Na construção de rodovias, as condições de umidade e densidade observadas na compactação são, geralmente, próximas daquelas correspondentes ao pico da curva de compactação obtida no ensaio Proctor. É sabido que variações ambientais no decorrer da vida do pavimento podem alterar, de maneira significativa, a umidade do subleito e dos seus componentes e assim, as suas propriedades resilientes. O objetivo principal desta pesquisa é avaliar a influência da variação da umidade pós-compactação no módulo de resiliência de solos de rodovias do interior paulista a partir de resultados de ensaios de laboratório. Foram coletados e caracterizados setenta e três solos, e, dentre estes, selecionados trinta para a etapa de estudo da variação da umidade pós-compactação, após a realização de ensaios MCT, difração de raios-x, microscopia eletrônica de varredura e azul de metileno para determinação da gênese. Os solos selecionados apresentam características distintas quanto à gênese, sendo metade laterítico e metade não-laterítico. Os corpos-de-prova foram compactados na umidade ótima e submetidos a processos de secagem e umedecimento e, posteriormente, realizados ensaios triaxiais cíclicos. Os resultados permitiram a modelagem do 'M IND.R' em função do estado de tensão para diferentes umidades e a avaliação da competência de alguns modelos matemáticos nesta representação. Estudou-se a influência da gênese e da granulometria sobre o valor do 'M IND.R' e avaliou-se a conseqüência da variação da umidade sobre este para solos lateríticos e não-lateríticos. Determinou-se uma expressão para estimar a variação do 'M IND.R' com a variação da umidade a partir do parâmetro k1, independentemente do estado de tensão. Pesquisou-se a existência de relações entre os parâmetros de regressão do modelo composto e os resultados dos ensaios de compressão simples e as propriedades físicas dos solos, de forma a permitir a estimativa do módulo de resiliência a partir do resultado de ensaios mais simples. Investigou-se a possibilidade de se utilizar as relações entre a variação do módulo tangente inicial com a variação da umidade para estimar os efeitos sobre o 'M IND.R'. / On road construction, the field compaction conditions are usually close to those determined from Proctor tests. Environmental variations may lead to changes in the pavement moisture and also changing its resilient properties. The main objective of this research is to study the influence of post-compaction moisture content variation on the resilient modulus of soils from São Paulo state pavements, using laboratory tests. To accomplish this objective, seventy three soils samples were collected and characterized. Among them, thirty samples were selected, after four different tests were carried out to determine the soils genesis, to study the post-compaction moisture content variation. Half of these selected soils are lateritic ones, and the other half are non-lateritic soils. The specimens were compacted at optimum moisture content and submitted to drying and moistening processes prior cyclic triaxial test to be carried out. The results allowed the resilient modulus modeling as a function at the stress state and the performance evaluation of five different models. The genesis and grain size distribution influence on the resilient modulus values were studied. The effects of moisture content variations on lateritic and non-lateritic soils were investigated. An expression to estimate the resilient modulus variations with the moisture variations was determined, independently of the stress state. The existence of relations of the compound model regression parameters with the results of unconfined compressive strength and soil properties were studied. The possibility of using the initial tangent modulus variations with the moisture variations to estimate the effects on the resilient modulus were also investigated.

Made available in DSpace on 2014-08-20T14:30:11Z (GMT). No. of bitstreams: 1 Tese_Cesar_Henrique_Zanchi.pdf: 1068579 bytes, checksum: 8e2ef86f128f91b16a71c1a2e41952f6 (MD5) Previous issue date: 2010-05-07 / This study evaluated the influence of surfactant dimethacrylates (SD) on the resin-to-dentin immediate and long term microtensile bond strength (μTBS) and characterized the interfacial micromorphology of hybrid layer of the experimental HEMA-free self-etching systems. Five experimental HEMA-free two step self-etching systems containing different surfactant dimetacrylates (SD) (Bis-EMA 10, Bis-EMA 30, PEG 400, PEG 1000 and PEG 400 UDMA) and a HEMA-containing systems (control) were formulated. Sixty bovine incisors were allocated into six groups according each experimental adhesive system used. The teeth had the superficial coronal dentins exposed and were restored and sectioned to obtain sticks randomly allocated into 3 storage periods: 24h, 6 and 12 months. Thereafter the specimens were subjected to the μTBS test. Immediate μTBS data were analyzed by One-way ANOVA and Tukey s test. Long term μTBS data were analyzed by Kruskall-Wallis and Dunn test (α = 0.05). Analysis of the adhesive-dentin interfaces were performed through scanning electron microscopy. Between the HEMA-free groups, the adhesive system formulated with PEG 400 UDMA produced the highest μTBS and was similar to HEMA-containing group. Specimens of the 24 hours of storage were statistically higher for all groups tested when compared those after 6 and 12 months storage. None difference was found between 6 months and 12 months storage for each group. All the adhesives systems presented similar partially demineralized hybrid layer (1.5-3.0 μm thickness) with well formed resin tags. All SD present reasonable μTBS, being the PEG 400 UDMA a promising monomer to be considered as HEMA substitute in adhesive systems compositions. / Este estudo avaliou a influência de dimetacrilatos surfactantes (DS) na resistência de união à dentina por microtração (RU), imediata e após armazenagem, além de caracterizar a micromorfologia da camada híbrida de sistemas adesivos experimentais autocondicionantes livres de HEMA. Foram formulados cinco sistemas adesivos autocondicionantes de dois passos livres de HEMA contendo diferentes DS (Bis-EMA 10, Bis-EMA 30, PEG 400, PEG 1000 and PEG 400 UDMA) e um sistema contendo HEMA, empregado como controle. Foi realizada a exposição da dentina superficial de sessenta incisivos bovinos posteriormente alocados em seis grupos experimentais de acordo com o sistema adesivo empregado. Os dentes foram restaurados e seccionados para obter espécimes (palitos) posteriormente divididos em três períodos de armazenagem: 24h, 6 e 12 meses. Após, os espécimes foram sujeitos ao teste de RU. Resultados de RU imediata foram analisados por ANOVA 1-fator e teste complementar de Tukey. Resultados de RU após envelhecimento foram analisados por Kruskall-Wallis e teste de Dunn (α = 0.05). Analises das interfaces de união dente-restauração foram realizadas através de microscopia eletrônica de varredura. Entre os grupos livres de HEMA, o sistema adesivo formulado com PEG 400 UDMA produziu maior RU e foi estatisticamente similar ao grupo controle contendo HEMA. Os espécimes testados após 24 horas de armazenamento apresentaram RU estatisticamente maior para todos os grupos quando comparados os espécimes testados após 6 e 12 meses de armazenagem. Não foram observadas diferenças significativas entre os grupos testados após 6 e 12 meses. Todos os sistemas adesivos apresentaram camada hibrida parcialmente desmineralizada (1.5-3 μm de espessura) com formação de prolongamentos resinosos. Em geral os sistemas adesivos demonstraram valores de RU satisfatórios, sendo o PEG 400 UDMA um monômero promissor para o desenvolvimento de sistemas adesivos livres de HEMA.

Background: Knowledge of the relationship between fat free mass (FFM) and strength capacity is not only useful in athlete coaching, but may also be important in developing clinical strategies for evaluating health in general populations. Sufficient skeletal muscle mass and strength are important factors for health and physical function. Bioelectrical impedance analysis (BIA) is a popular and clinically useful tool for assessing body composition. However, being able to simultaneously estimate whole body muscle strength without having to perform additional tests may prove useful in evaluating an individual’s health and physical function. Aim: The primary purpose of this study was to quantify the association between total body fat free mass percentage (TBFFM%) and relative strength in the isometric midthigh pull test (IMTP) and grip strength (GS) test in a healthy general young Swedish population. A secondary purpose was to investigate if there are any sex differences.  Methods: The design for this study was cross-sectional. The studied sample represented a general Swedish population of healthy young adults. Participants were asked to participate in testing on one occasion. Three tests were used for collecting data: BIA for data on FFM and both IMTP and hand dynamometer grip strength test for data on maximal force production. All tests were performed in the movement lab on Halmstad University campus. Statistical analyses were done using Pearson’s correlation and linear regression analysis. Results: Participants for this study consisted of healthy females (n=18) and males (n=17) aged 19-39. The primary findings of this study are that there are strong correlations between TBFFM% and relative strength (r = 0.621) in the IMTP test as well as relative GS (r = 0.705) on a whole-group level. The correlation between TBFFM% and relative GS was slightly stronger. Categorized by sex, we found strong positive correlations between TBFFM% and relative IMTP (r = 0.551) and relative GS (r = 0.596) for the female group and moderately strong correlations for the male group (relative IMTP r = 0.411; relative GS  r = 0.422).On a whole-group level, every unit increase in TBFFM% increases relative strength in the IMTP by 0.538N/kgBW (β = 0.538) and relative GS by 0.015 kg/kgBW (β = 0.015). Conclusion: TBFFM% was strongly associated with both relative IMTP strength and relative GS where the association was stronger for females than for males. TBFFM% values may be indicative of an individual's strength, which could be of value in a research setting.

Made available in DSpace on 2014-06-11T19:28:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-21Bitstream added on 2014-06-13T20:18:41Z : No. of bitstreams: 1 alonso_aa_me_sjc.pdf: 816482 bytes, checksum: 5e7f9255e591189fa6c1f9a1470015f7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho avaliou a influência de três diferentes métodos de fundição (maçarico e centrífuga elétrica - G1, indução eletromagnética - G2 e plasma - G3), sobre a interface de uma liga metálica de Pd-Ag-Sn e uma cerâmica odontológica de cobertura. Foram encerados para cada método de fundição 30 padrões em cera. Os padrões em cera foram incluídos e fundidos de acordo com as especificações de cada fabricante de equipamentos de fundição. Após o processo de sinterização da cerâmica, os corpos de prova (CP) foram divididos em dois subgrupos. Um subgrupo foi submetido diretamente ao ensaio mecânico de cisalhamento, e o outro recebeu ciclagem térmica e mecânica, seguido do ensaio mecânico de cisalhamento. Então, para cada método de fundição (n=24), metade dos CP receberam ciclagem térmica e mecânica (n=12), e a outra metade os CP não foram ciclados. Após o cisalhamento, os CP foram examinados em estereomicroscópio, para verificação do padrão de fratura. Os valores coletados durante o ensaio de cisalhamento receberam análise estatística, (ANOVA e teste de Tukey), com nível de significância de 5%. Os resultados mostraram os seguintes valores (média l desvio padrão), para os subgrupos sem ciclagem: 108,35 l 22,97 MPa para o maçarico; 103,64 l 28,28 MPa para a indução; 93,79 l 11,07 MPa para o plasma; para o sub grupo com ciclagens: 97,96 l 18,30 MPa para o maçarico; 62,34 l 11,26 MPa para a indução; e 58,10 l 10,66 MPa para o plasma. Conclui-se que os grupos Plasma com ciclagem e Indução com ciclagem apresentam médias dos resultados semelhantes e menores que os demais. / The aim of this study was to evaluate the three differents methods of melting (gas oxygen torch and eletrical centrifuge G1, Induction electrical centrifuge G2 e automated casting machine with gas argon - G3), between the interface of the Pd-Ag-Sn alloy, and a dental ceramic. Thirty standardized specimens were waxed for each method of melting. The specimens were included and melted in agreement with each manufacturer's melting equipments specifications. Following a feldspatic ceramic was applied over the metal copping, according to the manufacturers' instructions The specimens were divided in two subgroups. One subgroup was directly submitted to the shear bond strength test; and the other subgroup was thermo-cycled, mechanic-cycled, followed by the shear bond strength test. The fractured specimens were evaluated under a stereoscopic loup (20 X magnification), and the type of fracture recorded. The data collected during the shear bond strength test were submitted to ANOVA and Tukey's test statistical analysis with 5% level of significantly. The results showed the following values (mean l S.D.), for the sub groups without cycling: 108,35 l 22,97 MPa by gas oxygen torch and eletrical centrifuge, 103,64 l 28,28 MPa by Induction electrical centrifuge, 93,79 l 11,07 MPa by automated casting machine with gas argon and for the sub group with cycling 97,96 l 18,30 MPa by gas oxygen torch and electrical centrifuge, 62,34 l 11,26 MPa by Induction electrical centrifuge, and 58,10 l 10,66 MPa by automated casting machine with gas argon. Considering this study we can conclude that the automated casting machine with gas argon with cycling and Induction electrical centrifuge with cycling presents similar averages and lower than the others groups.

Une option à l'étude pour le recyclage des actinides mineurs consiste à en incorporer environ 10% à une matrice d'UO2. La présence de pores ouverts interconnectés au sein de ce combustible devrait permettre d'évacuer l'hélium et les gaz de fission pour prévenir le gonflement de la pastille et in fine son interaction avec la gaine qui l'entoure. La mise en oeuvre des actinides mineurs oblige à travailler en cellule blindée, à minimiser leur rétention et à proscrire les ajouts de produits organiques. L'emploi de particules fragmentables de quelques centaines de micromètres paraît une solution intéressante pour contrôler la microstructure des comprimés crus et ainsi maîtriser la porosité ouverte après frittage. L'étude consiste à suivre par émission acoustique la compaction de particules fragiles d'UO2 et à relier leurs caractéristiques à la porosité ouverte obtenue après frittage des compacts. Le signal acquis lors d'essais de cisaillement sur des granulés individuels et sur des compacts montre que l'émission acoustique autorise la détection de la fragmentation et permet l'identification d'une forme d'onde caractéristique. Les influences de la contrainte de compaction, de la distribution granulométrique initiale et de la cohésion interne des granulés, sur la tenue mécanique des compacts et sur la microstructure des frittés, en particulier sur la porosité ouverte sont analysées. Moyennant quelques précautions, l'émission acoustique, par sa capacité à déterminer le domaine de fragmentation des granulés pendant la mise en forme, paraît une technique prometteuse pour suivre la compaction de particules fragiles en vue de la fabrication de combustibles à porosité maîtrisée. / One of the options considered for recycling minor actinides is to incorporate about 10% to UO2 matrix. The presence of open pores interconnected within this fuel should allow the evacuation of helium and fission gases to prevent swelling of the pellet and ultimately its interaction with the fuel clad surrounding it.Implementation of minor actinides requires working in shielded cell, reducing their retention and outlawing additions of organic products. The use of fragmentable particles of several hundred micrometers seems a good solution to control the microstructure of the green compacts and thus control the open porosity after sintering.The goal of this study is to monitor the compaction of brittle UO2 particles by acoustic emission and to link the particle characteristics to the open porosity obtained after the compact sintering.The signals acquired during tensile strength tests on individual granules and compacts show that the acoustic emission allows the detection of the mechanism of fragmentation and enables identification of a characteristic waveform of this fragmentation.The influences of compaction stress, of the initial particle size distribution and of the internal cohesion of the granules, on the mechanical strength of the compact and on the microstructure and open porosity of the sintered pellets, are analyzed.By its ability to identify the range of fragmentation of the granules during compaction, acoustic emission appears as a promising technique for monitoring the compaction of brittle particles in the manufacture of a controlled porosity fuel.

The diploma thesis involves the design of certification static strength tests for the newly developed aircraft of the TL-Ultralight company. At the beginning of the work, the theory of aircraft testing is generally discussed with emphasis on static strength tests. Furthermore, an analysis of the requirements of the Czech regulation UL 2 and the German LTF-UL, which represent the certification basis for this aircraft, is performed. The requirements of regulations on the construction of the aircraft (or its individual parts) and the requirements for strength tests are discussed in detail. Based on the regulation and the provided calculation protocols, individual test cases and test plans of the wing, tail surfaces, engine bed, and chassis are calculated and prepared. In the end, the calculation of the rocker system and the basic design of jigs are performed.

La présente étude porte sur le comportement mécanique de deux types de supports de catalyseurs utilisés industriellement en hydrotraitement des résidus. Ces supports extrudés, fabriqués par IFPEN, sont constitués d’alumine de transition γ avec un taux de porosité proche de 70%. La porosité du premier matériau est uniquement constituée de mésopores (< 50 nm). La porosité du second matériau est constituée de mésopores et de macropores (jusqu’à 20 µm). Les niveaux de sollicitation en service étant très peu connus, cette étude s’attache à décrire de manière précise et exhaustive le comportement mécanique de ces supports sous une large gamme de sollicitations, et à identifier les différents mécanismes de ruine possibles. L’objectif final est de mieux comprendre les relations entre les paramètres microstructuraux et les propriétés mécaniques afin d’identifier des leviers d’amélioration de la tenue mécanique des supports. Dans un premier temps, une méthodologie adaptée de caractérisation mécanique est établie. Le comportement des supports est étudié d’une part en traction, à l’aide d’essais de flexion trois points et d’écrasement diamétral, et d’autre part, en compression sous différents taux de triaxialité, à l’aide d’essais de compression uniaxiale et hydrostatique et d’essais de micro-indentation sphérique. Les différents mécanismes responsables de la ruine des supports sont identifiés au moyen de techniques d’imagerie telles que la microscopie électronique à balayage et la micro-tomographie à rayons X. En traction, le comportement est fragile avec l’amorçage de la rupture sur un défaut critique. En compression, une transition fragile / quasi-plastique du comportement est observée avec l’augmentation du taux de confinement. Cette quasi-plasticité s’exprime en particulier à travers un phénomène de densification de la macroporosité. Dans un deuxième temps, un critère de rupture est identifié pour chaque type de matériau en vue de représenter sur une même surface de charge les différents types de comportement et phénomènes physiques observés. Cette identification est réalisée en couplant les essais d’indentation sphérique à une analyse numérique. Des critères faisant intervenir la pression hydrostatique permettent de rendre compte de la forte dissymétrie du comportement des matériaux en traction et en compression. Enfin, dans un souci de se rapprocher des sollicitations subies par les supports de catalyseurs dans un réacteur en service, le comportement d’un empilement de supports est étudié en compression œdométrique. L’analyse de cet essai par tomographie à rayons X permet de déterminer les différents mécanismes de ruine intervenant au sein d’un empilement, en particulier ceux responsables de la génération de fines. Les résultats illustrent la pertinence de la caractérisation en flexion et en indentation des supports de catalyseurs seuls pour prévoir leur comportement au sein d’un empilement en compression. / In this work, we study the mechanical behaviour of two types of catalysts supports produced by IFPEN and industrially used in residues hydrotreating. Those extruded supports are made of transition γ-alumina with about 70% of porous volume. The first material’s porosity is exclusively composed of mesopores (< 50 nm). The porosity of the second material is composed of both mesopores and macropores (up to 20 µm). Because of the limited knowledge of the stress fields in embedded catalysts supports in use in a reactor, this study aims at precisely and exhaustively describing the mechanical behaviour of those supports under a wide range of stresses, and identifying the possible damage mechanisms. The final objective is to better understand the influence of microstructural parameters on the mechanical properties of the supports in order to propose some leads about how to improve their mechanical strength. First, an adequate mechanical characterization methodology is set. On one hand, the tensile mechanical behaviour of the supports is studied with three-point bending and diametrical crushing tests. On the other hand, their compressive behaviour under various triaxiality rates is characterized in uniaxial and hydrostatic compression, and by spherical micro-indentation. The different damaging mechanisms are identified by imaging techniques such as scanning electronic microscopy and X-ray micro-tomography. Under tensile stresses, the supports exhibit a brittle behaviour and fracture initiates at a critical flaw. Under compressive stresses, a brittle/quasi-plastic transition is observed with increasing the triaxiality rate. The quasi-plasticity is mainly due to the densification of the macroporosity. The second part of the study consists in identifying, for each material, a fracture criterion able to represent every types of behaviour and physical phenomena observed on the same yield surface. This identification is achieved by coupling the spherical indentation tests to a numerical analysis. Fracture criteria involving hydrostatic pressure are well suited to describe the highly dissymmetric mechanical behaviour of the materials in tension and in compression. The last part of this work aims at studying the mechanical behaviour of a stack of supports under œdometric compression in order to produce stress fields more representative of those existing within the supports stacked in a reactor. This test is analysed by X-ray tomography, which allows us to determine/acknowledge the different damaging mechanisms involved in fragments and fines generation. The results illustrate the suitability of the bending and indentation tests to characterize the mechanical properties of a single support and relate them to its mechanical behaviour in a stack of supports under compression.