A crescente preocupação ambiental e a atual crise energética fazem com que indústrias, de um modo geral, intensifiquem esforços para maximização de processos de produção e reutilização de subprodutos gerados. Na siderurgia a produção do aço é realizada por meio da extração do minério de ferro adicionando-se fundentes, gerando como subproduto uma ganga em forma de escória de alto forno. Na presente pesquisa foram compostas misturas de concreto compactado com rolo CCR visando o emprego como base de pavimentos, utilizando três diferentes materiais de granulometria miúda: areia natural, areia industrial e escória granulada de alto forno (com dimensão máxima de 4,8 mm) nas quantidades de 50 % e 100 %; para fins de análise da influência destas diferentes areias foram confeccionados corpos de prova cilíndricos e prismáticos moldados na umidade ótima e no ramo seco da curva de compactação. Foram investigados parâmetros referentes à umidade de compactação, massa específica, resistências à tração indireta e à tração na flexão, módulos de elasticidade por pulso ultrassônico, além de módulos de elasticidade estáticos obtidos a partir de curvas tensão-deformação e por analogia de Möhr (medida de flecha em vigotas em flexão). Visando avaliar a aplicabilidade dos CCR estudados, em especial aquele com escória, foi utilizado o programa computacional MnLayer (para análise de tensões em pavimentos asfálticos) empregando camada de base rígida em CCR para estruturas de pavimentos sujeitos à ação de cargas do tráfego de veículos rodoviários, portuários e aeroportuários, observando a influência dos três tipos de agregados miúdos no nível de tensões da camada cimentada, o que depende em grande parte do módulo de elasticidade da camada de base. Observou-se queda nas resistências dos CCR quando da incorporação de 50 % ou 100 % de escória granulada; por outro lado, essas misturas apresentaram ganhos de resistência em idades mais avançadas em comparação a misturas que empregaram areias natural ou industrial. O módulo de elasticidade dos CCR, com a presença da escória, parcial ou total como fração areia, em geral decresceu à exceção de seu emprego em conjunto com areia natural. As misturas com escória granulada, do ponto de vista de análise mecanicista, resultaram em exigências de maiores espessuras do material, o que não pode fazer tal mistura economicamente viável em qualquer situação, para os casos de misturas com 100 % de escória granulada de alto forno e com fração mista de areia natural e escória. / The increasing environmental concerns as well as energy sources shortage leads industry to consider both optimization of production processes and sustainable use and disposal of its by-pass products. In siderurgical steel manufactures the most common by-pass product is the blast furnace slag with emphasis to its granulated shape. This study considered the evaluation of rolled compacted concretes (RCC) mixtures containing natural or industrial sands as well as such slags at 50% and 100% (with maximum diameter of 4.8 mm) as candidates for pavement base layers. The analysis considered laboratory compaction tests in order to verify the influence of such sands on concrete physical parameters as bulk density and optimum moisture content. Evaluation of mechanical parameters as indirect tensile strength, flexural strength, ultrasonic modulus of elasticity and static modulus of elasticity were carried out as part of the study. Through mechanistic analysis using the elastic layered theory-based computational program MnLayer it was possible to verify implications of each RCC mixture design on pavement thickness and tensile stresses in cemented base layers, in consideration of highway, harbor and airport vehicles. Loss of resistance was verified for RCC mixtures at 50% and 100% slag sand; on the other hand such mixtures have improved its strengths at advanced ages (180 days) compared to the other sands. The modulus of elasticity also decreased for mixtures containing slag sands with exception to the blend of natural and slag sand. Under the mechanistic stand point slag sand mixtures requires thicker base layers in pavements that could lead, depending on several factors, to less cost-effective results in the case of 100% slag sands mixtures and blend (50%-50%) natural and slag sands mixtures.

Os processos de reciclagem e produção de agregados reciclados provenientes de resíduos de construção e demolição (RCD) estão se consolidando no Brasil, mas o seu emprego não ocorre na mesma proporção. A utilização desses em pavimentação, principalmente em camadas de base e sub-base, é considerada mais conveniente que em outras áreas, visto que não necessita de procedimentos avançados de reciclagem e utiliza os mesmos processos construtivos que agregados já consagrados, como britas graduadas. Entretanto, as recomendações normativas existentes remetem à caracterização dos agregados, sendo que as alusões ao seu comportamento mecânico são idênticas às impostas para britas graduadas. Além disso, a literatura existente é limitada frente a outros materiais alternativos, o que implica restrições ao seu emprego. Buscando atenuar essas incertezas, essa pesquisa tem como objetivo analisar o comportamento mecânico de agregados reciclados provenientes de RCD, de modo a identificar suas principais características e fornecer parâmetros de anteprojeto para o dimensionamento de pavimentos que utilizam esse material como camadas de suporte. Para isso, a primeira etapa comportou uma análise dos processos de beneficiamento dos agregados reciclados, de modo a identificar como influem nas suas características, o que foi alcançado concomitantemente a segunda etapa, que consistiu na análise dos agregados por meio de ensaios específicos de caracterização física e química. A terceira e principal etapa baseou-se na análise do comportamento mecânico, que além da determinação em equipamentos convencionais, também utilizou um equipamento triaxial de grande porte que comporta corpos de prova de 25 x 50 cm, permitindo a utilização da distribuição a ser empregada em campo. Essa etapa iniciou pela análise da compactação, realizada com curvas granulométricas e modos de umedecimento distintos, onde os mais promissores foram escolhidos para verificar a influência do método de compactação, sendo ele dinâmico ou vibratório. Após essas determinações, a análise concentrou-se no módulo de resiliência, na resistência ao cisalhamento e na deformação permanente, sendo que as evoluções da deformação permanente foram classificadas segundo a teoria do Shakedown. Os resultados demonstraram que a compactação causa a quebra de agregados, porém essa é menor quando utilizada compactação dinâmica. Os RCD apresentaram bom comportamento em relação deformações elásticas, com módulo de resiliência semelhantes aos apresentados por britas. Dado a diminuição de partículas lamelares causada pela quebra durante o processo de compactação, os valores mais representativos do ângulo de atrito e do intercepto coesivo foram 41° e 60 kPa, respectivamente. As análises das deformações realizadas em multiestágios demonstraram que, se utilizados em pavimentos com baixo de volume de tráfego, para razões de tensões σd / σ3 < 2 e tensões desvio σd ≤ 210 kPa, bases compostas de RCD não vão desenvolver deformações plásticas iniciais excessivas e o material vai responder elasticamente. Além disso, essas bases estão seguras contra falhas de cisalhamento. Em suma, as análises indicam que os RCD podem ser utilizados como materiais para bases e sub-bases de pavimentos de baixo volume de tráfego, dando um destino nobre a uma matéria-prima renovável e facilmente encontrada, que na maioria das vezes é desperdiçada e cuja geração aumenta constantemente. / Construction and Demolition Waste (CDW) recycling processes are consolidating in Brazil, but their use does not occur in the same proportion. The application of such in pavement, especially in base and sub-base layers, it is considered more convenient than in other areas because it does not require advanced recycling procedures and using the same constructive processes which aggregates already established, as graded gravel. However, existing normative recommendations refer to the characterization of the aggregates, and the allusions to their mechanical behavior are identical to those imposed on graded gravel. Moreover, the existing literature is limited compared to other alternative materials, implying restrictions on its use. Seeking to mitigate these uncertainties, this research aims to analyze the mechanical behavior of recycled aggregates from CDW, in order to identify its main characteristics and provide parameters for draft design of pavements that using this material as a support layer. For this, the first step involved an analysis of the aggregates recycling procedures, in order to identify the influence of this process in their characteristics, which were concomitantly reached the second stage consisting in the analysis of aggregate by specific tests of physical and chemistry characterization. The third and main step was based on the analysis of mechanical behavior, which besides determining in conventional equipment also utilized a large triaxial device that carries specimens of 25 x 50 cm, allowing the use of the distribution to be employed in field. This step began by analyzing the compaction performed with gradation curves and distinct modes of moistening, where the most promising were chosen to investigate the influence of compaction method, either dynamic or vibration. After these determinations, the analysis focused on the resilient modulus, shear strength and permanent strain, and the evolution of permanent strain were classified according to the theory of Shakedown. The results showed that compaction causes the aggregates break, but this is less when used dynamic compaction. The CDW had good behavior relative elastic strains, with resilient modulus similar to those presented by gravel. Since the decrease of lamellar particles caused by breakage during the compaction process, the most representative values of the friction angle and cohesive intercept were 41° and 60 kPa, respectively. The analysis of the permanent strain carried out in multistage demonstrated that if used in pavements with low traffic volume, for reasons of stress σd / σ3 < 2 and deviator stress σd ≤ 210 kPa, compound bases CDW will not develop excessive initial plastic strain and the material will respond elastically. In addition, these bases are secure against shear failure. In essence, the analysis indicates that the CDW can be used as materials for bases and sub-bases of low volume traffic floors, giving a noble destiny to a renewable raw material and easily found that most of the time is wasted and whose generation is constantly increasing.

Ce travail s’inscrit dans un contexte de développement des réacteurs de quatrième génération. Il concerne plus particulièrement la partie composite du gainage tubulaire de type sandwich envisagé par le CEA pour les réacteurs RNR-NA/Gaz. Le renfort est mis en forme par tressage et l’étude se focalise sur des composites tressés interlocks. Ces structures relativement nouvelles nécessitent une caractérisation mécanique poussée. Deux protocoles expérimentaux ont été développés permettant la réalisation d’essais de traction et de pression interne sur tube. Trois textures différentes ont ainsi été caractérisées. En parallèle un modèle multi-échelle a été mis en place permettant de relier la microstructure aux propriétés mécaniques du tube. Ce modèle est validé dans le domaine élastique sur une des textures caractérisées. Une première approche de l’endommagement de la structure est abordée et une amélioration possible du protocole est proposée. / This work is part of the development of the IVth generation of nuclear reactors. It relates more precisely to the composite portion of the sandwich type tubular cladding considered by the CEA for RNR-NA/Gaz type reactors. The texture is formed by a braiding technique and the study focuses on interlocks braided composite. These relatively new structures require extensive mechanical characterization. Two experimental protocols were developed to conduct tensile and internal pressure tests on tubes. Three different textures have been characterized. In addition, a multi-scale model was developed to connect the microstructure of the tube to its mechanical properties. This model is validated for the elastic behavior of a characterized texture. A first approach to the damage in the structure is proposed and a possible improved protocol is discussed.

Orientador: Jorge Luís Akasaki / Resumo: O contexto mundial de preocupação em relação ao meio-ambiente, seu uso desenfreado e a emissão dos gases estufa, principalmente a emissão de dióxido de carbono destacou a importância da pesquisa para se buscar novas alternativas sustentáveis nos meios de produção, dentre eles se encaixa a indústria do cimento Portland. A proposta deste estudo é uma nova alternativa sustentável para a construção civil, estudando a cinza de folha de bambu (CFB) como material pozolânico para ser utilizado como substituição parcial do cimento Portland. A cinza de folha de bambu foi produzida através de um processo de autocombustão sem temperatura controlada, e foi caracterizada física e quimicamente através dos ensaios de Fluorescência de Raio – X (FRX), determinação do teor de sílica amorfa, Difratometria de Raio – X (DRX), Granulometria a Laser, Microscopia Eletrônica de Varredura por Emissão de Campo (FESEM), Espectroscopia de Infravermelho por Transformada de Fourier (FTIR) e Analise Termogravimétrica (TGA). Sua reatividade foi analisada através dos ensaios de condutividade elétrica e pH, ensaio de Frattini e pastas de Cal/CFB e Cimento/CFB, as quais foram submetidas aos ensaios de FTIR, TGA e FESEM. Para avaliar sua influência na argamassa no estado fresco e endurecido, foram realizados os ensaios de índice de consistência e o ensaio de resistência à compressão, comparando-se as argamassas com substituição parcial do cimento à uma argamassa controle, sem adição mineral. Já a influência da ci... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The global context of concern for the environment, its unrestrained use and emission of greenhouse gases, especially the emission of carbon dioxide, highlighted the importance of research to find new sustainable alternatives in the means of production, among them, the Portland cement industry. The proposal of this study is a new sustainable alternative for civil construction, studying bamboo leaf ash (BLA) as pozzolanic material to be used as partial replacement of Portland cement. The bamboo leaf ash was produced by a process of autocombustion without temperature control, and was characterized physically and chemically by means of X - Ray Fluorescence (FRX), determination of the amorphous silica content, X - Ray Diffractometry (XRD), Laser Granulometry, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The reactivity analysis was carried out by means of electrical conductivity and pH measurements, Frattini analysis and calcium hydroxide / CFB and Cement / CFB pastes, which were assessed by FTIR, TGA and FESEM analysis. In order to evaluate its influence on the mortar in the fresh and hardened states, the tests of consistency index and compressive strength were carried out, comparing mortars with cement partial replacement with a control mortar, without mineral addition. The influence of the ash on durability was analyzed by means of mercury intrusion porosimetry analysis (MIP) and acid ne... (Complete abstract click electronic access below) / Mestre

Depuis plus de 60 ans, les résines composites à usage dentaire n’ont cessé d’évoluer vers des matériaux toujours plus fonctionnels et esthétiques. Toutefois, l’obtention du matériau de restauration idéal présentant des propriétés mécaniques et physico-chimiques optimales reste encore aujourd’hui un défi de taille. La nature et la proportion des monomères, le type, la taille et le taux de charges, la qualité des liens entre charges et matrice et la présence de porosités au sein des matériaux apparaissent comme des éléments pouvant influencer ces propriétés. Afin d’avancer dans le compréhension de l’impact de ces différents facteurs, plusieurs études ont été entreprises à l’aide de trois résines composites commerciales de viscosités différentes : une résine de viscosité élevée (Filtek P60 – 3M ESPE), une résine de viscosité moyenne (Grandio – Voco) et une résine de viscosité faible (Filtek Supreme XTE – 3M ESPE). L’influence de la manipulation clinique des matériaux sur le taux et le volume des porosités a été évaluée à l’aide de la tomographie 3D à rayons X. La manipulation augmente le pourcentage et diminue le volume moyen des porosités. En outre, plus le matériau est fluide et plus il présente de porosités en son sein. Deux groupes d’échantillons ont été réalisés afin d’évaluer l’influence de la porosité sur le comportement mécanique et physico-chimique des matériaux : l’un à partir des matériaux simplement extrudés des seringues et l’autre au sein duquel nous avons réalisé une adjonction artificielle de porosités. La contrainte de polymérisation à été déterminée à l’aide d’une machine de traction, l’absorption/solubilité a été mesurée en respectant le cadre ISO 4049, le comportement mécanique vrai a été évalué en traction à l’aide du système VidéoTractionTM, les comportements apparents en compression et flexion ont été étudiés respectivement à l’aide d’une machine de compression et d’une machine de flexion 3 points. Les différents constituants organiques et minéraux apparaissent comme des éléments déterminants dans le comportement physico-chimique et mécanique des matériaux. La porosité initiale est également un facteur prépondérant dans l’explication dudit comportement. Son influence n’est cependant pas proportionnelle à son taux puisque l’ajout de porosités artificielles n’influence pas significativement les résultats / For the past 60 years, dental resin composites have been constantly evolving, becoming increasingly functional and aesthetic materials. However, obtaining the ideal dental restorative material, with optimum mechanical and physicochemical properties, is still a significant challenge today. The nature and proportion of the monomers, the type, size and content of fillers, the quality of the bonds between the fillers and the matrix and the presence of porosities inside materials all emerge as aspects that can influence these properties. To improve our understanding of the impact of these various factors, a number of studies have been undertaken using three commercially-available resin composites with different viscosities: one high-viscosity resin (Filtek P60 – 3M ESPE), one moderate-viscosity resin (Grandio – Voco) and one low-viscosity resin (Filtek Supreme XTE – 3M ESPE). The influence of clinical handling of materials on the rate and volume of porosities has been evaluated by 3D X-ray computed tomography. Handling increases the porosity percentage and reduces the average porosity volume. Furthermore, the more flowable the material is, the more porosities it has within it. Two groups of samples were prepared in order to evaluate the influence of porosity on the mechanical and physicochemical behavior of materials: one group of samples consisted of materials simply extruded from syringes, while additional porosities were added artificially in the other samples. The polymerization stress was determined using a tensile testing machine, the absorption/solubility was measured in accordance with ISO 4049, the true tensile mechanical behavior was assessed using the VidéoTractionTM system, and the apparent compressive and flexural behaviors were studied using a compression test machine and a 3-point flexural test machine, respectively. The various organic and mineral components appear to be key elements in the physicochemical and mechanical behavior of materials. The initial porosity is also a predominant factor in terms of explaining this behavior. However, its influence is not proportional to its rate, since the addition of artificial porosities does not significantly affect the results

L’utilisation d’un composite Carbone/Carbone 2D est envisagée pour des pièces de structure, travaillant entre 150 et 400°C, dans l’aéronautique civile. Dans ce domaine de température, la durabilité de ces matériaux n’est pas connue car ils n’ont jamais été développés pour de telles applications. Une première approche a permis de corréler la réactivité chimique des constituants élémentaires (fibres et matrices) à leur état d’organisation structurale. Les vieillissements réalisés sur matériau composite ont ensuite mis en évidence qu’un faible taux d’oxydation pouvait conduire à un abaissement significatif des propriétés mécaniques résiduelles. Les fissures et les décohésions consécutives au procédé d’élaboration conduisent à une oxydation préférentielle du composé le plus réactif et à la ruine prématurée du composite par délaminage. L'évolution des propriétés de ce matériau sur de longues durées est finalement discutée afin d’évaluer sa capacité à remplacer les matériaux métalliques dans des pièces aéronautiques. / A 2D Carbon/Carbon composite is envisaged for structural parts, operating between 150 and 400°C, in civil aircraft. In this temperature range, the durability of these materials remains unknown because they have never been developed for this kind of applications. A first approach allowed us to correlate the chemical reactivity of the elemental constituents (fiber and matrix) to their structural organization. Then, thermal ageing tests performed on the composite material have demonstrated that a low rate of oxidation could be responsible to a significant reduction of residual mechanical properties. Cracks and fiber/matrix debonding resulting to the elaboration process create an extended pathway to a preferential oxidation of the most reactive compound. This latter is followed by a premature failure by delamination. The reduction of the material properties over long periods is finally discussed in order to evaluate its ability to replace metallic materials in aircraft structural parts.

A strategic research area today is development of polymericproducts made from renewable sources. The ways of utilizingrenewable sources studied in this thesis are using 1)prepolymers obtained by steam treatment of wood and 2) monomersobtainable by fermentation of agricultural products. Novel hemicellulose-based hydrogels were prepared by usingprepolymers obtained from steam treatment of spruce.Hemicellulose was first modified with well-defined amounts ofmethacrylic functions. Hydrogels were then prepared by radicalpolymerization with 2-hydroxyethyl methacrylate orpoly(ethylene glycol) dimethacrylate to form hydrogels. Theradical polymerization reaction was carried out in water usinga redox initiator system. The hydrogels were in generalelastic, soft and easily swollen in water. Frequency sweeptests indicated that the hydrogel system displayed prevailingsolid-like behavior. Comparison of the hemicellulose-basedhydrogels with pure poly(2-hydroxyethyl methacrylate)-basedhydrogels showed that it was possible to preparehemicellulose-based hydrogels with properties similar to thoseof pure poly(2-hydroxyethyl methacrylate)-based hydrogels. Polyester-based materials were prepared by using themonomers 1,3- propanediol and succinic acid obtainable byfermentation. α,ω-Dihydroxyterminatedoligomeric polyesters produced by the thermal polycondensationof 1,3-propanediol and succinic acid were chain-extended toobtain sufficiently high molecular weight. Depending on thechain-extension technology adopted, poly(ester carbonate)s orpoly(ester urethane)s were obtained. In the case of poly(estercarbonate)s, the chain-extended products ofα,ω-dihydroxyterminated oligomeric copolyesters werealso produced using 1,3-propanediol/1,4-cyclohexanedimethanol/succinic acid mixtures toimprove thermal and mechanical properties. Segmented poly(esterether carbonate)s fromα,ω-dihydroxyterminated oligo(propylenesuccinate)s and poly(ethylene glycol) were also synthesized toincrease the hydrophilicity. Molecular weights and polydispersity were analyzed by SECfor all materials. Their structures were also identified by NMRspectroscopy (1H NMR and 13C NMR). All characterizations werein agreement with the proposed structures. Thermal parameterswere characterized by DSC. Tensile testing anddynamic-mechanical tests were performed and in additionpreliminary processing trials were carried out in some cases.The results demonstrate the feasibility of using monomersderived from renewable sources to build up new polymericstructures endowed with a variety of physical and mechanicalproperties.

<p>A strategic research area today is development of polymericproducts made from renewable sources. The ways of utilizingrenewable sources studied in this thesis are using 1)prepolymers obtained by steam treatment of wood and 2) monomersobtainable by fermentation of agricultural products.</p><p>Novel hemicellulose-based hydrogels were prepared by usingprepolymers obtained from steam treatment of spruce.Hemicellulose was first modified with well-defined amounts ofmethacrylic functions. Hydrogels were then prepared by radicalpolymerization with 2-hydroxyethyl methacrylate orpoly(ethylene glycol) dimethacrylate to form hydrogels. Theradical polymerization reaction was carried out in water usinga redox initiator system. The hydrogels were in generalelastic, soft and easily swollen in water. Frequency sweeptests indicated that the hydrogel system displayed prevailingsolid-like behavior. Comparison of the hemicellulose-basedhydrogels with pure poly(2-hydroxyethyl methacrylate)-basedhydrogels showed that it was possible to preparehemicellulose-based hydrogels with properties similar to thoseof pure poly(2-hydroxyethyl methacrylate)-based hydrogels.</p><p>Polyester-based materials were prepared by using themonomers 1,3- propanediol and succinic acid obtainable byfermentation. α,ω-Dihydroxyterminatedoligomeric polyesters produced by the thermal polycondensationof 1,3-propanediol and succinic acid were chain-extended toobtain sufficiently high molecular weight. Depending on thechain-extension technology adopted, poly(ester carbonate)s orpoly(ester urethane)s were obtained. In the case of poly(estercarbonate)s, the chain-extended products ofα,ω-dihydroxyterminated oligomeric copolyesters werealso produced using 1,3-propanediol/1,4-cyclohexanedimethanol/succinic acid mixtures toimprove thermal and mechanical properties. Segmented poly(esterether carbonate)s fromα,ω-dihydroxyterminated oligo(propylenesuccinate)s and poly(ethylene glycol) were also synthesized toincrease the hydrophilicity.</p><p>Molecular weights and polydispersity were analyzed by SECfor all materials. Their structures were also identified by NMRspectroscopy (1H NMR and 13C NMR). All characterizations werein agreement with the proposed structures. Thermal parameterswere characterized by DSC. Tensile testing anddynamic-mechanical tests were performed and in additionpreliminary processing trials were carried out in some cases.The results demonstrate the feasibility of using monomersderived from renewable sources to build up new polymericstructures endowed with a variety of physical and mechanicalproperties.</p>

Dans le cadre de ce travail de thèse nous nous sommes intéressés à deux pathologies fémoro-acétabulaires dont la pathogénie semble liée aux « conditions biomécaniques » locales. La première partie de cette thèse était consacrée à l’analyse de l’influence de l’anatomie osseuse sur l’apparition de l’ostéonécrose aseptique de la tête fémorale. Nous avons réalisé des analyses analytique de l’anatomie des patients souffrant d’ONA (notre hypothèse était que nous retrouverions un profil anatomique particulier chez les patients souffrant d’ONA par rapport à la population générale.Nos résultats démontrent que les patients souffrant d’ONA présentent fréquemment une anatomie particulière. Notre modèle en éléments finis de la hanche de dix patients souffrant d’ONAi, a permis de valider notre hypothèse puisqu’il existe un recouvrement quasi-parfait, entre la zone de nécrose osseuse et celle supportant les contraintes fémoro-acétabulaires. L’hypothèse selon laquelle une pathogénie mécanique puisse être responsable du développement l’ostéonécrose aseptique de la tête fémorale est vérifiée par nos travaux.Dans la seconde partie de cette thèse nous avons décrit le rôle mécanique du LA par une évaluation multimodale combinant analyse cinématique,de contraintes fémoro-labrales et enfin analyse en éléments finis. Les résultats de ces études ont permis de constater que le LA se déforme lors du mouvement reflétant une transmission de contraintes fémoro-labrales lors du mouvement d’abduction. Ces contraintes ont pu être enregistrées à l’aide de capteurs piezo-resistifs, elles augmentent lors du mouvement d’abduction. Ces éléments ont été confirmés par notre modèle en éléments finis. / As parts of this thesis we focused on two femoro-acetabular diseases whose pathogenesis appears to be related to "biomechanical local conditions". The first part of this thesis was devoted to analyze the influence of bony anatomy on the development of aseptic osteonecrosis of the femoral head. We thus aimed to analyze ONA patients’ anatomy in a matched-controlled fashioned study. Our results demonstrate that patients with ONA often present a particular anatomy. A finite element model of ten iONA hips validated our hypothesis since we found an overlap between bone necrosis area and femoro-acetabular strains bearing area. The assumption that a mechanical pathogenesis may be responsible for ONA development has been confirmed by our results.If the relationship between bony anatomy and bone disease is quite intuitive, acetabular labrum involvement (AL) in the regulation of femoro-acetabular mechanical conditions is unclear. The mechanical role of the AL is widely controversial, though some authors attributed, AL, a key role in hip joint’s mechanics, others advocated its complete resection in case of painful traumatic tears. We tried to demonstrate AL’s mechanical role in a multimodal analysis combining kinematic, strains and finite element analysis. The AL deforms during abduction movement reflecting femoro-labral strains’ transmission. Those strains have been recorded using piezo-resistive sensors, they increase during adduction to abduction movement. These elements were confirmed by our finite element model: labral resection changed the Femoro-acetabular strains to the detriment of cartilage surfaces.

Lors de la dernière décennie, l’hydrure de magnésium est apparu comme le candidat le plus intéressant pour le stockage solide de l’hydrogène à grande échelle. La présente étude s’est intéressée au gonflement irréversible de composites à base d’hydrure de magnésium durant les cycles d’hydruration/déshydruration ainsi qu’à l’évolution de leurs propriétés mécaniques.Les expériences de dilatométrie in-situ et les caractérisations microstructurales (MEB,granulométrie), menées sur des échantillons de MgH₂co-broyés avec des additifs devanadium ou Ti-V-Cr ont montré que la coalescence des particules nanométriques favorise la formation de larges agglomérats qui induisent une augmentation de la porosité et qui expliquent le gonflement irréversible des composites.Les tests de nano-indentation ont montré une augmentation du module de Young de plus de 30 % après 10 cycles d’hydruration/déshydruration. Les mesures de la dureté Vickers sur des pastilles de MgH2 sans additif ont permis d’estimer sa dureté en fonction de la densité relative. Ainsi la dureté d’une pastille qui aurait une densité proche de la densitéthéorique (95 %) a été extrapolée à 0.58 GPa. / The last decade the magnesium hydride stood out as the most attractive candidatefor solid storage of hydrogen at large scale. The main subject of this study is thephenomenon of irreversible swelling of the composites based on magnesium hydride, duringthe hydriding/dehydriding cycles as well as the evolution of their mechanical properties.In-situ dilatometry measurements and the microstructural characterizations (SEM,granulometry) were performed on magnesium hydride samples co-milled with vanadium orTi-V-Cr additive. The results reveal that the coalescence of nanometric particles tends tocreate large agglomerates, which induce an increase in porosity, and explain the progressiveswelling of composites.The nanoindentation tests performed on compacted pellets show an enhancement ofabout 30 % of the Young modulus after 10 cycles. From the Vickers hardness measured oncompacted powders, the hardness of a highly densified magnesium hydride wasextrapolated to 0.58 GPa, which shows that the magnesium hydride is harder thanmagnesium.