleed prepreg system used in this study but that the accuracy is lower than microscopy and density methods.
The evolution of voids during different processing cycles and process conditions was studied using the aforementioned optical microscopy on partially cured laminates made of MTM 45-1/5HS carbon/epoxy prepreg. Fiber tow geometry and gas permeability were also measured to determine fibre tow compaction and the gas transport capability throughout the cure process. It is shown that gas transport, fiber bed compaction and resin infiltration govern void evolution during the process.
Porosity is governed by multiple chemical and transport phenomena, among which gas transport through vacuum evacuation plays a crucial role. An understanding of gas transport in OOA prepreg processing is developed by examining the time scales for gas transport by Darcy flow and molecular diffusion and comparing those to experimental gas permeability and porosity data. Darcy flow is shown to be the primary means of gas removal during the process. The study shows that the dominant direction of gas transport is dependent on the aspect ratio of the laminate, the prepreg material and the processing history as both in-plane and through-thickness permeability vary throughout the cure cycle. Based on these observations, a simple debulk map that gives the minimum recommended room temperature debulk time for OOA laminates as a function of in-plane and through-thickness dimensions is presented.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Araújo, Ana Paula Fernandes. "Tratamento da torta de semente de algodão por autoclavagem e macrofungos para degradação de gossipol." Universidade Federal do Tocantins, 2018. http://hdl.handle.net/11612/980.
Full textAbstract:
A torta de caroço de algodão (TCA) é um coproduto gerado após a extração de óleo
desta oleaginosa, que tem sido utilizada como uma das matérias-primas para a
produção de biodiesel. O uso de TCA na nutrição animal é restrito, sendo mais
utilizado em ruminantes, em função da elevada concentração do fator antinutricional
e tóxico, gossipol. O objetivo do presente estudo foi avaliar a capacidade de alguns
macrofungos em degradar o gossipol na forma livre, utilizando TCA como substrato
após serem esterilizadas por autoclavagem. Trinta e cinco macrofungos foram
avaliados quanto asua capacidade de crescimento em meio à base de TCA e redução
dos teores de gossipol livre (GL). Treze macrofungos apresentaram capacidade de
crescimento micelial em meios de cultura contendo TCA+Agar (placas) ou apenas
TCA (frascos de vidro) como fonte nutritiva. Os seis macrofungos com melhor
desempenho de crescimento foram avaliados quanto à capacidade degradação do GL
em sistema de cultivo por fermentação estado solido (FES). O processo de
esterilização por calor úmido (autoclavagem) do TCAapresentou degradação
significativa do gossipol, entretanto há níveis consideráveis de GL residual na
biomassa.Os seis macrofungos apresentaram capacidade de reduzir até 90% do valor
residual de GL após a autoclavagem das TCAs. O Pleutotus ostreatus CC389 foi
escolhido dentre os seis macrofungos para realização das atividades para
determinação de eficiência biológica e produtividadede cogumelos comestíveis.
Também foram feitas análises das atividades enzimáticas e degradação do GL, nas
biomassas pós-colheita dos cogumelos (SMS, spent mushrom substrate). O P.
ostreatus CC389 quando cultivado em TCA como substrato por 20 dias secretou
enzimas lignolíticas como lacase (até 166,67 UI/mL) e manganês peroxidase (até
12,81 UI/mL). Também degradou o GL residual em até 94% ao final dosvinte dias de
cultivo. A atividade de manganês peroxidase apresentou correlação coma degradação
de GL. A produtividade de cogumelos de P. ostreatus CC389 foi de aproximadamente
20% em quatro formulações de substratos preparados a base de TCA (70%) e 30%
de outras fontes de biomassas vegetais (lignocelulósicos). A eficiência biológica foi
maior na combinação de TCA com serragem de eucalipto (acima de 67%). Os SMSs
e os cogumelos obtidos ao final do sistema de cultivo de P. ostreatusCC389 nas
diferentes formulações apresentaram redução de GL acima de 99%. Os resultados
obtidos nos ensaios com P. ostreatus CC 389 para degradação de GL presentes em
TCA e quando enriquecidas com outras fontes lignocelulosicas poderão servir de elo
para integração de cadeias produtivas de biocombustíveis (biodiesel), fungicultura
(cogumelos comestíveis) e nutrição animal (insumos – enzimas, bioativos, fontes
nutricionais – proteína bruta).Cotton seed cake (TCA, in Portuguese) is a coproduct obtained after the extraction of cottonseed oil, which has been used as one of the raw materials for biodiesel production. TCA is restricted for animal nutrition, being more used for ruminants, due to the high concentration of the antinutritional and toxic factor, gossypol. The objective of the present study was to evaluate the ability of some macrofungi species to degrade free gossypol using TCA as substrates after being sterilized by autoclaving process. Thirty-five macrofungi were evaluated for their growth capacity in medium containing TCA and reduction of free gossypol (GL, in Portuguese). Thirteen macrofungus presented mycelial growth capacity in culture media containing TCA+Agar (Petri plates) or only in TCA (glass bottles) as nutritional source. Six macrofungus with best growth performance were selected and evaluated for GL degradation capacity during solid state fermentation (FES, in Portuguese) system.The humid heat sterilization (autoclaving) of the TCA showed significant degradation of free gossypol, however, there were still considerable levels of residual GL in the biomass. The six macrofungus presented capacity to reduce up to 90% of the residual value of GL in autoclaved TCA. Pleurotus ostreatus CC389 was chosen from among the six macrofungus to determination of biological efficiency and productivity of edible mushrooms. It was also analyzed the enzymatic activities and degradation of GL in post-harvested mushroom biomass (SMS, Spent Mushroom Substrate). P. ostreatus CC389, when cultured in TCA as a substrate for 20 days, secreted lignolytic enzymes such as laccase (up to 166.67 IU/mL) and manganese peroxidase (up to 12.81 IU/mL). It also degraded the residual GL by up to 94% at the end of the cultivation period. The activity of manganese peroxidase showed correlation with the degradation of GL. Mushroom productivity of P. ostreatus CC389 was approximately 20% in four different substrate formulations based on TCA (70%) mixed with 30% of different lignocellulosic biomass sources. The biological efficiency was higher when P. ostreatus CC389 was cultured in substrate containing TCA and eucalyptus sawdust (up to 67%). The SMS and the mushrooms obtained at the end of the P. ostreatus CC389 cultivation in the different formulations presented reduction of GL up to 99%. The results obtained with P. ostreatus CC 389 assays for degradation of GL in TCA and when enriched with other lignocellulosic biomass sources could represent an interesting link for the integration of biofuels (biodiesel), fungiculture (edible mushrooms) and animal nutrition (inputs - enzymes, bioactive molecules, nutritional sources - crude protein) production chains.
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PIMENTEL, André Carlos Silva. "Utilização do farelo de mamona autoclavado na alimentação de codornas em postura." Universidade Federal Rural de Pernambuco, 2013. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6671.
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The experiments were performed in order to evaluate the use of castor meal autoclaved (FMA) in the diet of Japanese quails. Two experiments were conducted. In the first two hundred and ten were selected for quail production and weight uniformity and distributed in a completely randomized design with five treatments and seven replications of six birds each. Which was rated the best level (0, 7, 14, 21 and 28%) of AMF with calcium oxide in diets of Japanese quail during three cycles of 21 days, to characterize the performance and egg quality. The effects of inclusion levels of AMF were evaluated and significant when the averages were compared and evaluated by Tukey test at 5% probability and later regression analysis to determine the best level. For performance parameters, variables, egg production, egg mass and feed conversion by egg mass showed a linear plateau with the inclusion of FMA by 28%. When checked the quality of eggs, variables, egg weight had an effect linear plateau and specific gravity as a linear effect is increased the FMA in the diets and yolk color presented a cubic effect on the participation of the FMA in the rations. Weight data albumen and yolk decreased linearly and weight of albumen and shell percentage one linear plateau with increase in the amount of FMA rations. Levels of up to 7% are recommended for inclusion in diets of laying quails. For the second experiment were selected by two hundred and sixteen quail production and weight uniformity and distributed in a completely randomized design with six treatments and six replicates of six birds each. We evaluated the inclusion of castor autoclaved bran with calcium hydroxide in the level of 21% (FMA21%) with and without enzymatic complexes (EC) and the CE1 consisting of xylanase, β-glucanase, cellulase, pectinase, protease (acting secondary) and CE2 by xylanase, amylase and protease in diets of Japanese quail during three cycles of 21 days, in order to characterize the performance and egg quality. The effects of inclusion levels of AMF were evaluated using analysis of variance and significant when the means were compared by Tukey test at 5% probability. For the performance parameters of feed intake, egg production, egg mass, feed conversion and egg mass per dozen showed no significant differences. The FMA21% to be included in the diet significantly affected egg weight, presenting results similar to the control by adding the CE1. The color and yolk weight data showed higher when added to the diets CE1 FMA21%, the addition of this level of FMA. The results indicate that the addition of 21% of AMF in diets containing enzyme complex with xylanase, β-glucanase, cellulase, pectinase, protease (acting secondary) provides, in the quail posture, perform as well as when fed diets containing corn and soybean meal.
Os experimentos foram realizados com o objetivo de avaliar a utilização do farelo de mamona autoclavado (FMA) na alimentação de codornas japonesas. Dois experimentos foram realizados. No primeiro foram selecionadas duzentas e dez codornas pela produção e uniformidade de peso e distribuídas em um delineamento inteiramente casualizado com cinco tratamentos e sete repetições de seis aves cada. Foi avaliado qual o melhor nível (0, 7, 14, 21 e 28%) de FMA com óxido de cálcio em rações de codornas japonesas em postura, durante três ciclos de 21 dias, para caracterizar o desempenho e a qualidade dos ovos. Os efeitos dos níveis de inclusão de FMA foram avaliados e quando significativo às médias foram comparadas e avaliadas pelo teste de Tukey a 5% de probabilidade e posteriormente análise de regressão para determinar o melhor nível. Para os parâmetros de desempenho, as variáveis, porcentagem de postura, massa de ovo e conversão alimentar por massa de ovo apresentaram um comportamento linear platô com a inclusão de FMA até 28%. Quando verificado a qualidade dos ovos, as variáveis, peso do ovo apresentou um efeito linear platô e a gravidade específica apresentaram efeito linear conforme se aumentava o FMA nas dietas e a cor da gema apresentou um efeito cúbico com a participação do FMA nas rações. Os dados de peso de albúmen e gema diminuíram de forma linear e o peso de albúmen e porcentagem de casca um linear platô conforme aumentava a quantidade de FMA nas rações. Níveis de até 7% são recomendados para a inclusão em dietas de codornas em postura. Para o segundo experimento foram selecionadas duzentas e dezesseis codornas pela produção e uniformidade de peso e distribuídas em um delineamento inteiramente casualizado, com seis tratamentos e seis repetições de seis aves cada. Foi avaliado a inclusão do farelo de mamona autoclavado com hidróxido de cálcio no nível de 21% (FMA21%) sem e com complexos enzimáticos (CE) sendo o CE1 constituído por xilanase, β-glucanase, celulase, pectinase, protease (atuação secundária) e o CE2 por xilanase, amilase e protease, em rações de codornas japonesas em postura, durante três ciclos de 21 dias, com o objetivo de caracterizar o desempenho e a qualidade dos ovos. Os efeitos dos níveis de inclusão de FMA foram avaliados através de análise de variância e quando significativo às médias foram comparadas pelo teste de Tukey a 5% de probabilidade. Para os parâmetros de desempenho variáveis consumo de ração, porcentagem de postura, massa de ovo, conversão alimentar por massa de ovo e por dúzia não apresentaram diferenças significativas. O FMA21% ao ser incluído na ração afetou significamente o peso dos ovos, apresentando resultado semelhante ao testemunha ao adicionar o CE1. A cor e o peso da gema apresentaram dados superiores quando adicionado o CE1 nas dietas com FMA21%, a adição deste nível de FMA. Os resultados indicam que a adição de 21% de FMA em dietas contendo complexo enzimático com xilanase, β-glucanase, celulase, pectinase, protease (atuação secundária) proporciona, às codornas em postura, desempenho tão bom quanto quando alimentadas com dietas contendo milho e farelo de soja.
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SILVA, Juliana Cláudia Neves de Santana. "Farelo de mamona autoclavado na alimentação de suínos e frangos de corte." Universidade Federal Rural de Pernambuco, 2014. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/7000.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Two experiments were made with barrows in order to evaluate the nutritional value of autoclaved castor meal (CMAut.) and the performance of pigs fed with increasing levels of it. The castor meal was produced in biodiesel factory after being washed in ethanol at 80 °C and subsequent drying. In the detoxification routine the following sequential procedures were adopted: mixture of castor meal with 6% of calcium oxide, hydratation in 1:1 proportion, autoclaving at the pressure of 1.23 atm, at 104°C for 90 minutes, and sun drying. Randomized blocks based on the initial weight of the pigs, and one animal per experimental unit were used for the experiments. In the metabolism trial eight barrows with average weight of 40 ± 1.23 kg were used to calculate the apparent metabolizable energy (AME) and corrected AME to nitrogen (AMEn) of the CMAut. Two treatments and four replications were established. The applied diets were one Reference Diet (RD) and one Test Diet with 80% of the RD and 20% of the CMAut. In the performance trial, which lasted 35 days, 25 barrows were used with weight average of 28.1 ± 0.72 kg. Five levels of the CMAut (0, 5, 10, 15 and 20%) were applied with five replicates per treatment for the performance evaluation, and in the end of the experiment, a carcass evaluation was made through ultrasonic measures “in vivo”, and blood samples was taken to biochemical parameters evaluation. It was concluded that the CMAut had an AME value of 2412 kcal/kg and AMEn value of 1937 kcal/kg, and that this alternative ingredient under the presented conditions may be included in diets of pigs in growth at levels up to 20% without affecting performance and carcass evaluation by ultrasound. Blood biochemical parameters proved that the CMAut didn’t present toxic characteristics which caused metabolic dysfunction in the pigs.
Dois experimentos foram realizados com suínos machos castrados para avaliar o valor nutricional do farelo de mamona autoclavado (FMAut.) e o desempenho dos suínos alimentados com níveis crescentes desse farelo. O farelo de mamona foi produzido em usina de biodiesel após lavagem em etanol a temperatura de 80°C. Na destoxicação foram adotados sequencialmente os seguintes procedimentos: mistura de 6% de óxido de cálcio ao farelo, hidratação em proporção 1:1, autoclavagem à pressão de 1,23 atm em temperatura de 104°C por 90 minutos e secagem ao sol. Os experimentos foram realizados utilizando blocos casualizados com base no peso inicial, sendo um animal por unidade experimental. No ensaio de metabolismo foram utilizados oito suínos com peso médio de 40 ± 1,23 kg para determinação da energia metabolizável aparente (EMA) e EMA corrigida para nitrogênio (EMAn) do FMAut. Foram estabelecidos dois tratamentos e quatro repetições. As dietas utilizadas foram uma ração referência (RR) e uma ração teste com 80% da RR e 20% do FMAut. No experimento de desempenho, que durou 35 dias, foram utilizados 25 suínos machos castrados com peso médio de 28,1 ± 0,72 kg. Foram aplicados cinco níveis (0, 5, 10, 15 e 20%) do FMAut. com cinco repetições por tratamento para avaliação do desempenho e no fim do experimento foi realizada avaliação da carcaça através de medidas ultrassônicas in vivo e coleta de sangue para avaliação dos parâmetros bioquímicos. Concluiu-se que o FMAut. apresenta um valor de EMA de 2412 kcal/kg e EMAn de 1937 kcal/kg e que este ingrediente alternativo nas condições de processamentos apresentadas pode ser incluído na ração de suínos em crescimento até o nível de 20% sem prejudicar o desempenho e avaliação de carcaça por ultrassom. Os parâmetros bioquímicos sanguíneos comprovam que o FMAut. não apresenta propriedades tóxicas que causem disfunções metabólicas nos suínos.
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Hsiao, Kevin. "Gas transport and water vapourization in out-of-autoclave prepreg laminates." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42610.
Full textAbstract:
Primary load-bearing aerospace structures have traditionally been manufactured
using autoclave processing. However, recent advances in material technology
have led to the development of pre-impregnated (prepreg) composites that are
designed to be cured out-of-autoclave (OOA) and can potentially reduce the
costs of processing.
In OOA processing, voids are removed by vacuum evacuation through gas
pathways in the prepreg. The availability and interconnectivity of these pathways
determine the prepreg’s gas transport ability. Voids enter into the prepreg via
moisture absorption during storage and physical air entrapment during
manufacturing and material handling. Environmental effects, such as relative
humidity, can alter the moisture content of prepregs and lead to significant
vapour generation during cure. This study examines the gas transport and water
vapourization characteristics of OOA prepreg CYCOM 5320/T650
(epoxy/carbon). Gas permeabilities in the in-plane and through-thickness
directions are measured, and the effects of processing history (debulk time,
temperature etc.) on gas transport are examined. The relationships between
relative humidity, moisture content, and vapour generation are analyzed, and the
use of mass flow sensors for water vapour quantification is validated.
Gas transport is shown to be highly anisotropic in CYCOM 5320/T650, with inplane
gas permeability being three orders of magnitude greater than through thickness. Processing history has a significant effect on permeability, with
extended debulking sessions reducing in-plane permeability by 50%. Increasing
temperature causes in-plane and through-thickness permeabilities to fall.
Microscopy analyses reveal that permeability change is a result of collapsing
voids and resin flow during heating. Moisture content is relatively unaffected by
relative humidity until reaching 30% RH, after which increases in moisture
content become more apparent. Vapourization of absorbed moisture between 0
%RH and ambient conditioned vacuum bagged laminates are similar, suggesting
that under typical process conditions moisture vapourization mainly comes from
the vacuum bag consumables. During vacuum bag processing, vapourization of
absorbed moisture occurs immediately upon heating, peaks around 40 to 60oC,
and then dissipates as heating reaches the hold temperature. The mass flow
sensors are demonstrated to be capable of detecting the onset and termination
of moisture vapourization and quantifying the total mass of water vapourized to
within 10% error.
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Helmus, Rhena [Verfasser]. "Out-of-Autoclave Prepregs: Stochastic Modelling of Void Formation / Rhena Helmus." München : Verlag Dr. Hut, 2016. http://d-nb.info/1115549863/34.
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Cancela, Rodriguez Eva Maria. "Optimization of CFRP components positioning inside the autoclave through CFD simulations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
Carbon fiber reinforced polymers (CFRP) show an excellent balance between thermomechanical properties and low density, leading them to be the material of choice in many applications. In the past years, the use of polymer matrix composites has significantly increased in the aerospace, automotive and naval sectors. Correspondingly, the requirements on high performance and quality keep increasing with the market demand. This generates a big concern on material properties along with the production of a large number of components, minimizing cycles’ time.
This document deals with the optimization of the distribution of composite components inside the autoclave obtaining therefore, the best configuration in order to achieve fair properties in all the elements in the shortest time possible. This study has been done along with the company Eligio Re Fraschini S.p.A., analyzing one of their autoclaves. The aim is to find the best configuration for a given repetitive production.
The optimization procedure that has been followed consisted in, for each of the three different productions considered, assess a set of models representing contrasting scenarios, in order to understand the flow behaviour and find the optimal distribution. The outcomes for the different locations are obtained through simulations performed with Ansys Fluent, a computational fluid dynamic (CFD) software; the ideal configuration is the one maximizing the heat transfer through all the components, in an homogeneous way.
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Ghamlouch, Taleb. "Analysis of convective transfer around simple molds inside a model autoclave." Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4010/document.
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Ces dernières années, l'utilisation de matériaux composites légers et à hautes performances a considérablement augmenté dans de nombreux secteurs industriels. Toutefois, il est évident que le contrôle du champ de température et notamment la minimisation des gradients thermique et de transformation est indispensable à la bonne qualité des pièces. Parmi les différentes méthodes de fabrication existantes, la cuisson des pièces composites par autoclave est largement répandue notamment dans la filière aéronautique. Cette technique permet la réalisation de pièces composites techniques et de grande qualité. Au sein de l’autoclave, les transferts de chaleur sont majoritairement convectifs entre l’ensemble pièce composite plus moule et son environnement. Il s’avère donc nécessaire de connaître (voire d’optimiser) la distribution du coefficient d’échange convectif autour de ces moules. Pour apporter des éléments de réponse à cette problématique, nous présentons dans nos travaux une nouvelle approche consistant à effectuer des mesures expérimentales dans un « autoclave modèle » à échelle réduite, représentatif d’un autoclave industriel. Cet autoclave modèle a été conçu et fabriqué en se basant sur les lois de similitude. L'un des avantages de notre configuration est évidemment la facilité d'utilisation des instruments de mesure non intrusifs et fiables tels que la PIV (Particle Image Velocimetry) pour la mesure du champ de vitesse, et la caméra infrarouge pour la détermination de la distribution des coefficients d’échange autour de moules simples et représentatifs. En parallèle, des modèles numériques qui représentent les configurations d’études expérimentales ont été construits avec le code CFD Ansys Fluent 16©. Les principaux résultats obtenus à partir de ce travail ont montré une distribution non uniforme des coefficients d’échange convectifs autour des moules. Cette hétérogénéité peut conduire à la présence de gradients de température importants au sein des pièces composites fabriquées qui peuvent affecter leur qualité finale. De plus, ces résultats indiquent que le chargement simultané de plusieurs pièces peut engendrer des degrés de cuisson différents entre elles. Cela peut contribuer à la production de pièces composites de qualités différentes. Une étude d’optimisation a conduit de proposer une conception géométrique optimale des supports de moules qui permet à la fois d’intensifier les coefficients d’échange convectifs et de minimiser les hétérogénéités. La comparaison entre les résultats numériques, aérodynamiques et thermiques, et ceux issus des mesures expérimentales a montré un bon accord permettant de valider le code de calculIn recent years, the use of high performance and lightweight composites materials has increased considerably in many industrial sectors. However, the temperature distribution within composite parts produced using the current manufacturing methods plays a key role in determining the parts quality at the end of the process. Among the existing various fabrication methods, the autoclave molding is considered as one of the best methods to manufacture advanced and high quality composite parts. During autoclave molding, heat transfer between the composite parts and the surroundings is strongly coupled with the flow field around their molds and modeled through the convective heat transfer coefficient. The purpose of this study is therefore to develop a new approach for performing experimental measurements in order to analyze the local velocity field and convective heat transfer coefficient distribution around simple and representative industrial molds. The implemented experimental approach is based essentially on the use of a reduced scale autoclave designed thanks to similarity laws, and instrumented by means of non-intrusive measuring instruments such as Particle Image Velocimetry (PIV) and infrared imaging. Furthermore, Computational Fluid Dynamics calculations of the flow field and convective heat transfer were performed using ANSYS Fluent 16.0®. This local investigation has revealed a non-uniform distribution of the convective heat transfer coefficient around the molds. This heterogeneity can directly impact the parts quality during an autoclave process in view of high temperature gradient. Furthermore, the study has shown the presence of shadowing effects during the process of several molds together which can lead to production of composite pieces with different qualities. An optimization study has permitted to propose an optimal geometric design of the supports of the molds that allows the intensification of the convective heat transfer coefficients and the reduction of the heterogeneities. The experimental and the numerical results were in good agreement, leading then to the validation of the performed numerical simulations
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Carboni, Munoz Alvaro Antonio. "Prestressed concrete aerospace autoclave ovens: feasibility and opportunities for the industry." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23456/.
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With the current and future growth of composites in the aeronautic industry, market pressure is increasing for fabricants to obtain the largest possible composite sections, in order to reduce the use weight and complexity of the final product. In this scenario, autoclaves remain as the main constraint to determine the maximum size of a composite element that can be produced and thus, the question on how larger autoclaves can be built is ever more relevant.
This research aims to explore the possibilities, strengths and weaknesses that prestressed concrete presents as a possible material for a new generation of super large autoclaves. To determine the feasibility of the concept, the current state of the art in prestressed structures was studied to determine a viable design scope and the behavior of the structure in key areas, such as fatigue and comparative material consumption. Then, estimations were performed in consideration to the applicable construction codes as well as simplified numerical models, in order to obtain a rough estimate in terms of stresses and material demand.
Finally, a study case was considered for an ultra large autoclave (10m diameter, 84m length) using the previously estimated designs, to study the static and dynamic behavior of the structure.
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Malkki, Pertti. "The manufacturing of uranium nitride for possible use in light water reactors." Licentiate thesis, KTH, Reaktorfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168412.
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Ahmed, Ashraf Uddin. "Resin flow velocity measurement of carbon fiber/epoxy composites in autoclave processing." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5374.
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The resin flow during composite processing affects the mechanical properties and the final dimensions of the part. This study investigates resin flow velocity in autoclave processing. To measure the resin flow velocity during cure, a flow apparatus was designed and manufactured with the ability to follow the autoclave curing cycle. Resin flow tests were conducted on IM7/977-2 unidirectional laminates seeded with fluorescent polymer particles which were tracked during cure. Particle image velocimetry and particle tracking velocimetry techniques were applied individually to obtain resin flow velocity and flow pattern during cure. In addition to the peak resin velocity, corresponding time of peak velocity and flow cessation times were investigated during the test. Moreover, the effect of curing parameters such as heating rate, pressure, vacuum, and isothermal temperature on the resin flow were also studied.
For unidirectional laminate peak resin velocity in longitudinal direction was an order of magnitude higher than the peak velocity in the transverse direction. Experimental results showed that the peak velocity in longitudinal direction was very close to the maximum velocity of the resin flow test. It was observed that resin reached its peak velocity before attaining its minimum viscosity, then slowed significantly before reaching the gel point.
Finally, the resin flow study was further extended for plain weave material. Resin flow was observed in between the tow borders as well as in the tows of the specimen. In regards to plain weave material, resin peak velocities in both longitudinal and transverse directions were of the same order of magnitude.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Vora, Khalil Ur Rehman. "Mechanical properties evolution during cure for out-of-autoclave carbon-epoxy prepregs." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5979.
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Extent of cure and rheological properties were obtained for out-of autoclave materials, Cycom 5320-8HS and Cycom 5320-PW, for the manufacturer recommended cure cycle using Differential Scanning Calorimeter (DSC) and Encapsulated Sample Rheometer (ESR), respectively. Rheological properties from ESR were further used in designing the cure cycles to study the evolution of mechanical properties. Five panels were cured at different cure stages using the designed cure cycles and coupons were tested for short beam shear and combined loading compression properties at different cure stages. To correlate the mechanical properties with its respective glass transition temperature, Dynamic Mechanical Analyzer (DMA) was used to obtain the glass transition temperature for the coupons obtained from the respective panels. Statistical results showed significant difference in short beam shear and combined loading compression properties up to vitrification, however, no significant difference was observed on these mechanical properties after vitrification. The observed linear trend between degree of cure (DOC) and glass transition temperature (Tg) was validated using Dibenedetto relation. Linearly increasing trend between degree of cure (DOC) and glass transition temperature (Tg) for different cure states suggests that both DOC and Tg can be used interchangeably to define the state of material. A good correlation was observed between material cure state and the mechanical properties. A mathematical model was also proposed to determine the short beam shear and combined loading compression properties based on material cure state.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Centea, Timotei. "Material - processing - quality relationships during the consolidation of out-of autoclave prepregs." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116940.
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Out-of-autoclave (OOA) prepreg processing is a new manufacturing method for high performance composites that seeks to reduce costs and increase production flexibility relative to traditional autoclave processing. OOA prepregs may be vacuum bag-only cured in conventional ovens to produce autoclave-quality parts with low void contents. To achieve such quality under vacuum consolidation, OOA prepregs feature dry areas that allow gas evacuation during the early stages of processing but must be subsequently infiltrated with resin. The present thesis describes a four-part investigation into the consolidation of such OOA prepregs, with particular emphasis on flow phenomena and flow-induced defects. First, a novel X-ray computed microtomography approach was successfully used to determine the microstructure of a representative OOA prepreg and track its evolution during processing. The results showed that, initially, the prepreg consisted of dry, micro-porous fibre tow cores surrounded by resin-rich areas and macro-pores, and that two phenomena occurred during processing: the progressive collapse of these macro-pores due to air evacuation at room temperature, and the impregnation of the dry tows at elevated temperature. Second, an analytical model for tow impregnation was developed for three OOA prepregs, and used in a parametric study to evaluate the effect of various material properties and process parameters. The results showed that towimpregnation can successfully occur in a wide variety of cases, but that deviations from ideal situations may lead to incomplete tow impregnation and flow-induced micro-porosity. Third, the effects of cure cycle and out-time on OOA prepreg consolidation were studied experimentally through material characterization, laminate manufacture and microstructural quality analysis. The results demonstrated that out-time had a detrimental effect on resin properties, process phenomena and tow micro-porosity, but that certain cure cycles mitigated or even eliminated such defects. These results were also compared to model predictions, which showed agreement with the observed trends and part quality at low out-times but under-predicted micro-void sizes at very high out-times. Finally, the effects of four deficient consolidation cases (repeated debulks, reduced ambient pressure, reduced vacuum and restricted air evacuation) were studied experimentally by laminate manufacture and final quality evaluation. The results established that reduced ambient pressure, reduced vacuum and restricted air evacuation had specific detrimental effects on consolidation phenomena and on macro- and micro-porosity within the final part, and clarified the allowable extent of such deviations for successful part manufacture. Overall, the thesis contributed to the knowledge on OOA prepreg processing in several ways. First, the key consolidation phenomena that occur during OOA prepreg consolidation were identified. Second, the effect of several material properties, process parameters and deviations from ideal conditions were evaluated to aid process optimization and define the allowable process windows for successful part manufacture. Finally, a new set of experimental and modelling tools were proposed to aid material characterization, process analysis and quality prediction.La mise-en-forme de pré-imprégnés hors-de-l'autoclave est une nouvelle méthode de fabrication de composites haute-performance qui cherche à réduire les coûts et à augmenter la flexibilité par rapport à la fabrication traditionnelle par l'autoclave. Les pré-imprégnés hors-de-l'autoclave peuvent être mis en forme sous un sac à vide, dans un four conventionnel. Pour limiter la porosité, ils comportent des zones sèches qui permettent l'évacuation de gaz au début de la mise-en-forme et qui doivent ensuite être infiltrées par la résine. Cette thèse présente une investigation en quatre parties de la consolidation de tels pré-imprégnés, avec une emphase particulière sur le phénomène et les défauts induits par d'écoulement.En premier lieu, une nouvelle approche basée sur la microtomographie par rayons X a été utilisée avec succès pour déterminer la microstructure initiale d'un pré-imprégné hors-de-l'autoclave typique et pour suivre son évolution pendant la mise-en-forme. Les résultats ont démontré que, initialement, le pré-imprégné était constitué de noyaux de faisceaux de fibres entourés de zones riches en résine et de macro-pores, et que deux phénomènes ont prit place pendant la mise-en-forme: la disparition progressive des macro-pores due à l'évacuation des gaz à température ambiante, et l'imprégnation des faisceaux à températures élevées. En deuxième lieu, un modèle analytique décrivant l'imprégnation des faisceaux à été développé pour trois pré-imprégnés hors-de-l'autoclave, et utilisé pour une étude paramétrique afin d'évaluer l'effet de plusieurs propriétés des matériaux et paramètres de mise-en-forme. Les résultats ont démontré que l'imprégnation des faisceaux peut avoir lieu dans la majorité des cas, mais que des déviations des situations idéales peuvent causer une imprégnation incomplète et de la microporosité induite par l'écoulement. Ensuite, les effets du cycle de température et du temps d'exposition aux conditions ambiantes ont été étudiés par la caractérisation des matériaux, la fabrication de laminés et l'analyse de leur microstructure. Les résultats ont démontré que le temps d'exposition aux conditions ambiantes a un effet néfaste sur les propriétés de la résine, sur les phénomènes prenant lieu durant la mise-en-forme et sur la micro-porosité dans les faisceaux des pièces fabriquées; toutefois, ils ont aussi démontré que certains cycles de température ont mitigé ou même éliminé ces défauts. Ces résultats ont aussi été comparés aux prédictions du modèle, démontrant que ce dernier a capturé les tendances observées, mais qu'il a sous-prédit la taille des micro-porosités pour les cas d'exposition élevée aux conditions ambiantes. Finalement, les effets de quatre cas de consolidation déficiente (l'application de vide répétée, la pression ambiante réduite, le vide réduit et l'évacuation d'air restreinte) ont été étudiés expérimentalement par la mise-en-forme de laminés et l'évaluation de leur qualité. Les résultats ont établi que la pression ambiante réduite, le vide réduit et l'évacuation d'air restreinte ont des effets néfastes spécifiques sur les phénomènes de consolidation et sur la macro- et micro-porosité dans les pièces fabriquées, et clarifié l'ampleur permissible de telles déficiences pour des laminés d'une qualité acceptable. Globalement, cette thèse a contribué à des plus amples connaissances et une meilleure compréhension de la mise-en-forme de pré-imprégnés hors-de-l'autoclave. Premièrement, les principaux phénomènes prenant lieu pendant ce procédé ont été identifiés. Deuxièmement, les effets de plusieurs propriétés des matériaux, paramètres de mise-en-forme et déviations des conditions idéales ont été évalués afin d'aider à l'optimisation et de définir les fenêtres permissibles de variation pour une mise-en-forme réussie. Finalement, de nouvelles méthodes expérimentales et de modélisation ont été proposées pour aider la caractérisation des matériaux, l'analyse de procédés et la prédiction de qualité.
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Schettert, Plinio Gustavo. "Montagem de uma Autoclave e Obtenção de Zircônia Policristal e Quartzo Monocristal." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-21102014-122024/.
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Os cristais do grupo de silicatos, para serem sintetizados no laboratório, requerem alta temperatura e pressão para aumentar sua solubilidade aquosa. Esse processo chamado hidrotermal ou hidrotermico, é realizado num dispositivo denomin ado autoclave. Para estudo de vários silicatos cristalinos naturais brasileiros, como os berilos, os topázios, os espodumênio, os andaluzitas e o próprio quartzo, são necessários cristais \"puros\" para termos de comparação. O presente trabalho ocupou-se com a montagem de uma autoclave, estudar seu funcionamento, segurança do sistema tendo em vista as condições hidrotermais de uma pressão da ordem de 2000 a 2500 atmosferas e temperaturas de 300GRAUSc A 400GRAUSC e, a solubilidade de óxidos de partida para o crescimento de mono ou policristais de tamanhos necessário para a investigação. A autoclave montada operou em 2000 atm. de pressão e 400GRAUC de temperatura por cerca de duas semanas obedecendo as curvas de Kennedy de volume x P x Temperatura. Foram crescidos cristais de quartzo e de zircônia, cujos difratogramas de raio-x mostraram a estrutura cristalina esperada. A fluorescência, micrografia e fotomicroscopia do quartzo revelaram as características esperadasThe crystals of silicate group to be synthesized in laboratory , require very high temperature and pressure , in order to increasethe solubility in water . This process called hydrothermal is carried out in a device named autoclave. The investigation of severa! natural brazilian crystalline silicate such as , beryl , topaz , spodumene , andaluzite and the silica itself , requires , for comparisonsake , nominally pure synthetic crystals . The present work aimed at assembly of an autoclave and examine its operation condition, security precation due to high pressure and temperature of the order of 2000 to 2500 atm and 300 to 400°C , and the analysis of the solubility of oxides used as starting materiais to grow single or polycrystals necessary for investigation . The autoclave produced in the laboratory operated at 2000 atm of pressure and 400°C of temperature during about two weeks. The hydrothermal conditions follow the Kennedy\'s volume vs. temperature curves. Single crystals o f quartz , 2 to 5 mm in size , were obtaimed. X- rays diffraction spectra confirmed their structure . For quartz x -ray fluorescence , SEM micrograph and photomicroscopy revealed to expected features
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Appa, Harish. "Numerical modelling of hydrodynamics, gas dispersion and mass transfer in an autoclave." Doctoral thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/5341.
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Silva, Junior Dorly Fernandes da. "Efeito da composição química sobre as características mecânicas e térmicas do concreto celular autoclavado." Florianópolis, SC, 2011. http://repositorio.ufsc.br/xmlui/handle/123456789/94977.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia de Materiais.Made available in DSpace on 2012-10-25T18:48:02Z (GMT). No. of bitstreams: 1 300576.pdf: 18377818 bytes, checksum: 207e9e6231ede54e39dd6c52f7a2fa23 (MD5)
O concreto celular pode ser entendido como uma espuma cerâmica de poros fechados, fabricada a partir da aeração de uma pasta aquosa de cimento Portland, contendo ou não agregados miúdos, através da incorporação química ou mecânica de um agente formador de poros. Isolamento térmico e acústico, leveza e alta resistência ao fogo são algumas das propriedades que tornam este material muito atrativo para a área de construção civil, onde atualmente é aplicado na substituição de tijolos de alvenarias convencionais. Este projeto ratifica, por meio de planejamentos experimentais (DOE) e outras ferramentas estatísticas, o fator percentual de alumínio como o mais importante para a variação das variáveis respostas densidade, resistência à compressão e coeficiente de condutividade térmica do concreto celular autoclavado. Outros fatores avaliados nos experimentos foram percentuais de vermiculita e de cal e concentração de cimento. Equações lineares que representam as relações entre densidade e resistência à compressão e densidade e coeficiente de condutividade térmica também foram obtidas e propostas neste trabalho. A necessidade de se entender quais outros potenciais de uso do concreto celular na indústria, como por exemplo, isolantes em fornos residenciais e industriais, foi o grande motivador deste estudo.
Cellular concrete is a ceramic foam with closed porous, produced from the aeration of the Portland cement, containing or not small aggregates, via inclusion of a chemical or a mechanical porous agent former. Thermal and acoustic insulation, low weight and high fire resistance are properties that become this material very attractive for building construction applications. This project confirms, thus design of experiments (DOE) and other statistical tools, that the aluminum percentage is the most important factor to the responses density, mechanical strength and thermal conductivity coefficient for the autoclaved cellular concrete. The other factors evaluated in this study were the vermiculite, lime and cement concentrations. Moreover, this project delivers linear equations that correlate density and mechanical strength and density and thermal conductivity coefficient. The need for understanding the potential use of this technology in other industrial areas, like, for example, insulation in home appliances or industrial ovens, was the main motivation of this study.
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Silva, Núñez Sergio Raúl. "Albañilería de Bloques de Hormigón Celular Autoclavado (HCA): Estabilidad Dimensional y Control de Fisuración." Tesis, Universidad de Chile, 2009. http://www.repositorio.uchile.cl/handle/2250/103569.
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El objetivo del presente trabajo es estudiar e investigar el comportamiento mecánico de
las unidades de albañilerías de Hormigón Celular Autoclavado (HCA), buscando
explicar los problemas de fisuración que frecuentemente ocurren en muros y tabiques
construidos con este material. Para esto se realizó un análisis del comportamiento de
las viviendas de albañilería de HCA, construidas en los últimos 15 años en el país,
centrándose especialmente en los problemas constructivos y las patologías recurrentes
que han dado origen a reclamos por parte de los propietarios afectados. Además se
realizó una recopilación de información relevante para el conocimiento y uso de este
material, las normas (nacionales e internacionales) vigentes que rigen la construcción
de este tipo de albañilería.
En este estudio se desarrollaron algunas series de ensayos tendientes a caracterizar el
comportamiento de las unidades de HCA frente a situaciones a las que pueden estar
expuestas las viviendas construidas con este material, evaluándose además una
solución para refuerzo en zonas de concentración de tensiones y para reparación de
fisuras generadas eventualmente en dichas zonas. Para la caracterización de estos
materiales se recurrió tanto a la Norma NCh 2432 Of.99 referida a las especificaciones
de los bloques de HCA, como a la normativa nacional de elementos similares (bloques
de concreto, ladrillos cerámicos, etc.) y a la normativa internacional que cubren los
requerimientos ensayos para el HCA.
A parte de entregar un análisis del comportamiento mecánico de las unidades de HCA
se desarrolló un procedimiento de ensayo para medir las variaciones dimensionales de
las unidades de HCA en ciclos de humedad - secado consecutivos. A partir de los
resultados obtenidos se comprueba que el HCA presenta una variación dimensional
importante, directamente ligada al nivel de humedad absorbida y a su vez se puede
inferir que esta variación aumenta en el tiempo a medida que las albañilerías estén
sujetas a más ciclos de exposición. A partir de éstos resultados se proponen
recomendaciones para el control de la fisuración en albañilerías de HCA, y se plantean
algunas posibles líneas de investigación complementarias para un mejor conocimiento
de este sistema constructivo.
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Vo, Tien Minh. "Cure temperature variation and hygrothermal effects on an out-of-autoclave polymer composite." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5431.
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The effects of cure temperature variation and hygrothermal conditioning on thermal, physical, and mechanical properties of an out-of-autoclave prepreg were investigated and correlated. To study the effects of cure temperature variation, intermediate-cure temperature, second ramp rate, and post-cure temperature were varied from a recommended two-stage cure cycle. The effects of adverse environmental conditions on the cure temperature variation were studied by conditioning the samples in boiling water and a conditioning chamber. The material’s cure state was monitored using a Different Scanning Calorimeter (DSC), Encapsulated Sample Rheometer (ESR), and Dynamic Mechanical Analyzer (DMA). An ultrasonic C-scan and void content tests were performed to map the void distribution in the cured laminates. The mechanical properties were obtained using Short-Beam Shear (SBS) and Combined Loading Compression (CLC) test methods. A further investigation on failure modes was also done on mechanical tested coupons using the photoanalysis method. The results from the ESR and DSC showed that complex viscosity and degree of cure were changed during cure while the final degree of cure, glass transition temperature, and SBS strength did not show significant difference for intermediate-cure temperature ranging from 99oC to 110oC and second-ramp up rate variation ranging from 1.1oC/min to 2.2oC/min. For post-cure temperature variation from 99oC to 143oC, good correlations were obtained between the material’s cure temperatures, state of cure, and mechanical properties for dry room temperature and hot/wet conditions. The study showed that material’s cure state should be used to define and monitor the cure quality rather than using a time-temperature specification.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
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Jośī, Dilīpa. "REAL-TIME DIGITAL CONTROL FOR BIOMASS LIQUEFACTION SYSTEM (HIGH PRESSURE, TEMPERATURE, MICROPROCESSOR, AUTOCLAVE)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275423.
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Cardelli, Freire Claudio. "Estudo da esterilização numa autoclave vertical modificada para o termoprocessamento de bolsas flexiveis." [s.n.], 1992. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255394.
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Orientador : Pilar Rodriguez de MassaquerDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Uma autoclave vertical Dixie de escala pilota (300 L) foi modificada para permitir o tratamento térmico de bolsas esterilizáveis, fis modifíeações envolveram a instalação de uma linha de injeção de ar na tubulação de entrada de vapor, a construção de 10 pratel eiras para o uonfinaííiento de até 30 bolsa de 110 x 150 mm (dimensões internas) e 20 rom de espessura máxima, a instalação de um indicador de nivel de água e de uma tubulação de desaeração. Para simular bolsas contendo alimentos foram construídos blocos de nylon-6 de 15 x 110 x 130 mm. Durante seleção dos meios de aquecimento para bolsas esterilizáveis, foram realizados ensaias de distribuição de calor a 105, 113 e 121º C na mutoclave carregada cosi 30 blocos simuladores utilizando corao meios de aquecimento, vapor puro (meio padrão), misturas vapor/ar com 70 e 90% de vapor e água aquecida com vapor com uma sobrepressão de ar igual utilizada para ab misturas vapor/ar. A temperatura de 121º C permitiu um controle mais estável conduzindo ás melhores distribuições de calor . Para esta temperatura o vapor puro apresentou uma excelente distribuicão de calor com diferenças de temperatura não maiores que 0,6º C cumprindo com o sugerido pela ¿Food and Drug Administration", seguido por mistura com 90 % de vapor, água com sobrepressão a 126 kPa, água com sobrepressão a 191 kPa e mistura com 70 % de vapor. Esta mistura vapor/ar, foi descartada por não ter atingido estabilidade durante o "tempo de processo", com diferenças de temperaturas de até 2º C e ocorrência de pontos frios na metade superior do conjunto de prateleiras. A seleção dos meios de aquecimento Foi completada com ensaios de penetracão de calor a 121º C em blocos simuladores. A penetração de calor dos blocos, em água com sobrapressão a 126 ou 191 kPa foi muito lenta, decorrente do longo tempo de subida. Isto impossibilitou o cálculo das taxas e fatores de atraso do aquecimento (fh e jh, respectivamente). Consequentemente, este meio de aquecimento foi descartado para o estudo da penetração de calor em bolsas no sistema modificado. Não foram detectadas diferenças significativas (a=0,005) nos "fh", "jh", "fc" ou ¿jc¿, de blocos instalados sobre as prateleiras 2 ou 6 processados em vapor puro ou mistura com 90% de vapor. Consequentemente, a mistura com 90% de vapor foi selecionada como o melhor meio de aquecimento para os experimentos com bolsas esterilizáveis. Bolsas contendo 160g de suspensão aquosa de bentonita 10% (p/p) e de 1 a 33 mL de ar residual foram esterilizados 15mín. A 121° C em mistura com 90% de vapor na autoclave modificada. As soldas de fundo e lateral cumpriram com as sugestões s da ¿Food and Drug Administration" referentes à integridade, podendo ser consideradas como de "Alto Desempenho". As bolsas com i a 11 mL de ar residual apresentaram as seguintes características melhor aspecto visual, aquecimento e resfriamento mais rápidos com os menores "fh" e "fc" e o máximo valor de ¿Fo". Porém, quando comparadas com as bolsas contendo de 12 a 33 mL de ar residual estas diferenças não foram significativas (a=0,005)
Abstract: A Dixie vertical retort (pilot size, 300L) was modified for retort pouch sterilization. The modification involved the installation of a line to inject air into the steam inlet Pipe, the construction of a rack with 10 trays confining up to 30 pouches with 110 x 150 mm (internal dimensions) and allowing up to 20 mm of thickness, the installation of a glass sight tube and one stell pipe for venting. Blocks of nylon-6 with 15 x 110 x 150 mm were constructed simulating retort pouches containing foods. Heating media for retort pouches were selected through heat distribution tests at 105, 113 and 121º C in a full retort with 30 simulative blocks heated in the following media. pure steam (as pattern), steam/air mixtures with 70 e 90 % steam and water heated by steam with air overpressure at the same level as steam/air mixtures. Temperature of 121º C allowed the most stable control with the best heat distributions. For this temperature pure steam showed an excellent heat distribution with temperature differences no higher than 0.6° C in agreement with the suggestion of ¿Food and Drug Administration¿, followed by mixture with 90 % steam, water with overpressure at 126 kPa, water with overpressure at 191 kPa and mixture with 70 % steam. This mixture was discarded because it did not achieve stabilization during "processing time", with differences up to 2º C and cold points in the upper half of the rack. Heating media selection was completed with heat penetration tests at 121º C with simulating blocks. Heat penetration m water at 126 and 191 kPa were very slow because of the long come up time, that did not allow the calculation of heating rates and lag factors (fh and jh respectively). Therefore, water was discarded for further heat penetration tests in retort pouches in thy modified retort. No significant differences (a=0,005) among "fh", "jh", "fc" ou "jc" parameters were detected for simulative blocks processed in pure steam or mixture with 90 % steam on tray 2 or 6. Therefore mixtures with 90 % steam were selected as the best heating media for the experiments in retort pouches. Pouches containing 160g of bentonite 10% (w/w) in water and 1 to 33 mL of residual sir were sterilized 15 min at 121º C in mixture with 90% steam m the modified retort. Lateral and bottom seals have attained the recommendation for integrity of the ¿Food and Drug Administration¿ end can be considered as "High Performance" seals. Pouches with 1 to 11 mL of residual air showed the best visual appearance, the fastest heating and cooling with the lower "fh" e "fc" and highest "Fo" value, but if compared against packages with 12 a 33 mL of residual air, these differences were not significatives (a=0,005)
Mestrado
Mestre em Engenharia de Alimentos
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Marques, Luciana Selmi. "Estudo do processamento de compósitos termoplásticos PPS/Carbono obtidos por consolidação em autoclave." Instituto Tecnológico de Aeronáutica, 2010. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1058.
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Usualmente, componentes termoplásticos estruturais são obtidos pela técnica de moldagem por compressão a quente, porém a dimensão da peça é limitada pelo tamanho e capacidade da prensa. Procurando contribuir para ampliar a aplicação de compósitos termoplásticos, pela possibilidade de se fabricar peças maiores e com maior potencial de integração, pelo uso de infraestrutura já disponível em processadores de compósitos, este trabalho aborda o processamento de laminados de poli(sulfeto de fenileno) (PPS) reforçado com fibra de carbono em autoclave, pelo uso de quatro diferentes ciclos de consolidação. Os resultados mostram a viabilidade da consolidação do compósito termoplástico de PPS/fibra de carbono em autoclave, em substituição à moldagem por compressão a quente. Resultados de inspeção por ultrassom revelam que os laminados processados apresentam-se homogêneos e sem descontinuidades. Análises de DSC mostram que as porcentagens de cristalinidade dos laminados variam entre 18-30% em função dos parâmetros de processamento utilizados nos quatro ciclos estudados, sendo que o ciclo com menor taxa de resfriamento (1-5 C/min) favoreceu a maior cristalinidade da matriz polimérica (30%). Resultados dos ensaios mecânicos realizados (compressão, flexão e cisalhamento interlaminar) mostram valores equivalentes aos apresentados na literatura para laminados processados por moldagem por compressão a quente e, também, que as amostras com maior cristalinidade apresentam menor resistência à compressão, uma vez que o maior grau de cristalinidade promove uma maior fragilização da matriz polimérica.
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Rengaraj, Kishen. "Void growth mitigation in high heating rate Out-of-Autoclave processing of composites." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32266/.
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Increased pressure on the transport industry to reduce greenhouse gas emissions has hastened the adoption of high performance composites, particularly in the aerospace industry where the value of weight saving is very high. However, the current method of choice for manufacturing high performance composites (autoclave processing) is not cost effective for processing large (greater than 5m2) structural composite components. Developments in Out-of-Autoclave (OoA) prepreg systems have facilitated the use of vacuum only consolidation pressure to process laminates with autoclave level mechanical properties. However, owing to the low consolidation pressure, the process is heavily dependent on de-bulk quality and low cure temperatures; leading to reduced margin for error as well as long cycle times. In parallel, developments in high heating rate OoA processes have been shown to enable short cure cycle times and autoclave-level mechanical properties; albeit with a high tendency towards porosity. To date, studies on high heating rate OoA processing have been limited and the processes are not well understood. The main objectives of this self-funded study were to understand the mechanism of void growth mitigation in high heating rate OoA processes and to study the feasibility of achieving further reduction in cycle time and cost, whilst maintaining high mechanical properties. The primary mechanism of void growth was identified and an analytical model was used to predict the propensity for void growth during a given cure cycle. The model outcome highlighted a window within the cure cycle during which void growth takes place. It was hypothesised that a reduced time to resin gelation in high heating rate processes can reduce the window for void growth, leading to lower laminate porosity. A novel high heating rate pressurised tooling system (the Pressure Tool) was developed to process laminates at 15oC/min combined with the application of up to 7 Bar hydrostatic pressure. The Pressure Tool was used to verify the hypothesis that reduction in size of the window for void growth, facilitated by high heating rate, can lead to lower laminate porosity. Good agreement was observed between the model outcome and the experimental results. Studies have claimed that the reduction in resin minimise viscosity due to high heating rate can lead to gains in mechanical properties; sometimes even higher than that of autoclave cured laminates. OoA prepregs cured using up to 15oC/min heating combined with up to 3 Bar hydrostatic pressure did not result in the claimed additional gain in mechanical properties. The study confirmed earlier suggestions that additional factors such as void geometry and location within the laminate have to be taken into consideration. The final part of this thesis addresses the physical limitations to high heating rate processes; such as, the effect of tooling material, process ancillaries, laminate thickness and resin kinematics on reducing cure cycle time. The poor thermal characteristics of commonly used process ancillaries limit the dissipation of energy released by the laminate during cure. Due to which, laminate core temperature can exceed by up to 5oC, even if the laminate is processed on a highly conductive tooling material. The optimum tooling material to achieve reductions in cure cycle time whilst minimising laminate core thermal overshoot was found to have a combination of high thermal conductivity and low thermal mass. However, currently used tooling systems are not optimum for achieving further reductions in cycle time, due to unfavourable combination of thermal mass and thermal conductivity. Furthermore, the high reactivity of current resin systems and the inherently poor thermal conductivity of the polymer matrix limits the gains in cure cycle times that can be achieved.
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Rasekh, Ali. "Efficient methods for non-linear thermochemical analysis of composite structures undergoing autoclave processing." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31050.
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Composite structures are increasingly being used in different industries. Their manufacturing
imparts some challenges for the industry: most importantly prediction and control of the
process to specification. The usual numerical solutions typically based on the use of the finite
element analysis are not very suitable for large parts, especially when there is a need for
quick estimation of the results for preliminary design and optimization. Therefore, there is a
need both to have enhanced solutions that reduce the modeling effort for computer
simulation of large and complex structures and also to simplify the solution and provide easy
to use methodologies for quick estimations based on tables and charts.
In the present work, a simple methodology is developed to estimate the temperature
distribution in a thermoset polymer matrix composite slab placed on a tool and subjected to
cycles of temperature ramp and hold leading to the curing of the composite and generation of
heat due to the internal chemical reactions. Supplementary diagrams are also generated to set
limits on the method.
A modified finite element solution for heat transfer is also introduced that reduces the mesh
generation and computational effort. This "higher order shell element" uses enhanced shape
functions and efficient methods for spatial and temporal integrations in order to reduce the
computational run times.
The developed methods provide the design engineer with efficient analysis tools for
predicting the temperature in a composite part. The simple diagrams and tables can be used
for preliminary estimation of the temperature distribution in the part at each stage of the
material development. The enhanced finite element methodology developed here can be used to reduce the amount of effort necessary in mesh generation and refinements necessary to
achieve accurate solutions for thermochemical modelling of complex composite structures
during processing.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Engel, Isabelle. "Validation des autoclaves." Paris 5, 1991. http://www.theses.fr/1991PA05P071.
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Ferraz, Fabiana de Carvalho. "Comparação dos sistemas de alvenaria de vedação: bloco de concreto celular autoclavado x bloco cerâmico." Universidade Federal de Minas Gerais, 2011. http://hdl.handle.net/1843/ISMS-8XDQA8.
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This work intends to compare the sealing masonry systems made with autoclaved aerated concrete block, AACB, with the ones made with ceramic blocks focusing on mechanical aspects. The simple compressive strength of blocks, prisms and walls has been evaluated by means of laboratory tests. In this study, two types of mortar have been evaluated: factory pre-blended mortar and site-dosed mortar with ratio 1:3:8 (cement: lime: sand). The determination of mechanical behavior has been made using the following tests: block compressive strength; prism compressive strength; wall compressive strength; mortar bending tensile strength; mortar axial compressive strength and hard body impact test. AAC blocks with dimensions of 12,5 cm x 30 cm x 60 cm (thickness x height x length), ceramic blocks with dimensions of 14 cm x 19 cm x 29cm (thickness x height x length), industrialized mortar and site-dosed mortar with ratio 1:3:8 (cement: lime: sand) have been used during the tests. AACB system has presented compressive strength higher than the ceramic block system. Using industrialized mortar has shown greaterefficiency and more uniform behavior. AACB system with using of industrialized mortar has presented the best performance among the studied systems regarding the analyzed aspects. AACB system has presented conformity with normative requests regarding the analyzedaspects. The ceramic block system has not presented conformity with normative requests regarding the analyzed aspects.Este trabalho busca comparar os sistemas de alvenaria de vedação feitos com bloco de concreto celular autoclavado, BCCA, com os feitos de bloco cerâmico sob a perspectiva dos aspectos mecânicos. Avaliou-se, por meio de ensaios laboratoriais, a resistência à compressão simples dos blocos, dos prismas e das paredes. Neste estudo foram avaliados dois tipos de argamassa: argamassa industrializada e argamassa dosada em obra com o traço 1:3:8 (cimento:cal:areia). A determinação do comportamento mecânico foi feita por meio dos seguintes ensaios: resistência à compressão dos blocos; resistência à compressão dos prismas; resistência à compressão dasparedes; resistência à tração na flexão da argamassa; resistência à compressão axial da argamassa e impacto de corpo duro. Foram utilizados para os ensaios: blocos CCA de dimensões de 12,5 cm x 30 cm x 60 cm (espessura x altura x comprimento), blocos cerâmicos de dimensões de 14 cm x 19 cm x 29 cm (espessura x altura x comprimento), argamassa industrial e argamassa dosada em obra com o traço 1:3:8 (cimento, cal e areia). O sistema BCCA apresentou resistência à compressão superior ao sistema de bloco cerâmico. A utilização de argamassa industrial nos sistemas estudados mostrou maior eficiência e comportamento mais uniforme em relação à resistência à compressão. O sistema BCCA com a utilização de argamassa industrial apresentou desempenho melhor que os demais sistemas em relação aos aspectos analisados. O sistema BCCA apresentou conformidade com as exigências normativas sob os aspectos analisados. O sistema de bloco cerâmico não apresentou conformidade com as exigências normativas sob os aspectos analisados.
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Viola, Eduardo Spillari. "Efeito do tempo de autoclavagem sobre a digestibilidade dos grãos de soja integral em suínos na fase de crescimento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1996. http://hdl.handle.net/10183/5762.
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Foram conduzidos dois ensaios de metabolismo com suínos em crescimento para avaliar o efeito do tratamento térmico sobre a digestibilidade de grão de soja integral. No ensaio 1 foram utilizados 18 animais distribuídos em 6 dietas, à base de amido de milho e grão de soja, em um arranjo fatorial 3*2, composto por três tratamentos de calor submetidos ao grão (cru, AUTOCLAVADO e AUTOCLAVADO o dobro tempo) e dois níveis de lisina (85 e 100% das exigências do NRC (1988)). No ensaio 2 foram utilizados 18 suínos distribuídos em 18 dietas, à base de amido de milho e grão de soja (autoclavado ou autoclavado o dobro tempo) em um arranjo fatorial 3x3x2, composto por três níveis de lisina (80, 100 e 120% NRC (1988)), três suplementações de aminoácidos (0, metionina e treonina) dois tempos de tratamento térmico (autoclavado e dobro do tempo). No ensaio 1 foi observado efeito do tratamento térmico (P< 0,004) e do nível de lisina (P= 0,009) sobre o ganho de peso e do tratamento térmico (P= 0,006) sobre o consumo de matéria seca. Não foram observados efeitos do tratamento térmico e do nível de lisina sobre os coeficientes de digestibilidade da matéria seca, da proteína e da energia das dietas. No ensaio 2 foi observado efeito do nível de lisina (P= 0,008) sobre a excreção fecal de proteína bruta e de energia bruta (P= 0,003) e do tratamento térmico sobre a excreção fecal da energia bruta (P= 0,04).
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Pinheiro, Maicon. "Infecção hospitalar no sítio cirúrgico: análise dos fatores de risco." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/4088.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis thesis aims to instigate the veterinary community to reflect on the theme, as well as to provide some concepts and information which may help in the diagnosis and also to fight against infection in hospitals, emphasizing the cats and dogs postsurgical infections. To do this, during six months the extrinsic and intrinsic factors related to the infection in cats and dogs in the surgical site in the Veterinary Hospital from the Federal University of Santa Maria (HVU-UFSM) were evaluated. This evaluation is described in the thesis in two papers. In the first paper the autoclave has been checked through chemical and biological tests accomplished every fortnight in the morning; all the tests presented a negative result for the bacterial growth, showing the process of sterilization is efficient. In the second paper the aim was to evaluate the frequency of infection in the surgical site of 156 animals that have underwent surgery at HVU-UFSM, which were submitted to elective and nonelective surgeries of soft tissues and orthopedic ones, without implants. The rate of infection for the surgical site was 1.3% and it is within the limits observed in literature. This way it is possible to conclude that the principles and the procedures used to control surgical infection in this institution are accomplished in an effective way, something that contributes for the low rates of infection in the surgical site.
Esta tese tem por objetivo instigar a comunidade médico veterinária a refletir sobre o tema, assim como disponibilizar conceitos e informações que possam auxiliar no diagnóstico e no combate das infecções hospitalares, com ênfase nas infecções pós-cirúrgicas de cães e gatos. Para isso, foram avaliados durantes seis meses os fatores extrínsecos e intrínsecos relacionados com a infecção no sítio cirúrgico de cães e gatos no Hospital Veterinário Universitário da Universidade Federal de Santa Maria (HVU UFSM). Esta avaliação está descrita na tese em forma de dois artigos. No primeiro artigo verificou-se a eficiência da esterilização por autoclavagem através de testes químicos e biológicos realizados quinzenalmente na primeira carga da manhã; todos os testes realizados geraram resultados negativos para o crescimento bacteriano, demonstrando a eficácia do processo de esterilização. No segundo artigo o objetivo foi avaliar a frequência da infecção no sítio cirúrgico de 156 animais operados na rotina do HVU UFSM, os quais foram submetidos a cirurgias eletivas e não eletivas de tecidos moles e ortopédicas, sem colocação de implantes. A taxa de infecção para o sítio cirúrgico foi de 1,3% e encontra-se dentro dos limites observados na literatura. Dessa forma conclui-se que os princípios e as práticas empregadas para o controle de infecções cirúrgicas nessa instituição, são realizados de maneira efetiva, contribuindo para os baixos índices de infecção no sítio cirúrgico.
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Limousin, Vincent Daniel-Gautier Hélène. "Qualification rétrospective d'un autoclave du laboratoire de contrôle d'un site industriel de production pharmaceutique." [S.l.] : [s.n.], 2003. http://theses.univ-nantes.fr/thesemed/PHlimousin.pdf.
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Cardoso, Débora Regina. "Rotina de monitoração física, química e biológica para estufa e autoclave em consultório odontológico." Centro Federal de Educação Tecnológica do Paraná, 2005. http://repositorio.utfpr.edu.br/jspui/handle/1/89.
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A esterilização de materiais odontológicos é realizada através de autoclaves ou estufas. Para a
utilização desses equipamentos, deve-se seguir diversas orientações estabelecidas pelos
órgãos de saúde competentes. Pelo fato das leis não serem uniformes para todos os órgãos de
saúde, ocorrem divergências com relação à monitoração dos aparelhos de esterilização.
Considerando diversos problemas relatados na literatura e na utilização dos equipamentos, foi
desenvolvida uma rotina de monitoração física, química e biológica para que os cirurgiõesdentistas
possam obter uma maior garantia de que suas autoclaves e estufas estão operando
corretamente e verificar se elas estão sendo eficazes na esterilização dos materiais
odontológicos, atendendo o que estabelece o Ministério da Saúde. Para implementar a rotina,
de acordo com as diretrizes do Ministério da Saúde foram efetuadas monitorações em 12
equipamentos de esterilização (6 autoclaves e 6 estufas), totalizando sete consultórios da
cidade de Curitiba. Os resultados das monitorações mostraram que houve falhas no processo
de esterilização em todos os 12 instrumentos avaliados. A aplicação da rotina mostrou que a
realização das monitorações é fundamental para detectar possíveis falhas de esterilização,
possibilitando um maior controle sobre os materiais odontológicos, reduzindo assim os riscos
de infecção para o paciente e o cirurgião-dentista.Dental instruments can be sterilized by means of autoclave (steam) or kiln (dry heat). In order to utilize these equipment, several directives established by health care governmental organizations must be followed. Since the instructions are not common for all the involved health care organizations, there are some differences considering the monitoring of these equipment. Thus, taking into account several problems found in the literature and in the practical use of the equipment, a monitoring routine covering physical, chemical and biological tests was developed in order to assure that dentists can have their equipment working properly and that they are complying with the directives of the Health Ministry. To implement the routine, 12 sterilization equipment (6 autoclaves and 6 kilns) of 7 dental offices from Curitiba city were monitorized, following the guidelines of the Health Ministry.The results obtained have shown that there were some kind of failure on all 12 tested equipment. Finally, the application of the routine showed that monitoring is critical to detect failures in the sterilization process, therefore the monitoring allows a greater control over dental instruments and reduces the risk of infections for patients and dentists.
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Moretti, Laure. "Simulation des distorsions de cuisson de pièces composites élaborées par co-bonding en autoclave." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2019. http://www.theses.fr/2019EMAC0009.
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Les composites stratifiés en fibres de carbone et à matrices thermodurcissables sont, grâce à leurs propriétés spécifiques, des matériaux très performants pour les pièces de structure primaire en aéronautique. Cependant, durant leur élaboration, de nombreux phénomènes multi-physiques conduisent à l’apparition de contraintes et de déformations résiduelles qui impactent la géométrie finale de la pièce. Ces écarts de géométrie sont critiques pour les pièces de grandes dimensions et les assemblages. Il est donc primordial de prédire ces déformations par la simulation. Le travail effectué au cours de cette thèse s’inscrit au sein du projet MAESTRIA du CORAC porté par la DGAC et dans le cadre d’un partenariat étroit avec Dassault Aviation. La recherche menée s’intéresse plus particulièrement aux assemblages co-collés. Le film de colle époxy utilisé pour ces collages a un comportement propre et risque d’avoir une influence sur les déformations de cuisson des assemblages. La colle, souvent ignorée dans les simulations de cuisson, a donc fait l’objet d’une caractérisation et d’une modélisation propre. Un effort de caractérisation important est fourni afin d’identifier les lois de comportement associées aux variations des propriétés des matériaux au cours de la cuisson. Une fois les lois de comportement matériaux identifiées, la modélisation FEA est implémentée sous Abaqus via des subroutines utilisateurs FORTRAN. Le modèle a ensuite été confronté à des cas expérimentaux. Des mesures de distorsions de plaques, cornières et assemblages sont effectuées. Si le modèle fournit des résultats très satisfaisants pour les pièces composites, les résultats des mesures sur les assemblages révèlent un comportement de l’adhésif plus complexe qu’attendu et une influence non négligeable du film de colle sur les distorsions. La dernière partie de ce travail de recherche se concentre donc sur la compréhension et l’étude approfondie du comportement de ce film de colle. Pour ce faire diverses analyses sont effectuées dont des instrumentations d’assemblages collés par fibres optiques à réseau de Bragg permettant de suivre les déformations in-situ tout au long de la cuissonBecause of their specific properties, composite laminates made of carbon and thermosetting resins are very efficient materials for primary structural parts in aeronautics. However, during their cure, composite parts are subjected to several multi-physical phenomena, which may cause residual stresses and strains that will impact the final geometry of the part. Those variations of geometry are critical for parts of large dimensions and assemblies. Therefore, a simulation tool is needed to predict the cure strains. The work conducted during this Ph.D. is part of the MAESTRIA project of the CORAC supervised by the DGAC and is undertaken as a part of a strong partnership with Dassault Aviation. In this research work a special interest is given to co-bonded assemblies. The epoxy adhesive film used has its own behaviour and may have an influence on cure strains of assemblies. The adhesive, often ignored in cure simulations, is thus subjected to its own characterization and modelling. A significant characterization work is done to identify the behaviour laws of materials throughout their cure. Based on this characterization work, a FEA model is implemented on Abaqus using FORTRAN user subroutines. The model is then compared to experimental measurements for validation. Distortion measurements are done on composite plates, corners and assemblies. The model provides accurate results for composite parts, however, the measurements obtained for assemblies revealed an adhesive behavior more complex than expected and a significant influence of the adhesive film on distortions. Therefore, the last part of this research work focuses on understanding and in-depth studying of the behavior of this adhesive film. To do so, various analyses are carried out, including cure monitoring of co-bonded assemblages by optical fibre grated with Bragg gratings
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Souza, Rafael Gonçalves de. "Estudo de pozolana autoclavada baseada em óxido de cálcio derivado da concha da ostra Crossostrea gigas." Florianópolis, SC, 2008. http://repositorio.ufsc.br/xmlui/handle/123456789/91124.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia de MateriaisMade available in DSpace on 2012-10-23T18:58:09Z (GMT). No. of bitstreams: 1 259882.pdf: 1782093 bytes, checksum: 851ab3198d047e3531f641d7e423813c (MD5)
A região da grande Florianópolis é responsável por 80% da produção nacional de moluscos bivalves entre mexilhões (Perna perna) e ostras (Crassostrea gigas). As fazendas marinhas que produzem tais moluscos têm enfrentado problemas quanto ao destino correto das conchas residuais. Estudos recentes evidenciam que as conchas possuem concentrações superiores a 90% de carbonato de cálcio, podendo ser utilizadas como fonte para a produção da cal [YOON, 2002]. Uma aplicação nobre da cal é a produção de revestimentos cerâmicos autoclavados. O endurecimento de concretos e outros materiais baseados em silicatos de cálcio podem ser acelerados através da cura em vapor a alta pressão. Desta forma, pastas pozolânicas desenvolvem em horas a resistência mecânica que somente seria obtida após dias de cura em temperatura /pressão ambiente Assim foram feitas massas utilizando a cal proveniente da concha de ostra, acrescida de metacaulinita e areia de quartzo em diferentes proporções conformadas por prensagem uniaxial. Após tratamento em autoclave a 200 ºC, foram geradas placas com 40 % de porosidade aproximadamente e com resistência mecânica variando entre 7 a 15 MPa. Valores de condutividade térmica ficaram em torno 0,15 W/mK, semelhante a concretos expandidos para construção civil. Como iniciativa para novas matérias-prima, foram confeccionadas amostras substituindo a metacaulinita por bentonita. Esta troca gerou valores mais elevados no quesito resistência mecânica.
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Magato, James. "Process Model and Sensor Based Optimization of Polyimide Prepreg Compaction During Composite Cure." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1533144776251201.
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Koubaa, Mohamed Ali. "Contribution à la commande prédictive : mise en oeuvre pour le pilotage d'un autoclave de teinture." Lille 1, 1997. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1997/50376-1997-25.pdf.
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La modelisation d'un procede thermique (autoclave de teinture), mettant en jeu de nombreux phenomenes thermomecaniques, conduit a une representation generalement non lineaire complexe difficilement exploitable en vue de la commande. Cependant, la commande predictive a multiples modeles de references permet d'utiliser ce type de representation dans de nombreuses applications industrielles. La propriete essentielle de cette approche a la commande predictive est d'etre capable de controler des processus a modele lineaire et non lineaire, tout en conservant sa robustesse de stabilite deja acquise pour les systemes lineaires. Les elements qui ont permis la synthese d'une telle commande, se resument a: l'utilisation du principe de surechantillonnage. Un ajustement automatique du facteur de ponderation de la commande au cours du fonctionnement du procede. Une mise au point de la methode permettant le choix de la dynamique du systeme global de controle assurant une robustesse de stabilite optimale de la commande. L'utilisation de la programmation non lineaire, afin de minimiser le critere quadratique dans le cas des systemes a modele non lineaire. Nous avons developpe aussi une commande pratique a haut gain. Ce type de commande a l'avantage de controler un systeme a modele mal identifie. La commande a haut gain et la commande predictive a parametre de ponderation auto-ajustable sont implantees sur l'autoclave de teinture afin de le controler en temps reel
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Pernau, Ferrer José Maximiliano. "Evaluación Técnico-Económica de una Planta de Esterilización por Autoclave de Residuos de Naves Marítimas." Tesis, Universidad de Chile, 2008. http://www.repositorio.uchile.cl/handle/2250/104927.
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Elísio, Gonçalo Nuno Nogueira. "Estudo da degradação das propriedades mecânicas de materiais compósitos pelo efeito da esterilização por autoclave." Master's thesis, Universidade da Beira Interior, 2013. http://hdl.handle.net/10400.6/1622.
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A aplicação dos materiais compósitos tem vindo a crescer dia após dia nos mais variados campos, incluindo o campo médico. Neste caso particular, o desenvolvimento de novas técnicas cirúrgicas, implantes ou tratamentos com maior eficiência só são possíveis com um maior conhecimento dos biomateriais existentes, ao nível do seu desempenho em serviço, ou então com o desenvolvimento de novos biomateriais. Contudo, para o seu desempenho em serviço torna-se muitas vezes necessário serem sujeitos a processos de esterilização/desinfeção. O vapor quente sob pressão revela-se, neste caso, o método mais eficaz na esterilização de materiais médico-hospitalares do tipo crítico, devido à sua não toxicidade e de baixo custo. Vulgarmente este tipo de processo é realizado com recurso aos autoclaves.
Neste contexto, o presente trabalho estuda o efeito da esterilização por autoclave na resistência ao impacto de um compósito hibrido carbono/Kevlar/resina epóxi, uma vez que este tipo de carregamento promove reduções significativas da resistência residual à tração, compressão e flexão. O benefício do uso de uma resina reforçada por nanoclays também foi estudado.
Verificou-se que, independentemente do laminado, a esterilização por autoclave diminui a resistência ao impacto destes laminados. A degradação resulta da ação conjunta temperatura/humidade. No entanto, a resina reforçada com nanoclays promove benefícios ao nível da energia restituída e da vida de fadiga. Finalmente estabeleceu-se modelos de previsão com base nas curvas obtidas.The application of composite materials has been growing day by day in various fields, including the medical field. In this particular case, the development of new surgical techniques, implants or treatments with high efficiency are possible only with a better understanding of existing biomaterials, the level of their performance in service, or to the development of new biomaterials. However, for your service performance becomes often necessary to undergo the sterilization processes/disinfection. The hot steam under pressure reveals itself, in this case, the most effective method to sterilize medical and hospital-type critical due to its non-toxicity and low cost. Commonly this kind of process is performed with use of autoclaves. In this context, the present study examines the effect of sterilization by autoclaving in the impact strength of a composite hybrid carbon/Kevlar/epoxy resin, since this type of loading promotes significant reductions in residual resistance to traction, compression and bending. The benefit of using a resin reinforced with nanoclays was also studied. It was observed that, regardless of the laminate sterilization by autoclave decreases the impact resistance of these laminates. The degradation results from the action joint temperature / humidity. However, the resin reinforced with nanoclays promotes benefits in terms of energy restored and fatigue life. Finally settled forecasting models based on the curves obtained.