OBJETIVO: o Fator-C é normalmente usado para predizer a tensão de contração em interfaces compósito-dente. Foi delineado um estudo para contribuir a esclarecer os elementos que permitem prever a tensão em interfaces de restaurações adesivas. Teoricamente, a tensão varia em função da oposição à contração (rigidez do substrato), da complacência e das dimensões e propriedades mecânicas do compósito. MÉTODOS: foram obtidos pelo Método de Elementos Finitos (MEF) 8 modelos estilizados 3D não-lineares de cavidades Classe I mantendo constantes o volume (20 mm3) e a espessura das paredes (20 mm) e com variação do Fator-C (1,9 a 13,5). Foi simulado contato tipo glue entre compósito e dente. A contração de polimerização, por analogia térmica do compósito, foi 1%. Foram analisadas as tensões e deformações principais. Foi também idealizado um método para calcular por MEF a complacência regionalizada e foi avaliada sua validade pela comparação do resultado obtido por este método com o valor de complacência calculada analiticamente para um cubo de dentina de 1 mm de lado fixado numa de suas faces. Foi ainda idealizado um método para calcular, para cada formato de cavidade, o volume útil de compósito capaz de influir para aumentar o pico de tensão na interface. Por fim, com os elementos anteriores, foi calculado para cada cavidade um valor de Fator-CA, dependente da complacência na região de pico e do volume útil de compósito. Foi avaliada a capacidade de predizer o pico de tensão mediante o teste de correlação (Pearson) entre o pico de tensão e o Fator-CA, bem como entre o pico de tensão e o Fator-C. RESULTADOS: os picos de tensões provocadas pela contração em cavidades de classe I tendem a diminuir em função do aumento do Fator-C, embora o teste de Pearson evidenciou significância apenas para a tensão Máxima Principal na parede XZ e no eixo Z. O cálculo da complacência regional obtido por MEF foi de 0,0652 m/N, bem próximo ao valor analítico (0,0666 m/N). O Fator-CA correlacionou significantemente e positivamente com as três tensões obtidas na quina (Von Mises, Máxima Principal e Máxima Cisalhante). CONCLUSÕES: o aumento do Fator-C não conduz ao aumento dos picos de tensão em cavidades de classe I. O método de cálculo de complacência é válido para estruturas complexas. O Fator-CA permite predizer os picos de tensão em compósitos aderidos em cavidades de classe I. / OBJECTIVES: The C-Factor is normally used to predict the shrinkage stress at composite-tooth interfaces. A study was outlined for clarifying the elements which allows providing the stress at bonded restorations interface. Theoretically, the stress varies as a function of the opposition to the shrinkage (substrate stiffness), the compliance, dimensions and mechanical properties of the composite. METHODS: Eight 3D non-linear stylized models of Class I cavities were obtained by the Finite Element Method (FEM), maintaining the volume (20 mm3) and wall thickness (2 mm) constant and varying the C-Factor (1.9 through 13.5). A \'glue\' contact between the composite and teeth was simulated. A 1% polymerization shrinkage was simulated by using thermal analogy of the composite. Principal stresses and strains were analyzed. A method for calculating the local compliance by FEM was also idealized as well as its validity of comparing the obtained result with the analytical compliance value of a 1 mm dentin cube, with fixation at one of its faces. A method for calculating, for each cavity shape, the \'useful volume\' of the composite, which is able to influence on the stress peak increase at the interface, was further idealized. And finally, using elements mentioned before, a compliance dependent value, so-called CA-Factor, was calculated for each cavity, at peak and \'useful volume\' of the composite regions. The capability on predicting the stress peak by the correlation test (Pearson) between the stress peak and the CA-Factor as well as between the stress peak and the C-Factor was also evaluated. RESULTS: the stress peaks generated by the shrinkage on Class I cavities tend to decrease as a function of the C-Factor, though the Pearson only showed the significance for the maximum principal stress at the XZ wall and Z axis. The local compliance calculation obtained by FEM was 0.0652 m/N, which was very close to the analytical one (0.0666 m/N). The CA-Factor presented a positive and significant correlation with all three stresses obtained at the trihedral angle formed by two occlusal edges. (Von Mises, maximum principal and maximum shear stresses). CONCLUSION: the increase of the C-Factor does not lead to the increase of the stress peaks in Class I cavities. The method for calculating the compliance is valid for complex structures. The CA-Factor allows providing the stress peaks for bonded composites on Class I cavities.

Neste trabalho avaliou-se o comportamento estrutural do sistema misto madeira-concreto para tabuleiros de pontes, com ênfase na análise dinâmica dos conectores de cisalhamento, para dois tipos de conectores: \"vertical\" e em \"X\". Foram efetuadas duas principais abordagens, numérica e experimental, além de um amplo levantamento teórico sobre o tema com base na literatura disponível. Os ensaios experimentais foram realizados em corpos-de-prova de madeira como também em corpos-de-prova mistos e vigas mistas de madeira-concreto. Todos os corpos-de-prova e vigas foram submetidos a solicitações estáticas e dinâmicas, considerando-se os diversos materiais envolvidos na ligação. A análise numérica dos sistemas mistos foi efetuada com base no método dos elementos finitos, a partir da utilização do software ANSYS. Os resultados experimentais mostraram que ambos os sistemas de conexão perderam efetivamente rigidez para um total de 1 x \'10 POT.6\' ciclos de carga aplicados, sendo a maior parcela desta perda verificada para os ciclos iniciais. Além disso, o sistema de conexão \"vertical\" apresentou maior facilidade de execução quando comparado com o sistema de conexão em \"X\". A partir dos resultados numéricos constatou-se que a perda de rigidez ocorreu devido ao acúmulo do dano localizado nos materiais, nas regiões dos conectores. Os resultados numéricos mostraram uma boa concordância com os resultados experimentais. Para finalizar, foram propostos os valores dos níveis máximos e mínimos de carga cíclica, como também da frequência de excitação a serem utilizados nos ensaios dinâmicos para a verificação da rigidez dos sistemas mistos de conexão. / In this work was evaluated the structural behavior of log-concrete composite deck bridge system, with emphasis in the dynamic analysis of the shear connectors using two types of connectors: \"vertical\" and \"X\". Two main approaches were considered, numeric and experimental, besides a wide theoretical study about the theme with base in the available literature. The experimental studies were accomplished in specimens of wood, wood-concrete specimens and wood-concrete beams. All of the specimens and beams were subjected to static and dynamic loads considering several materials in the composed connection system. The numeric analyze of the composed systems was made with base in the method of the finite elements using the software ANSYS. The experimental results showed that both connection systems reduced stiffness really for 1 x \'10 POT.6\' applied load cycles, and the largest portion of this reduction happens in the initial cycles. Besides, the system of \"vertical\" connection presented larger execution easiness when compared with the system \"X\" connection. The numeric results showed that the reduced stiffness of the connection systems happened due to the accumulation of the located damage of the materials in the areas of the connectors. The numeric and experimental results comparison showed a good agreement. It was proposed values for the maximum and minimum levels of cyclical load, as well as for the frequency to be used in the dynamic tests for the verification of the reduced stiffness of the composite system of connection.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Juntas coladas têm se mostrado como a principal alternativa de união entre componentes fabricados em materiais distintos ou não, tendo como vantagem principal a ausência de aporte de calor e melhor distribuição de tensões. A literatura mostra que estudos anteriores foram realizados com o objetivo de caracterizar diversas propriedades associados às juntas, porém, pouco ainda se conhece sobre o comportamento dessas uniões relacionado à fluência. Os ensaios de fluência têm como principal desvantagem a baixa produtividade de resultados visto que, na maioria dos casos, os equipamentos aptos a realizarem este tipo de teste ensaiam apenas um corpo de prova por vez. Neste caso, o tratamento estatístico é baseado em uma pequena quantidade de resultados, reduzindo a confiabilidade na predição do comportamento em fluência. O Laboratório de Adesão e Aderência (LAA/UERJ/IPRJ) desenvolveu o equipamento pneumático de fluência (EPF) capaz de realizar dez ensaios simultâneos com parâmetros distintos. Este trabalho investiga o comportamento de juntas de cisalhamento simples (SLJ) compostas por substratos metálicos colados com adesivo epóxi e poliuretano. As juntas foram fabricadas em conformidade a norma ASTM D 1002, seguindo procedimento de preparo RT-003/08 TMC/CENPES/PETROBRAS. Os resultados mostram que, para projetos onde esteja prevista utilização das juntas durante longos períodos de tempo sob carregamento, conhecer apenas suas tensões médias de ruptura não é o suficiente para garantir a segurança do empreendimento. É proposto um modelo inicial do comportamento sob fluência de juntas coladas. / Bonded joints have been used as the main alternative to join components made of different materials, especially because high temperatures, like in welding process, are not required and because tensions are better distributed. Literature shows that although prior studies focused on the evolution of several mechanical properties related to joints, little is known about the creep behavior of bonded joints. Creep testings main disadvantage is the low productivity of results, since that, in most cases, testing machines capable of performing these tests only test one joint at a time. In this case, statistical treatment is made based on a small amount of results, reducing the reliability of the predictions. Thus, the Laboratory of Adhesion and Adherence (LAA/UERJ/IPRJ) developed a pneumatic creep equipment (PCE), capable of testing ten specimens simultaneously, under distinct scenario. This work looks into the behavior of single-lap joints (SLJ) made of metallic substrate and bonded with epoxy and polyurethane adhesives. The joints were produced according to ASTM D 1002 standard, following the RT-003/08 TMC/CENPES/PETROBRAS repair procedure. Results show that, for long term applications, knowing the average tensile strength of the joints isnt enough to guarantee project safety. An initial model for the creep behavior of bonded joints is proposed.

O presente trabalho consiste basicamente no desenvolvimento de um programa de engenharia denominado SAJ (sistema de análise de juntas) capaz de realizar uma análise detalhada do comportamento de dois dos diversos tipos de juntas coladas existentes, a junta simples colada (\"single lap joint\") e a junta dupla colada (\"double lap joint\"). Sendo que foram analisadas juntas coladas com aderentes de material compósito ou, então, compostas de aderentes de compósitos e metal. O programa de engenharia desenvolvido possibilita o cálculo das tensões, dos esforços e dos deslocamentos nessas juntas. Para validar o referido programa, os resultados obtidos do mesmo foram confrontados com os resultados obtidos para condições semelhantes utilizando \"softwares\" comerciais de elementos finitos e de cálculo de juntas. Após a validação do programa, são apresentados alguns estudos de fatores que influenciam na resistência da junta colada, verificando a influência do comprimento de \"overlap\" (sobreposição), a rigidez do adesivo e a espessura da camada adesiva. Também é apresentada uma análise de falha dos aderentes de compósito evidenciando assim, as potencialidades e limitações desta ferramenta computacional para a área de desenvolvimento de produto. / This work consists on the development of software called SAJ which can analyze a bonded joint behavior in detail, not only for single lap joint, but also, for double lap joint. These joints could be made of composite/composite materials or metal/composite as adherentes. The software developed can calculate the joints stresses, loads and displacements. The results obtained are compared to the results obtained using commercial software and the same problems proposed. After the validation of SAJ, some studies were performed in order to determine how some characteristics affect the joint stresses distribution as overlap length, adhesive elastic modulus, adhesive thickness and a failure analysis of composite adherents showing the potential and limitation of this computational tool for the product development area.

Devido a suas vantagens comparadas aos métodos tradicionais de união mecânica, a utilização de juntas coladas estruturais só tende a crescer, entretanto, devido suas propriedades e modos de falha dependerem de diversos parâmetros (tratamento superficial, geometria, material, condições de tralho, etc.) uma utilização mais ampla desta técnica ainda é restrita pela ausência de modelos de falhas confiáveis. O presente trabalho consiste na apresentação de métodos para fabricação de juntas coladas em material compósito e verificação da influência da espessura da camada adesiva na resistência de juntas simples coladas (single lap joints) submetidas à tração. São também apresentados métodos para fabricação dos aderentes, corpos de prova de adesivo puro para ensaios de caracterização e realização de ensaios mecânicos para obtenção das propriedades mecânicas tanto dos aderentes quanto do adesivo. As propriedades mecânicas dos aderentes e do adesivo foram obtidas através de ensaios realizados em uma máquina de tração universal com o auxílio da técnica de correlação digital de imagem, e a obtenção das energias críticas de resistência à fratura (GIc,GIIc) da camada adesiva foram calculadas através de ensaios Double Cantilever Beam (DCB) e End Notched Flexure (ENF). Foram estudados métodos para gerar falha coesiva nas juntas adesivas, sendo que o melhor método encontrado foi o de tratamento superficial dos aderentes com jateamento abrasivo seguido pela limpeza superficial com acetona. O controle preciso da espessura da camada adesiva foi alcançado através do desenvolvimento de um dispositivo de fácil construção, compostos por suportes de madeira, hastes e linhas de nylon. Nos ensaios em juntas coladas foi constatado uma relação inversamente proporcional entre a espessura da camada adesiva e a resistência máxima suportada pela junta, ou seja, quanto maior a espessura do adesivo menor sua resistência. Os métodos aqui apresentados foram os resultados de vários meses de estudo e compreensão das normas e técnicas disponíveis na literatura, o aprimoramento das técnicas foram frutos de um ciclo compostos por fabricação, testes e análise de resultados. / Amongst the joining techniques, adhesively bonding joints are one of the most commonly applied nowadays. However, a lack of reliable failure criteria still exists, limiting in this way a more widespread application of adhesively bonded joints in principal load-bearing structural applications. An accurate strength prediction of the adhesively bonded joints is essential to decrease the amount of expensive testing at the design stage. This work consists to show methods for manufacturing single lap joints and to verify the adhesive thickness influence on the joint resistance. The manufacturing process of the composite adherends and adhesives for bulk tests was also covered. The mechanical properties of the adherends and bulk adhesive were performed on a universal testing machine with assistance of a digital image correlation (DIC) technique. The fracture toughness energy release rates (GIc,GIIc) of the adhesive layer were obtained respectively through Double Cantilever Beam (DCB) and End Notched Flexure (ENF) tests. Cohesive failure was achieved by grit blasting the adherents followed by cleaning with acetone. A constant adhesive thickness was guaranteed by placing nylon fishing lines between the adherents. Single lap joints tests showed that the joint resistance decrease with increasing adhesive thickness.

Les lanceurs spatiaux sont des structures complexes associant une multitude de composants. L’assemblage de ces éléments doit répondre à un niveau de performance élevé. Le collage structural demeure un bon candidat en raison des nombreux avantages qu’il présente. Cependant, cette technologie montre des inconvénients. En raison des changements brusques de géométrie et de propriétés matériaux, des concentrations de contraintes apparaissent aux extrémités du joint de colle. Ce phénomène appelé effets de bords est néfaste pour la tenue mécanique de l’assemblage collé. La présence des effets de bords exclut l’utilisation de critères en contrainte utilisés classiquement. Le dimensionnement d’assemblages collés requiert des outils fiables prenant en compte ces effets de bords. Dans cette étude, un modèle de ruine incrémentale, associant une approche en contrainte et en énergie, est utilisé. L’utilisation de cet outil dans un cadre industriel, impose de répondre aux besoins d’un Bureau d’Études, notamment en termes de coût de calculs. Afin de le diminuer, une implémentation semi-analytique, est tout d’abord développée. Puis, une seconde méthode d’implémentation, basée sur la méthode des Eléments Finis, permet une prévision plus précise de la ruine d’un assemblage. La pertinence de ces deux approches a été vérifiée pour plusieurs configurations de joints collés. Des campagnes d’essais, destinées à confronter les résultats expérimentaux aux prévisions numériques, ont été réalisées. Dans le cadre de ce travail, un montage de collage et d’essai pour assemblages tubulaires a en particulier été développé. L’objectif du pré-dimensionnement est d’identifier une zone d’intérêt dans l’ensemble du domaine d’étude. Aussi, une étude paramétrique peut être requise afin de réaliser cette tâche. Afin de réduire le coût de calcul, une méthode d’interpolation spatiale appelée Krigeage a été mise en œuvre, et permet la construction efficace d’une surface de réponse. / Space Launchers are complex structures composed of a large number of elements. The assembling of these components must show a high level of reliability. The use of adhesive bonding technology is an interesting solution since it presentsseveral assets compared to “classical” joint techniques (such as riveting, bolting and welding), mainly because it can help to construct lighter and less energy consuming systems However„ the implementation of adhesives also has somedrawbacks. Due to the strong variations of geometrical and material properties, stress concentrations appear at the extremities of the joint. This phenomenon; called edge effects; has a great influence on the failure of the bond. As a result, the simple use of a classical stress or energetic criteria is not appropriate to predict the fracture of such structures. Therefore, it is obvious that the design of bonded assemblies requires reliable tools to take the edge effects into account. In this work an incremental failure model, which combines the stress and energetic criteria, is used. In order to decrease the computational cost, a semi-analytical application of this model is proposed. This is intended to make the approach more interesting to be implemented in an industrial environment. The accuracy of the prediction of the failure load is enhanced by means of the Finite Element method. The reliability of both the semi-analytical and Finite Element approaches is verified by comparing the model predictions with experimental data issued from double-notched Arcan and tubular specimen geometries. The aim of the pre-design phase is to identify the critical area in the whole range of the application of the studied geometry. Therefore, the realization of a parametric study is required in order to build a response surface. In the present study, this has been achieved by means of spatial interpolation using the Kriging model.

Afin d’optimiser le procédé de production de culasses automobiles en aluminium et d’améliorer sa fiabilité, une meilleure connaissance du comportement des noyaux de fonderie est nécessaire. Les noyaux sont des matériaux composés de grains de sable liés par une résine en faible proportion, et servent à mouler les conduits et cavités intérieurs des pièces métalliques. Au cours de leur cycle de vie, les noyaux sont amenés à subir de fortes températures et des sollicitations mécaniques complexes. L’objectif de cette étude est de caractériser le comportement thermomécanique des noyaux sous diverses sollicitations selon le taux de liant, la température et surtout l’état de dégradation de ce liant. En particulier, les travaux de cette thèse s’attardent sur les mécanismes d’endommagement et de fissuration des noyaux, dont la compréhension est la clé pour optimiser l’étape de débourrage qui consiste en la fracturation et l’élimination des noyaux. Les résultats de cette thèse serviront par ailleurs à nourrir un modèle numérique simulant le débourrage des pièces. Différents modes de chargements mécaniques ont été étudiés : flexion, compression, cisaillement, push-out, fatigue, fluage ou encore compression œdométrique. Ils correspondent à différents types de sollicitations, avec ou sans confinement du noyau, et permettent de caractériser soit le cœur ou la surface du matériau. L’endommagement peut être suivi grâce à la réalisation de cycles de décharge-recharge. Dans tous les cas, le comportement mécanique du noyau est fortement dépendant des propriétés et de l’état du liant. Ainsi, la dégradation thermique induite par la coulée de l’aluminium liquide modifie et dégrade nettement les propriétés du noyau. Des parallèles peuvent ainsi être dressés entre les propriétés du liant, le comportement mécanique du matériau sable/résine et l’endommagement microstructural observé après rupture. / Better knowledge about the mechanical behavior of foundry sand cores is required in order to optimize the aluminum cylinder head production process. Sand cores allow the casting of complex shape metallic parts and are made of sand grains, bound with a resin in low proportion. Sand cores are subjected to high temperatures and complex mechanical load during the production process. This study aims at characterizing the thermomechanical behavior of sand cores under various loads depending on the binder proportion, the temperature and mostly the binder thermal degradation. Particularly, we focus on the cores damage and fracture mechanisms. The understanding of such phenomena could lead to an optimization of the decoring step, consisting in the fracture and removing of the core from the metallic part. Indeed, the results of this Ph.D. thesis will be used to implement a numerical model of the decoring process. Different kinds of mechanical loads have been studied: bending, compression, shear, push-out, fatigue, creep or also oedometric tests. They correspond to different kinds of load, with or without confining pressure and allow a characterization of the bulk or the surface of the material. The core damage is followed by mechanical tests with unload-reload cycles sequences. For all the cases, the core mechanical behavior is highly dependent on the binder properties and thermal degradation. For example, the thermal degradation induced by the aluminum casting modifies and degrades significantly the core properties. Analogies could be drawn between the binder properties, bonded-sand cores mechanical behavior and the evolution of the fracture surfaces.

<p>Liquid Chromatography (LC) and Capillary Electrophoresis (CE) are modern analytical techniques that play very important roles in many areas of modern science such as life science, biotechnology, biomedicine, environmental studies, and development of pharmaceutics. Even though these two techniques have existed and been subjected to studies for several decades, the developments of new separation materials for them are still very important till now in order to meet the different new demands for improvement from other disciplines in science.</p><p>In this doctoral thesis, several novel covalently bonded sulfobetaine type zwitterionic separation materials are synthesized for the application in LC and CE. These materials carry both positively charged quaternary ammonium groups and negatively charged sulfonic groups, which result in a very low net surface charge compared to conventional separation materials with only anionic or cationic functional groups. Consequently, it is possible to employ these materials for separation of different ionic species under mild conditions. The surface properties have also been characterized, mainly by elemental analysis, sorption isotherm, ζ-potential measurements, and spectroscopic methods.</p><p>By using packed zwitterionic columns for liquid chromatography, small inorganic anions or cations, and acidic or basic proteins can be independently and simultaneously separated in a single run using optimal sets of separation conditions. This is a unique property compared to conventional ionic separation material for LC. When fused silica capillaries coated with zwitterionic polymer are used for capillary electrophoresis, good separations can be achieved for solutes as different as inorganic anions, peptides, proteins, and tryptically digested proteins.</p>

Liquid Chromatography (LC) and Capillary Electrophoresis (CE) are modern analytical techniques that play very important roles in many areas of modern science such as life science, biotechnology, biomedicine, environmental studies, and development of pharmaceutics. Even though these two techniques have existed and been subjected to studies for several decades, the developments of new separation materials for them are still very important till now in order to meet the different new demands for improvement from other disciplines in science. In this doctoral thesis, several novel covalently bonded sulfobetaine type zwitterionic separation materials are synthesized for the application in LC and CE. These materials carry both positively charged quaternary ammonium groups and negatively charged sulfonic groups, which result in a very low net surface charge compared to conventional separation materials with only anionic or cationic functional groups. Consequently, it is possible to employ these materials for separation of different ionic species under mild conditions. The surface properties have also been characterized, mainly by elemental analysis, sorption isotherm, ζ-potential measurements, and spectroscopic methods. By using packed zwitterionic columns for liquid chromatography, small inorganic anions or cations, and acidic or basic proteins can be independently and simultaneously separated in a single run using optimal sets of separation conditions. This is a unique property compared to conventional ionic separation material for LC. When fused silica capillaries coated with zwitterionic polymer are used for capillary electrophoresis, good separations can be achieved for solutes as different as inorganic anions, peptides, proteins, and tryptically digested proteins.

Kaohsiung area has the excellent geographical position, eliminates has the deep water port which the transportation amount is among the best, also the international airport simultaneously has the shortest average distance with the neighbor country, not only the peripheral region correlation industry foundation is abundant, it really has the potential to develop "the Global Logistic Center" on behalf of Taiwan. But in the pass, Taiwan in both shore policy, the industrial policy, under the correlation law intriguing, creates the Kaohsiung double port area development to be unbalanced, also faces Mainland China and the Southeast Asia area, local city and so on and also South Korean Pusan¡¦s astringently challenge, therefore draining of the Kaohsiung double port competitive ability is becomes inevitably. Therefore, motive of this research, namely emphatically in: Kaohsiung has the sea and air double port condition, analyzes the region industry development and the global logistic tendency of, and establishes Kaohsiung to develop into the Global Logistic Center foundation.