Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-08Bitstream added on 2014-06-13T19:58:20Z : No. of bitstreams: 1 silva_lh_me_sjc.pdf: 2510222 bytes, checksum: 9b0884b924775ed48bb9667a27133675 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi desenvolver um novo formato de pilar protético estético em zircônia (3Y-TZP) visando suprimir a utilização do parafuso trespassante utilizado no formato convencional de pilares protéticos em zircônia. Inicialmente foi feita a caracterização do material utilizado na técnica de colagem de barbotina (slip casting) através da confecção de uma barra que teve suas propriedades mecânicas, módulo de elasticidade (E) e coeficiente de Poisson (), grau de contração e dimensão de suas partículas após sinterização avaliados pelos métodos de frequências naturais de vibração e microscopia eletrônica de varredura (MEV), respectivamente. Previamente à confecção do pilar protótipo, este teve seu comportamento mecânico avaliado e comparado a um pilar de 3YTZP convencional com parafuso trespassante pela análise por elementos finitos (FEA) durante sua instalação em implante e recebendo carga oblíqua simulando força de mastigação (210,5 N). O protótipo foi confeccionado pela técnica de colagem de barbotina em um molde de gesso obtido a partir de uma duplicata ampliada em cera. A densidade final foi avaliada pelo método de Archimedes em água. Obteve-se o módulo de elasticidade de 187,97 ± 4,84 GPa e coeficiente de Poisson de 0,19 ± 0,04 para o material. O grau de contração de sinterização foi de 58 vol% e o tamanho do grão foi de 0,705 ± 0,424 μm. Na análise por FEA verificou-se concentrações de tensões na região inicial da rosca para ambos os pilares, e durante o carregamento foram observadas tensões de tração no lado em que incidiu a carga, com presença de tensões de compressão no lado oposto. Ainda, observou-se durante o carregamento do pilar protético convencional concentração de tensão na região do pescoço do parafuso trespassante. A densidade final obtida para o pilar protótipo em 3Y-TZP foi de 95,68% em... / The purpose of this study was to develop a new esthetic zirconia (3YYTZP) implant abutment shape to suppress the use of the fixing screw commonly used by the conventional zirconia abutments. A material characterization, Young’s modulus (E), Poisson’s rate (), shrinkage and particles dimensions after sintering was performed for a bar shape specimen obtained by slip casting evaluated by the natural torsional and flexural vibration frequencies and scanning electron microscope (SEM), respectively. Previously to the prototype abutment confection, its mechanical behavior was evaluated and compared to a conventional zirconia abutment with a fixing screw by finite element analisys (FEA) simulating the abutment installation and oblique loading (210.5 N). The prototype was confectioned by the slip casting technique using a gypsum mould obtained from a wax expanded replica. The abutment had its density measured by Archimedes’ method. Through the natural vibration frequencies a Young’s modulus of 187.97 ± 4.84 GPa and a Poisson’s rate of 0.19 ± 0.04 were obtained for the material. The shrinkage was 58 vol% and the grain size was 0,705 ± 0,424 μm . The FEA showed stress concentration at the first thread pitch for both abutments, and tensile stress concentration were observed at the side that received the oblique load with compressive stress at the opposite side. Whereas, for the conventional abutment model a stress concentration was observed at the screw’s stem. The final density for the zirconia prototype abutment was 95.68% from the theoretical density (6.12 g.cm-3). The zirconia abutment obtained by slip casting presented satisfactory physical properties. The suppressing of the fixing screw could provide better performance to the abutment due to the lack of stress concentration in the screw when an oblique load is applied, when evaluated by FEA

Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-13Bitstream added on 2014-06-13T19:37:34Z : No. of bitstreams: 1 alves_lmn_me_araca.pdf: 553895 bytes, checksum: fdd3818f3f8b58690b7a2926bef25da6 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O êxito clínico nos tratamentos com próteses fixas implanto-suportadas com cantilever é determinado pela maneira como o estresse mecânico é transferido ao implante e ao tecido ósseo circundante sem gerar forças de grande magnitude e pelo estado de saúde dos tecidos adjacentes. Nestes tratamentos, as tensões oclusais se concentram nas extensões distais havendo uma maior incidência de fratura da estrutura, na união entre a prótese e o implante mais distal. Reconhecendo a influência do desenho da estrutura do cantilever sobre os implantes, bem como a necessidade dessas terem formatos que facilitem a higienização e manutenção do tecido periimplantar, o objetivo desse estudo será analisar a relação entre a força aplicada e a deformação ocorrida em barras para cantilever, com áreas de secção transversal em forma de triangulo, quadrada, semi lua, em L e I, através de uma Máquina de Ensaio Universal “EMIC”. Serão confeccionadas 25 barras, em liga de NiCr, divididas em 5 grupos, um para cada formato de barra, com 5 corpos de prova cada um. Uma carga vertical de 200N será aplicada na extremidade do segmento de 15 mm, com velocidade de 0,5mm por minuto. As barras que suportaram uma maior carga foram as em formato quadrado, seguida pela meia lua, L, triangular sendo a em formato de I a que suporta menor força de mordida. Houve diferenças estatisticamente significantes quando comparadas as em formato quadrado em relação às outras formas e as em meia lua também com as outras formas, sendo que as em formato de L, I e triangular não apresentaram diferenças estatisticamente significantes. É importante definirmos corretamente o formato da secção transversal da barra do cantilever de uma prótese, em função de sua relação com a classe de prótese antagônica, para que não haja deformação durante a função proporcionando estruturas leves, confortáveis e com espaço suficiente para higienização / The clinical success in treatment with implant-supported fixed prostheses with cantilever is determined by how the mechanical stress is transferred to the implant and the surrounding bone without generating forces of great magnitude and the health of tissues. In these treatments, the occlusal stress focus on the distal extensions and a higher incidence of fracture of the structure, the bond between the prosthesis and the most distal implant. Recognizing the influence of the cantilever design of the structure on implants, and the need to have these formats to facilitate the cleaning and maintenance of peri-implant tissue, the aim of this study will examine the relationship between the applied force and deformation occurred in bars for cantilever with areas of cross section in the shape of triangle, square, half moon, L and I, through a Universal Testing Machine EMIC. 25 bars will be made in NiCr, divided into five groups, one for each bar shape, with five specimens each. 200N of a vertical load is applied at the end of the segment of 15mm with a speed of 0.5 mm per minute. The bars that bore a greater burden were square in shape, then the half moon, L, and the triangular-shaped supports that I less bite force. There were statistically significant differences when comparing the square in shape relative to other forms and in a half-moon also with other forms, and the L-shaped, triangle and I did not show statistically significant differences. It is important to properly define the shape of the cross section bar of the cantilever of a prosthesis, because of its relationship with the class of prosthesis antagonistic, so that no deformation during function, providing lightweight structures, comfortable with enough space for cleaning

Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-07Bitstream added on 2014-06-13T20:37:53Z : No. of bitstreams: 1 zequetto_mm_me_araca.pdf: 764308 bytes, checksum: f9f1ab6ade3df1b1023440b60d0137eb (MD5) / Pro-Line Servicos Produtos Odontologicos Ortopedicos Ltda. / O presente trabalho avaliou a desadaptação marginal de infra-estruturas metálicas de coroas metalo-cerâmicas obtidas com técnicas de fundição convencional (T1) e rápida (T2), utilizando para inclusão os revestimentos: aglutinado por fosfato Termocast (R1) e a base de cerâmica granulada Micro Fine 1700 (R2), confeccionando padrões em cera escultura Galileo (P1) e padrões em resina acrílica Duralay (P2), com n=56, sobre um troquel metálico. Para a construção dos padrões, utilizou-se uma matriz de silicone e realizou-se a fundição com liga de Ni-Cr. Verificou-se a desadaptação marginal por meio de um microscópio comparador digital Mitutoyo em 12 diferentes pontos de cada infra-estrutura. Os dados obtidos foram submetidos à análise de variância (ANOVA) e teste de Tukey com p<0.05, demonstrando os menores valores de desadaptação marginal e, estatisticamente similares (p<0.05), em ordem crescente, para os grupos: P2R2T2 (55,4æm), P2R1T2 (55,6æm), P2R1T1 (57,4æm), P1R2T2 (59,4æm), P1R2T1 (86æm), P1R1T1(104,4æm); e os maiores valores para P1R1T2 (166,9æm) e P2R2T1 (185,3æm). Os resultados obtidos permitiram concluir que as infra-estruturas metálicas obtidas com padrões, tanto de cera quanto de resina acrílica, apresentaram valores aceitáveis em ambas as técnicas de fundição realizadas, desde que as interações e recomendações dos fabricantes dos revestimentos sejam respeitadas. / The present study evaluated the marginal unfit of metallic infrastructures of metallic-ceramic crowns obtained through the conventional (T1) and accelerated (T2) casting techniques, using for investing the investments: agglutinated by phosphate Termocast (R1) and the base of granulated ceramic Micro Fine 1700 (R2), making patterns in sculpture wax Galileo (P1) and patterns in acrylic resin Duralay (P2), with n=56, on a metallic die with shoulder in chamfer. For the construction of the patterns, a matrix of silicone was used and the casting was made with Ni-Cr alloy. The marginal unfit was verified through the comparing microscope Mitutoyo in 12 different points of each infrastructure. The values obtained were submitted to analysis of variance (ANOVA) and Tukey s test with p<0.05, showed smaller values and statistically similar, in increasing order, for the groups: P2R2T2 (55,4ìm), P2R1T2 (55,6ìm), P2R1T1 (57,4ìm), P1R2T2 (59,4ìm), P1R2T1 (86ìm), P1R1T1(104,4ìm); and the largest values for P1R1T2 (166,9ìm) and P2R2T1 (185,3ìm). Taking obtained results into account, it was possible to conclude that the metallic infrastructures obtained from patterns, of wax as well as of acrylic resin, presented acceptable values of marginal fit in both casting techniques, providing the interactions and the recommendations of the investments manufacturers are respected.

Dissertation Abstract Abdominalaortic aneurysm (AAA) is a serious disease. Its prevalence is in the developed countries about 3%. As an aneurysm is considered a dilatation of all layers of a vessel wall over 3 cm. Majority of AAA are small and asymptomatic, and although the risk of rupture increases with the size of aneurysm sack, even the small aneurysms rupture. The rupture mortaliry ranges about 70 %. Surgical treatment is indicated in the asymptomatic patients in diameter of AAA over 5 cm. The average speed of growth of AAA is 0.3 cm per year, e.g. in the early diagnosed patients there is a several years interval for a pharmacolocical influencing of the progression of this disease. Knowledge of pathogenesis is essential for any targeted pharmacological treatment. Our prospective, non-randomised studies are based on the application of the stereological methods for the histopathological assessment of the AAA samples. The acquired data enable the statistical analysis, including the null hypothesis testing. In our study analyzing the histopathology of AAA aortae of 65 patients (65 walls and 55 thrombi) and 6 normal abdominal aortae from the organ donors we assessed the following parameters: the area fractions of collagen and elastin, and the length density of elastin in intima and media, the area...

La réduction de la masse des véhicules, notamment des Groupes Motopropulseurs contribue à la réduction des émissions polluantes. Aujourd’hui afin d’aboutir à cet objectif, la conception de pièces automobiles (Carter Mécanisme, Carter Cylindre) en matériau allégé tel que l’aluminium et ses alliages est en plein essor. Pour la production de grande série, ces alliages sont mis en œuvre par le procédé de fonderie ‘’Aluminium sous pression’’.Ce procédé utilise des moules métalliques. La maîtrise du comportement thermique du moule : chauffage, refroidissement interne (par circuit) et externe, est un point clef pour la qualité et la cadence de production.Dans ce mémoire, le processus industriel est détaillé depuis la fermeture du moule et l’injection du métal liquide jusqu’à l’ouverture du moule et l’extraction de la pièce (carter mécanisme RENAULT). Ensuite, le design détaillé du moule, les différentes générations de circuit de refroidissement et les paramètres de chaque étape de la fabrication utilisés compte tenu du système de refroidissement actuel sont présentés. Le circuit de refroidissement du moule est aujourd’hui positionné dans le moule de façon empirique. Le but ultime de cette thèse est de donner les éléments clés de la conception du circuit de refroidissement d’un point vue thermique. Pour cela, une modélisation complète du phénomène a été réalisée et validée par 8 thermocouples et la position du system de refroidissement a été définie a partir des équations thermiques. Le cycle thermique du moule a été donc optimisé et nous a permis d’abaisser et d’homogénéiser les champs de température à la surface du moule pendant la production en vue d’une augmentation de la productivité, la santé des pièces et la durée de vie du moule. / Reducing the weight of vehicles, specially the powertrain Group, contributes to the reduction of the emissions. Today, in order to achieve this objective, the automobile parts conception (Housing gear box, Cylinder block) in lightweight materials such as aluminum and its alloys is increasing. For the mass production, aluminum alloys are formed by a foundry process called ‘’High Pressure Die Casting’’.This process uses the metal molds. Control the thermal behavior of the mold : Heating, intern cooling (by circuit) and extern cooling, is a key point to ensure castings quality and rate of production.In this thesis, the industrial process has been detailed since the mold closing and aluminum melting injection in the die, to the mold opening time and the part (Gearbox RENAULT) ejection. Then, the mold design details, different generation of the cooling systems and the parameters of each step of the manufacturing process taking into account the actual cooling system are presented. The actual cooling systems in the dies are positioned today in empirical way. The ultimate goal of this thesis is to provide the key elements for the cooling system conception from the thermal behavior point of view. For this one, a complete modeling of the phenomena has been realized and validated by 8 thermocouples and the cooling system position has been defined from the thermal equations. The thermal cycle of the die has been optimized and allowed us to reduce and homogenize the temperature fields on the die surface during the production. The rate of production, the castings quality and the lifetime of the die have been consequently increased.

The vehicles industry is facing increasing demands for fuel efficiency and cost reduction due to environmental legislation, sustainability and customer demands. Therefore, there is a great need to develop and produce lightweight components by using materials and processes that offer higher specific strength and/or design optimization. Semi‐solid aluminium casting offers design freedom and castings with lower shrinkage and gas entrapment defects compared to high pressure die castings. The lack of understanding of microstructure and defect formation, and design data, for semi‐solid castings is a barrier for foundries and designers in the vehicles industry to use semi‐solid castings. In this study, the effect of two grain refiners on slurry formation and surface segregation of semi‐solid Al‐7Si‐0.3Mg castings produced by the Rheometal™ process was evaluated. The influence of grain refinement on primary α‐Al grain size, shape factor and solid fraction was analysed in addition to the solute content of the surface segregation layer. The influence of magnesium on the formation of intermetallic phases during solidification and the heat treatment response of Al‐7Si‐Mg semi‐solid castings was investigated. The magnesium content was varied from 0.3 to 0.6wt.% and the semi-solid castings were analysed in the T5 and T6 conditions. Energy dispersive spectroscopy was used to identify the intermetallic phases formed during solidification. Tensile testing was performed and the results were correlated to the magnesium and silicon concentration measured in the interior of the α‐Al globules formed during slurry preparation. The results suggest that the addition of grain refiner decreases the solid fraction obtained in the Rheometal™ process. However, no significant effect was observed on the α‐Al grain size and shape factor. A good correlation was obtained between the magnesium concentration in the interior of the α‐Al globules formed during slurry preparation and the offset yield strength for all alloys. The low magnesium solubility in α‐Al at temperatures in the solidification range of the Al‐7Si‐Mg alloys is suggested to be the reason for the low hardening response for the T5 heat treatment compared to the T6 condition.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-09T13:19:28Z No. of bitstreams: 1 JOSÉ JOELSON DE MELO SANTIAGO - DISSERTAÇÃO (PPGEM) 2018.pdf: 5893476 bytes, checksum: 9fec0f8b27ff639270bebb4444b2285c (MD5) / Made available in DSpace on 2018-10-09T13:19:28Z (GMT). No. of bitstreams: 1 JOSÉ JOELSON DE MELO SANTIAGO - DISSERTAÇÃO (PPGEM) 2018.pdf: 5893476 bytes, checksum: 9fec0f8b27ff639270bebb4444b2285c (MD5) Previous issue date: 2018-08-30 / Em muitas situações de projeto em sistemas mecânicos deseja-se rigidez e ao mesmo tempo uma certa flexibilidade. Nesses casos, as molas são elementos interessantes, por isso esses componentes foram bastante estudados. Em paralelo, visando ampliar as possibilidades, novos materiais têm se desenvolvido, a exemplo de materiais funcionais, como é o caso das ligas com memória de forma (LMF). As molas helicoidais fabricadas a partir de LMF são componentes promissores para aplicações como atuadores/sensores, pela capacidade de recuperar grandes deformações elásticas e pseudo-plásticas. Atualmente esses componentes são obtidos em sua maioria através da conformação de fios, a frio ou a quente, e tem aplicação consolidada no campo biomédico, porém no campo industrial as aplicações comerciais ainda são limitadas. Neste cenário, utilizar a fundição de precisão para este tipo de componente pode ampliar as possibilidades e aumentar as aplicações em diversos setores. Por outro lado, é de amplo interesse entender a relação entre as propriedades mecânicas e as configurações geométricas destes elementos. Neste contexto, o principal objetivo deste trabalho é a caracterização térmica e mecânica de molas helicoidais de LMF Ni-Ti (MLMFNiTi) com diferentes configurações, produzidas pelo processo de fundição de precisão, empregando a fusão por indução com injeção por centrifugação (FIC) em moldes cerâmicos. Os resultados obtidos mostraram que as molas produzidas apresentaram transformação de fase característica dos fenômenos de superelasticidade (SE). Por meio dos ensaios mecânicos constatou-se que as molas suportaram, no geral, deformações de até 70%. Os parâmetros dimensionais influenciaram o comportamento mecânico para o qual o aumento do passo e do diâmetro do fio fizeram aumentar a força aplicada para submeter as molas as mesmas deformações. Dessa forma, as molas produzidas apresentam características funcionais adequadas para potencializar aplicações industriais a partir de LMF Ni-Ti. / In many situations of design in mechanical systems one wants rigidity and at the same time a certain flexibility. In these cases, the springs are interesting elements, so these components were well studied. In parallel, in order to expand possibilities, new materials have been developed, such as functional materials, such as shape memory alloys (LMF). Helical springs made from LMF are promising components for applications such as actuators / sensors, for the ability to recover large elastic and pseudo-plastic deformations. Currently, these components are mostly obtained through wire forming, either cold or hot, and have consolidated application in the biomedical field, but in the industrial field commercial applications are still limited. In this scenario, using precision casting for this type of component can expand the possibilities and increase the applications in several sectors. On the other hand, it is of broad interest to understand the relation between the mechanical properties and the geometric configurations of these elements. In this context, the main objective of this work is the thermal and mechanical characterization of LMF Ni-Ti helical springs (MLMFNiTi) with different configurations, produced by the invesment casting process, using induction fusion with centrifugal injection (FIC) in ceramic molds. The obtained results showed that the produced springs presented phase transformation characteristic of the phenomena of superelasticity (SE). Through the mechanical tests it was found that the springs generally supported deformations of up to 70%. The dimensional parameters influenced the mechanical behavior for which the step increase, and the wire diameter increased the applied force to subject the springs to the same deformations. Thus, the springs produced have functional characteristics suitable to enhance industrial applications from LMF Ni-Ti.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-09T13:44:00Z No. of bitstreams: 1 ANTÔNIO ARISTÓFANES DA CRUZ GOMES - DISSERTAÇÃO (PPGEM) 2018.pdf: 3128879 bytes, checksum: 1a0aaa662fd3e47d06a1e3545ab63f87 (MD5) / Made available in DSpace on 2018-10-09T13:44:00Z (GMT). No. of bitstreams: 1 ANTÔNIO ARISTÓFANES DA CRUZ GOMES - DISSERTAÇÃO (PPGEM) 2018.pdf: 3128879 bytes, checksum: 1a0aaa662fd3e47d06a1e3545ab63f87 (MD5) Previous issue date: 2018-08-07 / CNPq / Os procedimentos cirúrgicos de reconstrução crânio facial vêm se desenvolvendo significativamente e grande parte desse progresso se deve às inovações nas técnicas cirúrgicas e ao emprego de novos materiais na fabricação dos dispositivos de fixação. O objetivo principal é tornar os procedimentos mais eficientes e menos invasivos aos pacientes, consequentemente haverá diminuição nos índices de retrabalhos. O emprego de Ligas com Memória de Forma (LMF) pode ser uma alternativa interessante nesses casos, uma vez que esses materiais possuem um comportamento adaptativo, com a capacidade de reagir a estímulos externos de natureza térmica ou mecânica. As LMF da família Ni-Ti lideram o interesse das pesquisas devido ao maior número de aplicações comerciais, principalmente nas áreas médica e odontológica. Essas LMF Ni-Ti, além de serem biocompatíveis possuem também módulo de elasticidade inferior ao de ligas de titânio, como o Ti-Al-V, e dos aços inoxidáveis. Neste contexto, o objetivo deste trabalho é desenvolver um protótipo de placa de fixação óssea, que poderá ser destinada a procedimentos de trauma e reconstrução mandibular, utilizando uma LMF Ni-Ti com características superelásticas. Foi escolhido um elemento de fixação, tipo placa, como modelo para os protótipos e as dimensões foram baseadas em componentes fornecidos comercialmente. Para a fabricação dos dispositivos optou-se pelos processos de fundição de precisão: Plasma Skull Push-Pull (PSPP), e fusão por indução com injeção por centrifugação (FIC), os quais se mostraram bastante eficazes. Foram realizados ensaios de caracterização para determinar as propriedades térmicas e mecânicas do dispositivo fabricado. Os principais resultados foram um componente de rigidez variável com a temperatura, módulo de elasticidade da ordem de 50 GPa na temperatura corpórea e vida em fadiga ente 103 e 106 para amplitudes de deslocamento em flexão entre 0,5 mm e 2,5 mm. Estes resultados de caracterização termomecânica indicam o potencial das LMF Ni-Ti e dos processos de fundição de precisão para a produção de placas de fixação óssea. / Surgical procedures for facial skull reconstruction have been developing significantly and much of this progress is due to innovations in surgical techniques and the use of new materials in the manufacture of fastening devices. The main objective is to make the procedures more efficient and less invasive to the patients, consequently there will be a decrease in the rates of reworking. The use of Shape Memory Alloys (SMA) may be an interesting alternative in these cases, since these materials have an adaptive behavior, with the ability to react to external stimuli of a thermal or mechanical nature. The SMA of the Ni-Ti family lead the research interest due to the greater number of commercial applications, mainly in the medical and dental areas. In addition to being biocompatible, these Ni-Ti SMAs also have lower modulus of elasticity than titanium alloys, such as Ti-Al-V, and stainless steels. In this context, the objective of this work is to develop a prototype bone fixation plate, which can be used for trauma and mandibular reconstruction procedures, using a Ni-Ti SMA with superelastic characteristics. A plate-type fastening element was chosen as the prototype model and the dimensions were based on commercially supplied components. In order to manufacture the devices, it was chosen the precision casting processes: Plasma Skull Push-Pull (PSPP) and induction fusion with centrifugal injection (FCI), which proved to be quite effective. Characterization tests were performed to determine the thermal and mechanical properties of the fabricated device. The main results were a variable stiffness component with temperature, modulus of elasticity of the order of 50 GPa at body temperature and fatigue life between 103 and 106 for flexural displacement amplitudes between 0.5 mm and 2.5 mm. These thermomechanical characterization results indicate the potential of Ni-Ti SMA and precision casting processes for the production of bone fixation plates.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the current competitive market, a great part of companies has as the main goal the search for continuous improvement of their products and services. Therefore, the application of statistical methods has great relevance in the quality evaluation, helping in the understanding and monitoring of the processes. In such context, the present study concerns to the use of multivariate control charts in the evaluation of the productive processes in the presence of cross-correlation, which the objective is to verify the continuous casting process stability in the production of still billets by means of Hotelling's T2 multivariate control charts applied in the estimated residual mathematical linear models. Initially, the existence of data autocorrelation was verified, it is necessary the ARIMA modeling, because when it happens, it is necessary to determine the residues and apply multivariate control charts to the residues and not on the original variables. The existence of correlation showed to be meaningful among the variables, being one of the assumptions for the statistical application T2. When the T2 chart instability is verified, it was necessary to identify the variable or the set of variables of steel temperatures in the distributor and in the distributor weight, which are responsible for the instability. Later, the estimated residues were decomposed into principal components, and with the help of the correlation of the original variables and the principal components, the variables which most contributed to the formation of each component were identified. Therefore, it was possible to detect the variables which caused the system instability, once for the steel temperature in the distributor were the T4 and T5, followed by T6, T3, T7 and T2 and for the weight of the distributor, PD4, PD5, PD3, PD6 and PD2, respectively. This way, the estimated residues from the mathematical models, the use of multivariate chart control Hotelling's T2 and the decomposition into principal components which were able to represent the productive process. This methodology allowed the understanding of the behavior of the variables and helped the monitoring of this process, as well as, in the determination of the possible variables which caused the instability in the continuous casting process. / No atual mercado competitivo, grande parte das empresas tem como principal objetivo a busca da melhoria contínua dos seus produtos e serviços. Assim, a aplicação de métodos estatísticos apresenta grande relevância na avaliação da qualidade, auxiliando na compreensão e monitoramento de processos. Nesse contexto, o presente estudo aborda a utilização de gráficos de controle multivariados na avaliação do processo produtivo na presença de correlação cruzada, cujo objetivo é verificar a estabilidade do processo de lingotamento contínuo na fabricação de tarugos de aço por meio do gráfico de controle multivariado T2 de Hotelling aplicado nos resíduos estimados de modelos matemáticos lineares. Inicialmente, foi verificada a existência de autocorrelação nos dados, sendo necessária a utilização da modelagem ARIMA, pois quando isso ocorre, deve-se proceder à determinação dos resíduos e aplicar os gráficos de controle multivariados aos resíduos e não nas variáveis originais. A existência de correlação cruzada mostrou-se significativa entre as variáveis, sendo um dos pressupostos para a aplicação da estatística T2. Verificada a instabilidade no gráfico T2, buscaram-se identificar a variável ou conjunto de variáveis das temperaturas do aço no distribuidor e peso do distribuidor, responsáveis pela instabilidade. Posteriormente, os resíduos estimados foram decompostos em componentes principais, e com o auxílio da correlação entre as variáveis originais e as componentes principais, identificou-se as variáveis que mais contribuíram para a formação de cada componente. Assim, foi possível detectar as variáveis causadoras da instabilidade do sistema, sendo que para às temperaturas do aço no distribuidor foram às temperaturas T4 e T5, seguidas de T6, T3, T7 e T2 e para o peso do distribuidor, PD4, PD5, PD3, PD6 e PD2, respectivamente. Deste modo, os resíduos estimados oriundos dos modelos matemáticos, a aplicação dos gráficos de controle multivariados T2 de Hotelling e a decomposição em componentes principais foram capazes de representar o processo produtivo. Esta metodologia possibilitou a compreensão do comportamento das variáveis e auxiliou no monitoramento do processo, bem como, na determinação das possíveis variáveis causadoras da instabilidade no processo de lingotamento contínuo.

Made available in DSpace on 2014-10-09T12:35:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:39Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP