Orientador: Maria Helena Robert / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-11-08T18:37:47Z (GMT). No. of bitstreams: 1 Delbin_Daniel_M.pdf: 8551361 bytes, checksum: 770e9d00eeb959cc6e40cf3f314faa4e (MD5) Previous issue date: 2006 / Resumo: Neste trabalho é estudada a viabilidade de produção de esponjas metálicas pela conformação de pasta tixotrópica da liga A2011, sobre camada de agente bloqueador (NaCl) posteriormente removido para formação da porosidade. Investiga-se a influência da temperatura de tratamento térmico, para obtenção da pasta semi-sólida, e da granulometria do agente bloqueador, na estrutura formada do material celular (aspecto geral, caracterização qualitativa e quantitativa dos poros, microestrutura da parede celular e densidade) e nas características de processo (forças de tixoforjamento e capacidade de penetração da pasta). São produzidos cilindros de material poroso metálico tipo sanduíche, compostos de camada porosa entre camadas maciças da liga, com três diferentes classes de porosidade: fina, média e grosseira. As esponjas foram submetidas à tomografia computadorizada e à análise metalográfica para sua caracterização estrutural. Os resultados obtidos mostram a viabilidade de obtenção de esponjas metálicas utilizando a tecnologia de semi-sólidos e o tipo de bloqueador utilizado. O sucesso do processo depende da fração líquida presente na pasta metálica tixotrópica, reduzida fração líquida pode resultar em incompleta infiltração e compressão das partículas do agente bloqueador. Nas condições analisadas a granulometria do agente bloqueador não teve influência sensível na qualidade do produto. A densidade do material poroso aumenta com o aumento da temperatura de processo, devido ao aumento da espessura de paredes metálicas na estrutura porosa / Abstract: The work analyses the possibility of the production of cellular material by pressing the A2011 alloy in the thixotropic semi-solid state, into a space holder pre-form. Space holder particles used are NaCl, which are removed from the product after the forming operation, resulting the porous material. It is investigated the influence of the thixoforming temperature and the size of space holder particles, in the structure of the obtained porous material (general aspect, quantitative and qualitative characterization of porosity, microstructure of cell walls and density of the product), as well as in the processing characteristics (required forces for infiltration, penetration ability of the slurry in the salt pre-form). Cylindrical samples, sandwich type, with a porous layer inserted between layers of compact alloy are produced, presenting three different ranges of porosity. The cellular material obtained contains opened porosity, being characterized as sponge. Products were analyzed by tomography and metallographic techniques. Results show that the proposed process is able to produce acceptable porous material, with a simple and low cost technique. The quality of the product depends rather on the processing temperature than on the size of space holder particles. Low liquid fraction in the thixotropic slurry can lead to incomplete infiltration and deformation of the pre-form. In the analyzed conditions, influence of the size of space holder particles could be observed neither in the processing ability nor in the quality of the product. Density of produced porous material increases as processing temperature increases, due to the increase of thickness of cell walls / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Dans le secteur du génie civil, le renforcement structural et la réparation des ouvrages en béton par collage de polymère renforcé de fibres de carbone (PRFC) sont des techniques désormais répandues. Les performances et la durabilité du système de renforcement sont intrinsèquement liées à la qualité du collage entre le matériau composite et le béton. Or, en pratique, les conditions environnementales et les contraintes liées au chantier ne permettent pas d’assurer l’intégrité de ce collage, dont les propriétés évoluent par ailleurs dans le temps en raison des phénomènes de vieillissement. La vérification in-situ par une méthode non-destructive de l’état du collage est donc une étape importante pour garantir les propriétés d'usage tout au long de la vie du renforcement.Une méthode d’évaluation non-destructive est développée dans le cadre de cette étude. Elle s’inspire de l’essai standard d’arrachement en traction directe bien connu sur le terrain. La méthode repose sur un essai mécanique qui caractérise le comportement en charge – déplacement de l’assemblage, et permet d’exprimer un critère d’évaluation appelé raideur d’assemblage qui dépend notamment du module d’Young de l’adhésif utilisé.La faisabilité en laboratoire de cette méthode est vérifiée sur un dispositif d’essai entièrement conçu pour les fins de l’étude. Un travail d’analyse et de dimensionnement basé sur une modélisation numérique par éléments finis permet de sélectionner des capteurs et une chaîne d’acquisition adaptés. Une formulation analytique partielle de la raideur d’assemblage est énoncée.Une campagne expérimentale sur des éprouvettes de béton renforcées par lamelles de PRFC avec trois adhésifs époxy différents est ensuite mise en œuvre. Les résultats sont interprétés en suivant une approche statistique qui prend en compte les variations de tous les paramètres d’influence. Les performances de détection de l’essai dans le cadre de notre application en laboratoire peuvent ainsi être exprimées.Des éléments contribuant à l’élaboration d’une méthodologie d’essai applicable in-situ sont enfin apportés, et les performances de l’essai sont rediscutées en vue de cette transposition sur le terrain / Over the last 30 years, repairing and strengthening techniques of concrete structures using externally bonded carbon fiber reinforced polymer (CFRP) composites have gained much popularity and are now widespread. The effectiveness of the strengthening systems highly depends on the level of adhesion between the composite material and the concrete surface. Therefore, on-site evaluation of the bond quality is crucial to assess the performance and predict the durability of the reinforcement system.It is proposed to determine the bond properties of the adhesive layer within the reinforcement system by using a nondestructive test (NDT) method derived from the standard and well-known pull-off test. This method consists in analyzing the linear load vs displacement behavior of the adhesive joint, in order to determine an assembly stiffness which can be related to the Young’s modulus of the adhesive layer.In order to investigate the feasibility of the test method, a laboratory implementation is carried out on a mechanical device fully designed for the purpose of the present study. Suitable displacement sensors and an appropriate measurement chain are chosen based on a finite element modeling and a mechanical analysis of the test. A partial analytical form of the assembly stiffness is also expressed.The test method is then applied to concrete slabs reinforced with CFRP plates using three different epoxy adhesives. A statistical assessment of all identified parameters of influence sheds light on the results. In the end, the performances of the test performed in laboratory conditions are discussed.Finally, foundations for a relevant test methodology on real field conditions are laid, and the above-mentioned performances are reviewed

nÃo hà / Nas Ãltimas dÃcadas, existiu uma crescente demanda por aproveitamento do potencial eÃlico mundial. Essa tendÃncia està transformando as pÃs eÃlicas em uma das mais importantes aplicaÃÃes dos materiais compÃsitos polimÃricos. Alguns componentes de uma turbina eÃlica sÃo confeccionados em materiais compÃsitos polimÃricos e suas pÃs eÃlicas representam o maior uso desse material. Este trabalho tem como objetivo a avaliaÃÃo dos efeitos do envelhecimento acelerado em amostras de materiais compÃsitos revestidos com poliuretano utilizados em aerogeradores. O compÃsito à constituÃdo de resina epÃxi, reforÃado com fibras de vidro e revestido com poliuretano. O envelhecimento acelerado simula de forma intensificada os intemperismos naturais (radiaÃÃo solar, umidade e temperatura). As placas compÃsitas foram caracterizadas por ensaios nÃo-destrutivos de ultrassom e emissÃo acÃstica; ensaios mecÃnicos de traÃÃo e Izod; anÃlises tÃrmicas de termogravimetria (TGA) e calorimetria diferencial de varredura (DSC); microscopia Ãptica e grau de empoamento.Devido ao alto coeficiente de atenuaÃÃo caracterÃstico de materiais com mais de um constituinte e a consequenteausÃncia de sinal acÃstico de retorno, o ensaio por ultrassomnÃo logrou Ãxito. Mediante os avanÃos da degradaÃÃo acelerada, houve estabilidade nos valores mÃdios da velocidade de propagaÃÃo da onda e do coeficiente de atenuaÃÃo nos compÃsitos, por meio do ensaio de emissÃo acÃstica. Os ensaios mecÃnicos de traÃÃo e Izod mostraram que o envelhecimento acelerado interferiunas seguintes propriedades: mÃdulo de elasticidade, tensÃo de ruptura, alongamento mÃximo e resistÃncia ao impactoIzod. Pela tÃcnica de TGA, houve alteraÃÃo na temperatura mÃxima de degradaÃÃo e estabilizaÃÃo na massa residual com os avanÃos da degradaÃÃo acelerada. Por DSC, foi possÃvel detectar diminuiÃÃo na temperatura de transiÃÃo vÃtrea (Tg). A microscopia Ãptica revelou que nÃo houve alteraÃÃes na superfÃcie do revestimento de poliuretano e na interface poliuretano-epÃxi e ocorreu degradaÃÃo na interface fibra-matriz (face exposta à radiaÃÃo) nos compÃsitos mediante os progressos de envelhecimento acelerado. Entretanto, a mediÃÃo do grau de empoamento apresentou deteriorizaÃÃosuperficial do revestimento de poliuretano. Diante de todos os resultados encontrados, conclui-se que o envelhecimento acelerado influenciou no desempenho dos materiais utilizados em aerogeradores. / In recent decades, there has been a growing demand for utilization of wind power worldwide. This trend is transforming wind blades in one of the most important applications of polymeric composites. Some components of a wind turbine are made of polymeric composites and wind blades represent the largest use of this material. This study aims to assess the effects of accelerated aging in samples of composite materials coated with polyurethane used in wind turbines. The composite is made of epoxy resin reinforced with glass fibers and coated with polyurethane. The accelerated aging test simulates an enhanced form natural weathering (solar radiation, humidity and temperature). The composite plates were characterized by non-destructive testing of ultrasonic waves and acoustic emission; tensile tests and Izod; thermal analyzes thermogravimetricanalysis (TGA) and differential scanning calorimetry (DSC); optical microscopy and the degree of chalking. Because of the high attenuation coefficient characteristic of materials with more than one constituency and the consequent absence of acoustic feedback, the ultrasound test didn`t succeed. Through the advances in accelerated degradation was stable on mean average velocity of wave propagation and attenuation coefficient of the composite by means of acoustic emission test. The tensile tests and Izod showed that the accelerated aging interfered with the following properties: modulus of elasticity, tensile strength,ultimate elongation and Izod impact. By the technique of TGA, there was change in maximum temperature of degradation and stabilization in the residual mass with the advances in accelerated degradation. By DSC it was possible to detect a decrease in glass transition temperature (Tg). The optical microscope demonstrated that no changes in the surface of the coating polyurethane and polyurethane-epoxy interface and degradation occurred in the fiber-matrix interface (the exposed radiation face) in the composite by the progress of accelerated aging. However, measuring the degree of deterioration showed chalking surface of the polyurethane coating. With all the results, these studies conclude that the accelerated aging affect the performance of materials used in wind turbines.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Materiais compÃsitos vem sendo amplamente estudados devido aos seus inÃmeros benefÃcios em relaÃÃo aos materiais metÃlicos, principalmente a elevada razÃo resistÃncia/peso, bom iso-lamento tÃrmico e boa resistÃncia à fadiga. CompÃsitos laminados, foco do presente trabalho, sÃo produzidos pelo empilhamento de um conjunto delÃminas, cada uma composta de fibras unidirecionais ou bidirecionais imersas em uma matriz polimÃrica. As estruturas de materiais compÃsitos apresentam comportamento nÃo linear, tanto fÃsico quanto geomÃtrico. Devido à elevada resistÃncia, estruturas de material compÃsito tendem a ser bastante esbeltas, podendo apresentar grandes deslocamentos e problemas de estabilidade. Adicionalmente, a consideraÃÃo da nÃo linearidade fÃsica tambÃm à importante para a simulaÃÃo de falha de estruturas laminadas. Um dos modos de falha mais importantes destas estruturas à a delaminaÃÃo, que consiste no descolamento de duas lÃminas adjacentes. No projeto de estruturas laminadas, o MÃtodo dos Elementos Finitos à a ferramenta de anÃlise mais utilizada devido a sua robustez, precisÃo e relativa simplicidade. Afim de permitir a anÃlise nÃo linear de estruturas laminadas submetidas a grandes deslocamentos, foi desenvolvida neste trabalho uma formulaÃÃo de elementos finitos sÃlidos laminados baseados na abordagem Lagrangiana Total. A simulaÃÃo do inÃcio e propagaÃÃo da delaminaÃÃo foi realizada neste trabalho utilizando Modelos de Zona Coesiva. Para este fim, foi desenvolvida uma formulaÃÃo de elementos isoparamÃtricos de interface com espessura nula e utilizados diferentes modelos constitutivos para representar a relaÃÃo entre as tensÃes e os deslocamentos relativos das faces da trinca coesiva, incluindo tanto o caso de modo I puro quanto de modo misto. As formulaÃÃes desenvolvidas neste trabalho foram implementadas no software de cÃdigo aberto FAST utilizando afilosofiade ProgramaÃÃo Orientada a Objetos. Estas implementaÃÃes sÃo apresentadas utilizando as convenÃÃes da UML. VÃrios exemplos foram utilizados para verificar e validar as implementaÃÃes realizadas. Excelentes resultados foram obtidos utilizando elementos sÃlidos laminados na anÃlise de estruturas de casca, mesmo empregando malhas com apenas um elemento sÃlido na espessura. No que diz respeito à delaminaÃÃo, verificou-se que o uso de Modelos de Zona Coesiva requer muito cuidado na escolha dos parÃmetros utilizados na anÃlise, principalmente no que diz respeito à relaÃÃo tensÃo-deslocamento relativo, tamanho dos elementos e mÃtodo de integraÃÃo numÃrica. Contudo, utilizando-se a integraÃÃo de Newton-Cotes e elementos de interface de tamanho adequado, obteve-se uma concordÃncia muito boa com resultados teÃricos e experimentais disponÃveis na literatura. De forma geral,verificou-se que o modelo coesivo exponencial apresenta maior robustez e eficiÃncia computacional que o modelo bilinear. / Composite materials has been widely studied thought the years because of it benefits compared to metals (elevated resistance/weight ratio, good thermal isolation and good fatigue resistance). Laminate composites are the focus of this work. Produced by stacked layers of fibers embed- ded on polymeric matrices, structures of composite materials presents material and geometrical non-linear behavior. Because of it elevated resistance, composite materials allow designers to create very slender structures which might present large displacements and stability problems. Additionally, considering material non-linearity is also important for collapse simulation of la- minated structures. One of the most important failure modes on laminated structures is delami- nation. Delamination is the detachment of adjacent layers. On laminated structures simulation, the Finite Element Method is one of the most used analysis tool. It is a robust, precise and relative simple operating tool. Intending analyzing non-linear behavior of laminated structures subjected to large displacements, was developed on this work a laminated solid finite element formulation based on Full Lagrangian formulation. Simulation of delamination beginning and propagation was developed on this work using Cohesive Zone models. To achieve this goal, an isoparametric formulation of interface finite elements without thickness and many constitutive models to represent the relation tension à displacement jump (relative displacement between crack faces) were developed. These models consider pure mode I and mixed mode. The formu- lations developed on this work were implemented on the open source finite element code FAST using Oriented Object Programing philosophy. These implementations are presented on UML conventions. Many examples were tested for verifying and validating all the implementations. Excellent results were obtained using laminated solid elements on the analysis of a shell struc- ture, even using meshes with only one element though thickness. On the delamination analysis, was verified that Cohesive Zone Models are very sensible related to the parameters used on the analysis, mainly tension à displacement jump model, size of elements and numerical integra- tion. Spite of it, using Newton-Cotes integration and interface elements of appropriate size, good agreements were obtained compared with theoretical results obtained on literature. In general, was observed that cohesive exponential model presents greater robustness and compu- tational efficiency than bilinear model.

O início do uso de tubete na década de 80 revolucionou os viveiros, e hoje mesmo apresentando desvantagens, é amplamente difundido em todo o setor florestal. Esses tubetes de polipropileno, derivado do petróleo, possuem dois problemas: uso de fonte não renovável e resíduos para descarte. Uma alternativa é a substituição por plásticos biodegradáveis. Os objetivos foram avaliar: (a) a taxa de decomposição do compósito; (b) o crescimento em altura e em diâmetro do colo (DAC); (c) a produção de biomassa aérea e radicular; (d) a concentração de nutrientes nos tecidos vegetais; (e) a eficiência do uso de condições ambientais e de atributos do solo para predizer a taxa de decomposição. Os estudos no processo seminal ocorreram no viveiro da ESALQ, em Piracicaba. Para estudar a taxa de decomposição do compósito, utilizaram-se formulações com 20 e 30% (p p-1) de pó de madeira. No verão e no inverno aplicaramse 150; 225 e 300 g de N m-3 de substrato na fertilização de base. A diminuição de massa foi mensurada a cada dez dias, até 90 dias. Avaliou-se se o crescimento em altura e em DAC de mudas seminais entre 40-90 dias após a semeadura, a produção de biomassa e concentração de macronutrientes aos 90. No plantio realizado na E.E.C.F. de Anhembi, em três blocos ao acaso avaliou-se o crescimento em altura, em DAC e de produção biomassa, aos 15, 30, 45, 60, 90 e 120 dias. Para as mudas clonais utilizou-se tubete e minitubete de polipropileno, tubetes na coloração normal e na coloração escurecida, e minitubete de compósito. O estudo realizou-se em quatro viveiros e quatro plantios de Eucalyptus sp. no estado de São Paulo. No viveiro utilizouse 4 blocos casualizados. O crescimento em altura e em DAC, e a biomassa foram mensurados aos 90 dias. O plantio clonal em três blocos ao acaso foi mensurado em altura, DAC e produção de biomassa aos 15, 30, 60, 90, 120 e 150 dias. A concentração de macronutrientes foi determinada aos 150 dias. Os dados foram submetidos aos testes de normalidade, de homogeneidade de variâncias, da Análise de Variância e de Tukey. A análise da relação entre as variáveis dependentes e independentes foi realizada por meio de análises de correlação e de regressão. O aumento da dose de N e do teor de madeira não proporcionou aumento da taxa de decomposição, ao contrário da estação climática. A abertura de fissuras causou deformação do tubete, dificultando o manejo. As mudas seminais, crescimento e biomassa não diferiram no verão. Os plantios seminais não diferiram em crescimento e em biomassa. No sistema clonal crescimento e biomassa diferiram nos viveiros. No plantio clonal, crescimento e produção de biomassa não diferiram em três sítios. Tubetes e minitubete de compósito não impediram o desenvolvimento do sistema radicular. A diminuição da massa dos tubetes ou minitubete de compósito, em produção de mudas seminais ou clonal, pôde ser prevista com alta precisão em função das condições ambientais. Da mesma forma nos plantios seminais. No plantio clonal pelo menos em dois sítios houve alta relação. / The introduction of plastic tubes on 80s revolutionized nurseries, and nowadays even with disadvantages, is widespread throughout the forest sector. These polypropylene tubes, derived from petroleum, have two problems: use of a nonrenewable resource and waste for disposal. An alternative is the substitution for biodegradable plastics. The objectives were to assess: (a) the rate of decomposition of the composite, (b) the growth in height and ground level diameter (DAC), (c) the production of stem and root biomass, (d) the concentration of nutrients on plant tissues, (e) the efficiency of use of environmental conditions and soil properties to predict the rate of decomposition. Studies in the seminal case occurred in ESALQ´s nursery, Piracicaba. To study the rate of decomposition of composite were used formulations with 20 and 30% (p p-1) of wood powder. During summer and winter were applied 150, 225 and 300 g N m-3 of substrate for base fertilization. Decrease in mass was measured every ten days until 90 days. We evaluated the growth in height and DAC from seedlings between 40-90 days after sowing, the production of biomass and macronutrients at 90. On planting, held at E.E.C.F. of Anhembi in three randomized blocks, were evaluated height growth, DAC and biomass production at 15, 30, 45, 60, 90 and 120 days. For cuttings, we used minitubes and tubes of polypropylene, and tubes with normal and darkened colors, and minitubes of composite. The study took place in four nurseries and four Eucalyptus sp. plantations at state of São Paulo. At nursery we used four randomized blocks. The growth in height, DAC and biomass were measured at 90 days. The clonal plantation in three randomized blocks was measured in height, DAC and biomass production at 15, 30, 60, 90, 120 and 150 days. The concentration of macronutrients was determined at 150 days. Data were tested for normality, homogeneity of variance, analysis of variance and Tukey test. Analysis of relationship between dependent and independent variables was performed using correlation and regression. The increase of N and wood content did not increase the rate of decomposition, unlike the weather season. Opening of cracks caused deformation of the tube, making it difficult to manage. The growth and biomass of seedlings did not differ on summer. Seminal plantations did not differ in growth and biomass. At clonal system, growth and biomass differed in nurseries. In clonal plantation, growth and biomass production did not differ at three sites. Minitube and tubes of composite did not prevent the development of root system. Decrease of tube or minitube of composite masses in production from seedlings or cuttings was predicted with high accuracy, as a function of environmental conditions. Likewise in seminal plantations. In clonal planting, at least two sites, showed high relation.

Les supercondensateurs sont des dispositifs de stockage de l'énergie électrique particulièrement intéressants pour les applications de puissance. Les rendre flexibles permet de considérer de nouvelles possibilités d'intégration. Néanmoins, l'optimisation de la densité d'énergie, point faible de ces dispositifs, passe par la recherche et l'étude de nouveaux matériaux d'électrode et d'électrolytes. Dans ce but, ce travail de thèse s'est orienté vers des matériaux pseudo-capacitifs, avec l'utilisation d'électrodes à base de MnO2, et d'électrolytes à base de liquide ionique fonctionnalisé de type biredox. Afin de conserver le caractère flexible des électrodes, le dioxyde de manganèse a d'abord été synthétisé pour la formulation d'encres à pulvériser sur substrat flexible. A cette occasion, l'influence de dispersants sur les performances a été étudiée. Les performances de matériaux nanocomposites à base de fibres de carbone et de graphène décorés par MnO2 ont ensuite été évaluées. Les contributions faradiques et surfaciques à la capacité développée par MnO2 ont ensuite été déterminées par une étude électrochimique fine. Enfin, l'étude d'un nouveau liquide ionique fonctionnalisé utilisé dans un dispositif carbone/carbone a confirmé l'attractivité de ces phénomènes faradiques dans les performances électrochimiques d'un supercondensateur. / Supercapacitors are attractive electrical energy storage devices for power applications. As flexible devices new integration opportunities can be consider. Nevertheless, the optimization of the energy density, weak point of these devices, proceeds through the search and the study of new electrode materials and electrolytes. In this aim, this thesis work is turned towards so called pseudo-capacitive materials, with the use of MnO2-based electrodes, and biredox Ionic Liquid electrolytes. To preserve the flexible behavior of the electrodes, the manganese dioxide was, at first, synthesized for the formulation of an ink to be sprayed on flexible substrates. The influence of dispersing agents on the electrochemical performances was evaluated. Performances of nanocomposite materials prepared with carbon nanofibers and graphene oxide sheets were also studied. Faradaic and surface contributions to the capacity developed by MnO2 electrode material were then determined by an advanced electrochemical study. Finally, the study of a new Ionic Liquid used in a symmetrical carbon/carbon supercapacitor confirmed the attractiveness of these Faradaic phenomena for the enhancement of the supercapacitor electrochemical performances.

Le sujet du projet de thèse réalisée en cotutelle entre Laboratoire Roberval à l'Université de Technologie de Compiègne et le Centre de Composites à Haute Performance d'École Polytechnique de Montréal porté sur une proposition de l'architecture du deep learning avec sémantique pour la création automatisée des modèles de la microstructure de matériaux composites à partir d'imagerie de la micrographie aux rayons X. La thèse consiste de trois parties principales : d'abord les méthodes du prétraitement de données microtomographiques sont relevées, avec l'accent sur la segmentation de phases à partir d'images 2D. Ensuite, les propriétés géométriques des éléments de phases sont extraites et utilisées pour classifier et identifier de nouvelles morphologies. Cela est démontré pour le cas de composites chargés par les fibres courtes naturelles. L'approche de classification à l'aide des algorithmes d'apprentissage est reprise pour étudier les défauts dans un composite, mais en ajoutant les aspects spatiaux. En plus, un descripteur de haut niveau "génome de défauts" est introduit, qui permet de comparer l'état de défauts dans les différents échantillons. La deuxième partie introduit la segmentation structurelle sur l'exemple du renfort tissé du composite. La méthode repose sur un modèle du krigeage dual, calibré par l'erreur de segmentation provenant d'algorithme d'apprentissage. Finalement, le modèle krigé est repris pour construire une formulation stochastique du renfort à travers de processus gaussien et la distribution des propriétés physiques de la microstructure est extraite et prête pour la simulation numérique de la fabrication ou du comportement mécanique. / The subject of the thesis project between Laboratoire Roberval at Université de Technologie Compiègne and Center for High-Performance Composites at Ecole Polytechnique de Montréal considered the design of a deep learning architecture with semantics for automatic generation of models of composite materials microstructure based on X-ray microtomographic imagery. The thesis consists of three major parts. Firstly, the methods of microtomographic image processing are presented, with an emphasis on phase segmentation. Then, the geometric features of phase elements are extracted and used to classify and identify new morphologies. The method is presented for composites filled with short natural fibers. The classification approach is also demonstrated for the study of defects in composites, but with spatial features added to the process. A high-level descriptor "defect genome" is proposed, that permits comparison of the state o defects between specimens. The second part of the thesis introduces structural segmentation on the example of woven reinforcement in a composite. The method relies on dual kriging, calibrated by the segmentation error from learning algorithms. In the final part, a stochastic formulation of the kriging model is presented based on Gaussian Processes, and distribution of physical properties of a composite microstructure is retrieved, ready for numerical simulation of the manufacturing process or of mechanical behavior.

Pavement foundations for major roads in the UK were historically designed on an empirical basis, related to a single design chart, restricting the incorporation of superior performing materials or materials for which the empirical data sets were not available. The adoption of performance based specifications was promoted as they are perceived to 'open up' the use of alternative materials (including 'local' sources of primary materials) or techniques, and allow for the incorporation of superior performance into the overall pavement design. Parallel developments to the performance based design of pavement foundations (allowing for superior performance) and in situ testing required the support of laboratory based performance tests. These laboratory based tests were required to determine material performance parameters (elastic modulus and resistance to permanent deformation) for both unbound and hydraulically bound pavement foundation materials. A review of the available laboratory apparatus indicated that they were either; unrealistic (and hence unable to provide the required material performance parameters), or overly complex and more suited to fundamental research. Therefore, the requirement for developmental research work was identified. The research reported herein details the development, manufacture and initial evaluation of simplified laboratory apparatus (the Springbox for unbound materials and static stiffness test for hydraulically bound mixtures) designed to produce the performance parameters of elastic modulus and relative resistance to permanent deformation for pavement foundation materials. The equipment and test procedure evaluation was undertaken across a range of materials, giving initial guidance on likely in situ performance. The innovative laboratory apparatus and materials guidance (including the potential to use recycled and secondary aggregates) was incorporated into key Highways Agency specification and guidance documents, which in turn influence construction practice outside of motorways and major trunk roads. This research concludes by outlining a number of recommendations for continued development and evaluation, including feeding back data sets from long term in situ performance testing for subsequent refinement of assumptions.

A utilização de polímeros ligno-celulósicos combinados com polímeros artificiais na forma de materiais compostos é fruto do desenvolvimento de uma linha de pesquisa que tinha como objetivo inicial a utilização dos primeiros como enchimento de uma matriz termofixa ou termoplástica aglutinante. Com o advento da necessidade do reaproveitamento de resíduos de processos industriais, as pesquisas e a utilização de resíduos fibrosos e partículas de madeira cresceram em importância e passaram a contribuir ainda mais decisivamente no desenvolvimento de novas técnicas, processos, equipamentos e insumos que possibilitam ampla gama de aplicações dos produtos obtidos. O presente trabalho objetivou a fabricação de placas compostas de serragem de duas espécies amplamente utilizadas em serrarias combinada com polietileno de baixa densidade reciclável (PEBD). Serragem e farinha de madeira de Pinus elliottii e Eucalyptus grandis , provenientes de lenho e de casca, foram separadas, beneficiadas e misturadas com partículas de PEBD também classificadas por tamanho, na proporção de 40% de madeira e 60% de plástico. A mistura foi prensada a 150 ° C por 30 minutos à pressão de 3 MPa. Foram fabricadas 44 placas de 6 mm de espessura nominal e 40 x 50 cm de lados, em 4 repetições de 11 tratamentos. Foram produzidos corpos-de-prova de todas as placas para os ensaios físicomecânicos segundo a norma ASTM D-1037, determinando-se a massa específica, o teor de umidade, a variação da massa e da espessura ocorridas em 2 e 24 horas de imersão em água, o módulo de elasticidade e o módulo de ruptura na flexão estática, a resistência à compressão e a força máxima de arrancamento de prego e de parafuso de fenda. O lenho de Pinus de granulometria fina combinado com PEBD fino apresentou as melhores propriedades físicomecânicas. Os tratamentos com lenho de Eucalyptus obtiveram o melhor desempenho geral e naqueles em que se utilizou a casca de Pinus os resultados não foram satisfatórios. Dentre os tratamentos que utilizaram cascas, a de Eucalyptus de granulometria grossa foi superior. O lenho de Pinus , principalmente em granulometrias mais finas e homogêneas revelaram-se promissores na utilização externa e as placas obtidas de casca de Pinus revelaram um grande potencial de utilização em usos internos não estruturais, como material alternativo. / Using ligno-celullose polymers combined with artificial polymers in form of composite material is result of a developing research line which had as initial objective the use of the firsts as just filling material in an agglutinant thermoplastic matrix. Due to the necessity of reusing industrial processing residues, the research and utilization of fiber and woody particles had grown in importance and started to contribute on the development of new techniques, processes, equipment and materials that make possible creating a huge variety of products and applications. The present work had the objective of manufacturing composite boards using sawdust from two different species widely used in sawmill combined with recyclable low density polyethylene. Pinus elliotii and Eucalyptus grandis sawdust and wood flour, produced from lumber and bark had been separated, treated and mixed with PEBD particles also classified by size, in the proportion of 40% wood and 60% plastic. The mixture was pressed at 150 °C during 30 minutes under 3 MPa pressure. It were manufactured 44 boards 6 mm nominal thickness and 40 x 50 cm sides in 4 replications of 11 treatments. Samples were obtained from all boards for physicmechanical tests according to ASTM D – 1037 standard, determining specific gravity, moisture content, mass and thickness variation occurred in 2 and 24 hours in water, modulus of elasticity and modulus of rupture in the static bending, compression strength and the withdrawal load of nail and screw. The Pinus wood of thin granulosity combined with thin LDPE had presented better physic-mechanical properties. The treatments in which was used Eucalyptus wood had shown better general performance and those in which was utilized Pinus bark had not presented satisfactory performance. Amongst the treatments in which bark was used, the Eucalyptus of thick granulosity had showed better performance. Boards made of Pinus wood specially in thinner and homogeneous granulosities seems to be excellent for exterior application and those in which was used Pinus bark had shown great potential as an alternative material for non structural purposes for interior applications.

Tendo como vantagem a elevada resistência ao choque térmico da zircônia:magnésia e a alta condutividade iônica da zircônia:ítria, compósitos dessas cerâmicas foram preparados por meio da mistura, em diferentes concentrações, de eletrólitos sólidos de ZrO2: 8,6 mol% MgO e de ZrO2: 3 mol% Y2O3, compactação e sinterização. A caracterização microestrutural foi feita por meio de difração de raios X e microscopia eletrônica de varredura. A análise do comportamento térmico foi feita por dilatometria. As propriedades elétricas foram estudadas por meio de espectroscopia de impedância. Foi feita uma montagem experimental para monitorar a resposta elétrica gerada em função do teor de oxigênio a altas temperaturas. Os principais resultados mostram que os compósitos cerâmicos são parcialmente estabilizados nas fases monoclínica, cúbica e tetragonal, e apresentam comportamento térmico similar ao apresentado por eletrólitos sólidos de zircônia:magnésia de dispositivos sensores de oxigênio. Além disso, os resultados de análise de espectroscopia de impedância mostram que a adição da zircônia:ítria melhora o comportamento elétrico da zircônia:magnésia, e que resposta elétrica gerada é dependente do teor de oxigênio a 1000 °C, mostrando ser possível construir sensores de oxigênio utilizando compósitos cerâmicos. / Taking advantage of the high thermal shock resistance of zirconia-magnesia ceramics and the high oxide ion conductivity of zirconia-yttria ceramics, composites of these ceramics were prepared by mixing, pressing and sintering different relative concentrations of ZrO2: 8.6 mol% MgO and ZrO2: 3mol% Y2O3 solid electrolytes. Microstructural analysis of the composites was carried out by X-ray diffraction and scanning electron microscopy analyses. The thermal behavior was studied by dilatometric analysis. The electrical behavior was evaluated by the impedance spectroscopy technique. An experimental setup was designed for measurement the electrical signal generated as a function of the amount of oxygen at high temperatures. The main results show that these composites are partially stabilized (monoclinic, cubic and tetragonal) and the thermal behavior is similar to that of ZrO2: 8.6 mol% MgO materials used in disposable high temperature oxygen sensors. Moreover, the results of analysis of impedance spectroscopy show that the electrical conductivity of zirconia:magnesia is improved with zirconia-yttria addition and that the electrical signal depends on the amount of oxygen at 1000 °C, showing that the ceramic composites can be used in oxygen sensors.