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Caracterização miofuncional clínica e eletromiográfica de pacientes adultos com trauma de face / Oral-motor and electromyographic caracterization of patients submitted to open and closed reductions for facial fracturesAmanda Pagliotto da Silva 03 December 2015 (has links)
Objetivo: realizar a caracterização do sistema miofuncional orofacial de indivíduos adultos com fraturas de face, que foram submetidos à procedimentos cirúrgicos distintos para a correção das fraturas (redução aberta e fechada). Métodos: 57 participantes divididos em três grupos: G1- composto por 19 indivíduos submetidos a redução aberta de pelo menos uma das fraturas faciais; G2- composto por 19 indivíduos submetidos a redução fechada da fratura; GC - 19 indivíduos voluntários saudáveis, sem alterações no sistema miofuncional orofacial. Todos os participantes foram submetidos à avaliação que consistiu na aplicação de um protocolo clínico para a avaliação da motricidade orofacial, a amplitude dos movimentos mandibulares e a avaliação da musculatura mastigatória por meio da eletromiografia de superfície (EMGs). Resultados: os resultados indicaram que para avaliação clínica da motricidade orofacial, ambos os grupos com fratura de face se diferenciaram do grupo controle, apresentando prejuízo na mobilidade dos órgãos fonoarticulatórios e nas funções de mastigação e deglutição. Os grupos com fratura de face não se diferenciaram neste item da avaliação. Quanto às medidas de amplitude mandibular, os grupos com fratura de face também se diferenciaram do grupo controle, apresentando maior restrição da mobilidade mandibular. Nesta etapa da avaliação, o grupo submetido à redução fechada da fratura apresentou maior amplitude de movimentos, se comparado ao grupo submetido à redução aberta da mesma, principalmente para a medida de abertura oral máxima. Na avaliação eletromiográfica dos músculos mastigatórios, o grupo submetido à redução aberta da fratura apresentou menor ativação muscular se comparado aos demais grupos. Ambos os grupos com fraturas de face se diferenciaram significantemente do grupo controle quando considerado o índice de assimetria do músculo masseter, apresentando funcionamento muscular mais assimétrico na tarefa de máxima intercuspidação dentária. Conclusão: Os pacientes com trauma de face apresentam alterações significativas em postura, mobilidade, funções orofaciais, amplitude mandibular e na atividade eletromiográfica. O tipo de tratamento médico não influenciou os resultados da funcionalidade muscular no período de até seis meses após a correção da fratura / Purpose: to characterize the oral-motor sytem of adults with facial factures, comparing the performance of individuals submitted to open and closed surgical treatment. Methods: 57 adults divided into three groups: G1 - 19 individuals submitted to open surgery for the correction of at least one of the facial fractures; G2 - 19 individuals submitted to closed surgery for the correction of facial fractures; GC - 19 voluntary healthy individuals, with no alterations of the orofacial myofunctional system. All participants underwent the same assessment: clinical assessment of the orofacial myofunctional system; evaluation of the mandibular range of movements; and surface electromyography (sEMG) of the masticatory muscles. Results: the results indicated that both groups with facial fractures presented significant differences when compared to the control group, in terms of the mobility of the oral-motor organs, mastication and swallowing. However, the groups with facial fractures did not differ in performance. Regarding the measurements obtained for the mandibular movements, both groups with facial fractures presented significant differences when compared to the control group, indicating greater restrictions in mandibular movements. The group submitted to closed surgery presented better range of movements when compared to the group submitted to open surgery, especially when considering the measurement of maximal mandibular opening. When analyzing the results of the sEMG, the group submitted to open surgery presented lower muscle activation when compared to the other two groups. Both groups with facial fractures differed significantly from the control group when considering the index of asymmetry for the masseter muscle, presenting a more asymmetrical muscle function during the task of maximum voluntary teeth clenching. Conclusion: Patients with facial trauma present significant deficits in posture, mobility and function of the oral motor system. The type of medical treatment did not have an influence on the results of muscle function during the first six months after fracture reduction
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Estudo biomecânico ex vivo em coluna tóraco-lombar de cães com técnicas de estabilização utilizando Placa Bloqueada, Clamp Rod Internal Fixation, Pino com Cimento Ósseo e Técnica Segmentar Modificada / Ex vivo biomechanical evaluation of the canine thoracolumbar spines with techniques of stabilization using Locking Plate, Clamp Rod Internal Fixation, Pins with Bone Cement and Modified Segmental InstrumentationFigueiredo, Adriana Valente de 18 October 2013 (has links)
Fraturas e luxações vertebrais decorrente de trauma consistem afecção neurológica frequente na prática clínica veterinária, sendo a coluna tóraco-lombar a mais comumente afetada em cães, e em muitos casos o tratamento cirúrgico é de eleição. Existem diversas técnicas propostas a realizar estabilização vertebral, entretanto, estudos em coluna tóraco-lombar não foram realizados para avaliar as propriedades biomecânicas de cada técnica. Baseado nisso, nossa pesquisa teve como objetivo fazer uma avaliação biomecânica comparando a força e rigidez promovidas por cinco diferentes técnicas de estabilização em coluna toracolombar (Pinos com Cimento Ósseo, Técnica Segmentar Modificada, Placa Bloqueada e Clamp Rod Internal Fixation utilizando parafusos monocorticais e bicorticais) frente às forças de compressão e flexão. Foram utilizadas 34 colunas tóraco-lombares de cães, divididas em cinco grupos. Para realização dos testes biomecânicos, foi utilizada a máquina de ensaios Kratos (modelo KE3000MP) e célula de carga de 100 kg. Para cada corpo de prova, três testes biomecânicos foram realizados, o controle, no segmento íntegro, após desarticulação de T13/L1 e após realização de uma das técnicas de estabilização propostas. Os dados foram exportados para análise estatística para o programa Statistical Package for the Social Sciences (SPSS) versão 18.0. Os resultados permitiram concluir que, apesar de não haver diferença estatística significativa, a Placa Bloqueada foi a técnica que promoveu maior rigidez e estabilidade nas vértebras lesionadas, seguida do CRIF bicortical, técnica Segmentar Modificada e Pinos e Cimento Ósseo. Estatisticamente, a Placa Bloqueada e o CRIF com parafusos bicorticais apresentaram maior rigidez e estabilidade em T13/L1 quando comparados com a técnica CRIF monocortical, que por sua vez, não alcançou rigidez necessária para adequada estabilização das vértebras. / Spinal fractures and luxations resulting from trauma consist frequent disorder in clinical veterinary practice, being thoracolumbar spine the region that is the most commonly affected in canines, thus in many cases surgical treatment is necessary. There are several proposed techniques of implants to perform spinal stabilization; however, few studies of the thoracolumbar spine were carried out to evaluate the biomechanical properties of each technic. Therefore, the objective of the present study is to analyze biomechanical effects comparing the strength and the stiffness promoted by five different technics of stabilization in the thoracolumbar spine (pin with bone cement, modified segmental stabilization, locking plate and clamp rod internal fixation) under compression and bending forces. In the study, thirty four thoracolumbar dog spines were used, dividing the specimens in five groups. In order to perform the biomechanical tests, it was used a Kratos testing machine (model KE3000MP) and loading cell of 100 Kg. Each body of proof was submitted to three biomechanical tests, the control, in the segment intact, after disarticulation of the T13/L1 and after the realization of one of the proposed technics. Data were exported to statistical analyses to the Statistical Package for the Social Sciences (SPSS) version 18.0. The results led to the conclusion that despite there was no statistically significant difference between the techniques, the Locking Plate was the technique that promoted greater rigidity and stability in the injured vertebrae, followed by the Clamp Rod Internal Fixation bicortical, Modified Segmental Instrumentation and Pins with Bone Cement. Statistically, the locking plate and the Clamp Rod Internal Fixation with bicortical pins showed more stiffness and stability in T13/L1 when compared to the Clamp Rod Internal Fixation monocortical, which did not achieved the adequate rigidity for the stabilization of the vertebrae.
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Évolution des propriétés de confinement des roches-couvertures type argilite soumises à des fluides enrichis en CO2 : impact des discontinuités naturelles et artificielles / Confinement properties evolution of the caprocks argillite-type under CO2 enriched-fluids : impact of the natural and artificial discontinuitiesBerthe, Guillaume 20 December 2012 (has links)
Ces travaux de recherche s’inscrivent dans le cadre des études de faisabilité du stockage du dioxyde de carbone en couches géologiques profondes, et portent plus particulièrement sur l’évolution des propriétés de confinement de roches-couvertures de type argilite, soumises à des fluides enrichis en CO2. Pour ce faire, les argilites de Tournemire (Aveyron, France) ont été utilisées comme roches analogues, après avoir identifié leurs possible points de faiblesse vis-à-vis du stockage, à savoir leur minéralogie, la présence de fissures naturelles remplies de calcite et la présence d’interfaces ciment/argilite attendues au niveau des puits d’injection rebouchés. Le montage expérimental de type « diffusion à travers » a été adapté pour permettre d’estimer (i) la possible modification des paramètres de transport diffusif enregistrés, avant et après attaque acide, pour les différents traceurs radioactifs (tritium et chlore-36) et non-radioactifs (deutérium et bromure) utilisés pour caractériser les échantillons d’argilite de Tournemire et de pâte de ciment et (ii) l’évolution des compositions chimiques des solutions contenues dans les réservoirs amont et aval des cellules de diffusion au cours des attaques acides. Enfin, l’analyse des solides a été réalisée pour partie par MEB-EDS, µTomographie-X et DRX. Tout d’abord, pour l’ensemble des échantillons étudiés, les valeurs des paramètres de transport déterminées avant attaque acide (coefficient de diffusion effectif et porosité) sont cohérentes avec celles de la littérature. En outre, il apparaît que tous les matériaux ont fortement réagi aux attaques acides. Ainsi, les argilites ont vu leurs paramètres de diffusion augmenter jusqu’à un facteur deux, notamment pour les traceurs anioniques, et ce, quelque soit la proportion de minéraux carbonatées présents initialement dans les échantillons d’argilite. Les observations post-mortem ont permis l’identification d’une zone de dissolution des minéraux carbonatés en leur au sein, mais dont l’extension (400 µm au maximum) ne peut à elle seule expliquer cette importante dégradation des propriétés de confinement. Seuls des phénomènes non observables à l’échelle d’investigation, tels des effets de digitation au sein du réseau poreux pourraient en être à l’origine. Par ailleurs, les échantillons d’argilites recoupés par des fissures naturelles ont systématiquement développé des courts-circuits hydrauliques, qui s’expliquent par la mise en place d’un processus de chenalisation préférentielle au sein même de la fissure, observé au MEB-EDS et par µTomographie X. De plus, les matériaux cimentaires ont vu leurs propriétés de confinement améliorées, et ce, plus le fluide d’attaque était proche de la neutralité. Ceci est lié à l’apparition d‘une croûte de calcite d’environ 30 µm d’épaisseur, situé à l’avant d’une zone de dissolution, dont l’épaisseur est proportionnelle à la quantité d’acide en solution. Cette croûte imperméable, obstruant la porosité, serait responsable de la diminution des paramètres de diffusion, observée à l’échelle de l’échantillon, ainsi que le reproduisent les simulations numériques. Enfin, les interfaces ciment/argilites n’ont pas révélé de changement de leurs propriétés de confinement à l’échelle globale, la dégradation des argilites étant compensé par l’aggradation du ciment via la formation de cette croûte de calcite. / This research is part of the studies of feasibility of CO2 storage in deep geological strata, focusing more particularly on the evolution of the confinement properties of cap-rocks type argillite subjected to CO2 enriched fluids. The argillite of Tournemire (Aveyron, France) were used as analog rocks, having identified what their weak points could be face to storage, namely their mineralogy, natural fractures filled with calcite and the presence of interfaces cement / argillite expected in filled injection wells. The "through diffusion" experimental setup has been adapted to estimate (i) the possible modification of diffusive transport parameters recorded before and after acid attack for different radioactive tracers (tritium and chlorine-36) and non-radioactive tracers (deuterium and bromide) used to characterize samples of argillite of Tournemire and cement paste and (ii) the evolution of the chemical compositions of the solutions in the upstream and downstream reservoirs of diffusion cells during acid attacks. Finally, the analysis of solids was carried out in part by SEM-EDS, XRD and X-μTomographie. Firstly, for all the samples studied, the values of the transport parameters determined before acid attack (effective diffusion coefficient and porosity) are consistent with those of the literature. In addition, it appears that all materials have reacted strongly to acid attacks. Thus, argillites saw their diffusion parameters increase up to a factor of two, especially for anionic tracers, and, whatever the proportion of carbonate minerals initially present in samples of argillite. The post-mortem observations have led to the identification of a zone of dissolution of carbonate minerals in them, but whose extension (400 microns or less) can not alone explain the significant degradation of the containment properties. Only unobservable phenomena during investigation scale, such as wormhole effects in porous network could be the cause. In addition, the samples of argillite intruded by natural fractures have systematically developed hydraulic short circuits, which can be explained by the introduction of a process of preferential channeling within the fracture observed by SEM-EDS and X. μTomographie In addition, the more close to neutral was the fluid attack the more cementitious materials saw their confinement properties improved. This is related to the appearance of a crust of calcite about 30 microns thick on the front of a dissolution zone, the thickness of which is proportional to the amount of acid in solution. This waterproof crust, clogging the pores, would be responsible for the decrease in diffusion parameters observed across the sample, and as numerical simulations reproduce it. Finally, the interface cement / claystone showed no change in their confinement properties on a global scale, the degradation of clays being offset by aggradation cement via the formation of the crust of calcite.
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Estudo comparativo entre as osteossínteses de tornozelo com implantes convencionais e bioabsorvíveis / Comparative study of osteosynthesis of ankle with conventional and bioabsorbable implantsGaiarsa, Guilherme Pelosini 06 March 2013 (has links)
O padrão ouro no tratamento cirúrgico das fraturas de tornozelo são as sínteses metálicas, sejam de titânio ou aço. Os implantes bioabsorvíveis foram desenvolvidos para evitar o efeito do stress shielding, ou escudo de carga, e a retirada de material de síntese. O uso de materiais absorvíveis é bem documentado, e com bons resultados em grande número de fraturas craniofaciais. O objetivo deste estudo foi comparar os resultados funcionais de fraturas de tornozelo tratadas com placas metálicas e absorvíveis. Os pacientes foram randomizados e seguidos de forma prospectiva em dois grupos, metálico e absorvível. No período pós operatório imediato os pacientes foram imobilizados com tala gessada por uma semana, substituída por órtese removível por mais 4 semanas. Carga parcial foi autorizada com 3 semanas, e carga total com 6 semanas. Dezenove pacientes foram seguidos por nove meses, e avaliados radiográfica e funcionalmente aos 6 e 9 meses. Todos consolidaram entre 8 e 12 semanas. A recuperação funcional foi similar nos dois grupos. Aos 6 meses, três pacientes no grupo metálico queixaram-se de problemas locais, e tiveram seus implantes removidos. Um paciente do grupo absorvível teve uma deiscência da sutura, tratado com boa evolução. Aos 9 meses foi aplicado o escore da AOFAS para todos os pacientes. Os resultados funcionais foram semelhantes nos dois grupos, após a retirada de implante de três pacientes no grupo metálico. Os implantes absorvíveis permitiram resultados clínicos e funcionais semelhantes aos metálicos em fraturas de tornozelo / The current gold standard fixation system for surgical ankle fractures are the metallic implants, steel or titanium made. Resorbable implants have been developed to avoid stress shielding and a new surgery for implant removal, common with metal implants. Use of resorbable implants is well documented in the literature for a range of craniofacial fractures, with good results. The purpose of this study was to compare the outcome of ankle fractures using biodegradable and metal plates. Patients were randomly and prospectively treated with resorbable or metal fixation system. Post-operatively, the ankle was immobilized with a plaster cast for 1 week, removable cast for other 4 weeks. Half and full weight bearing were allowed at weeks 3 and 6. nineteen patients were followed for 9 months. Functional recovery was similar in both groups at 6 and 9 months, three patients in metal group complained implant-related problems, and had their implants removed, and one in resorbable had an acute dehiscence, solved with surgical debridement and closure. At 6 and 9 months, the AOFAS score was applied for all patients. The functional results were similar in both groups. Implant removal was necessary in three patients from the metallic group. The resorbable plate provided qualitatively similar fracture healing results as the metal plate
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Impact de l’hétérogénéité sur la recharge naturelle et artificielle des aquifères cristallins altérés et fracturés : application aux sites de Maheshwaram et Choutuppal (Inde du Sud) / Impact of heterogeneity on natural and managed aquiferrecharge in weathered fractured crystalline rock aquifersNicolas, Madeleine 07 May 2019 (has links)
Les facteurs qui régissent l'intensité et la répartition de la recharge naturelle et artificielle dans les aquifères cristallins altérés et fracturés sont mal connus. Ce sont cependant les caractéristiques déterminantes de ce type de roche—ces roches sont très hétérogènes—qui rendent difficile l’estimation des flux dans ces milieux ainsi que des propriétés hydrauliques qui les contrôlent. La première partie de ce manuscrit fournit un état des connaissances sur la recharge des eaux souterraines et ses méthodes d’estimation, permettant de comprendre les défis scientifiques et sociétaux abordés dans cette thèse. La deuxième partie présente les travaux numériques et expérimentaux menés pour approfondir notre compréhension de la dynamique des flux d’eaux souterraines dans ces milieux hétérogènes à plusieurs échelles. Le premier axe de recherche porte sur les processus de recharge naturelle à l’échelle du bassin versant. La recharge diffuse a été modélisée avec un modèle physique simple d’infiltration et comparée à des estimations préalables de recharge totale. Nos résultats illustrent la forte dépendance de la recharge aux précipitations et à l’irrigation, et l’importance de la recharge focalisée. Les facteurs responsables de la distribution spatiale de la recharge sont aussi étudiés. Le deuxième axe est basé sur le suivi de la mise en eau d’un bassin de recharge artificielle dans un site hautement monitoré et bien équipé. Ces observations ont été interprétées avec des modèles analytiques et numériques. Ces modèles ont mis en évidence l’existence de flux préférentiels horizontaux, mais aussi d’une compartimentation latérale qui entrave la propagation des intrants de recharge. / The factors governing the intensity and distribution of natural and artificial recharge in weathered and fractured crystalline aquifers are poorly understood. However, it is the defining characteristics of this type of rock—these rocks are very heterogeneous—that make the estimation of fluxes and the hydraulic properties controlling them difficult. The first of its two parts provides the theoretical framework on groundwater recharge processes and its estimation methods for comprehending the scientific and societal challenges discussed in this thesis. The second part presents the numerical and experimental work carried out to deepen our understanding of the dynamics of groundwater flows in these heterogeneous underground environments at several scales. The first line of research focuses on natural recharge processes at the watershed scale. Diffuse recharge was modeled with a simple physical infiltration model and compared to previous estimates of total recharge. Our results highlight the strong dependence of recharge on rainfall and irrigation, and the importance of focused recharge. The factors responsible for the spatial distribution of recharge are also studied. The second axis is based on the monitoring of the filling of an artificial recharge basin at a highly monitored and well-equipped site. These observations were interpreted with analytical and numerical models to improve our knowledge of flow dynamics in fractured crystalline rocks at the medium scale. These models illustrated the existence of preferential horizontal flows, but also of a lateral compartmentalization that hinders the propagation of recharge inputs.
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Physical properties of a thermally cracked andesite and fluid-injection induced rupture at laboratory scale / Les proprietes physiques des andesites fractures thermiquement et les ruptures induites par injection de fluides a l echelle du laboratoireLi, Zhi 22 March 2019 (has links)
Comprendre et connaitre les propriétés physiques et le comportement mécanique de l'andésite est important pour des applications industrielles comme la géothermie ou le stockage de CO2 mais aussi pour comprendre différents processus naturels. Tout d'abord, les effets de la fissuration thermique sur les propriétés physiques et les processus de rupture de l'andésite ont été étudiés via des expériences triaxiales à taux de déformation constant et à température ambiante. Deuxièmement, nous avons effectué des recherches sur les effets de l'altération sur le comportement physique et la minéralogie. Enfin, une série d'expériences a été réalisée afin d'étudier l'effet de la variation de la pression du fluide i) sur le comportement mécanique des échantillons d'andésite et ii) sur les activités d'émissions acoustiques. / The physical properties and mechanical behavior of andesite are of interest in the context of geothermal reservoir, CO2 sequestration and for several natural processes. The effects of thermal crack damage on the physical properties and rupture processes of andesite were investigated under triaxial deformation at room temperature. Secondly we did research on the effect of alteration on physical behavior and mineralogy. At last a series of experiments were performed in order to investigate the effect of fluid pressure variation i) on the mechanical behavior of andesite samples and ii) on acoustic emissions activities
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Etude des processus d'instabilités des versants rocheux par prospection géophysique<br />- Apport du radar géologique -Jeannin, Mathieu 28 September 2005 (has links) (PDF)
L'évaluation de la stabilité des falaises est complexe, du fait de l'incertitude des mécanismes de rupture et de la méconnaissance de l'état de fracturation interne du massif. Les méthodes géophysiques permettent d'obtenir de l'information sur la structure interne du massif. Le radar géologique a montré son efficacité pour détecter et caractériser les fractures. Plusieurs profils radar (réflexion, transmission, CMP) sont testés sur deux falaises verticales calcaires proches de Grenoble. La combinaison de profils verticaux et horizontaux permet de mieux contraindre la géométrie 3D du réseau de fractures. Les analyses de vitesses radar, déduites des acquisitions CMP, permettent de caractériser directement les larges fractures ouverture en profondeur. La tomographie radar fournit une image 2D de l'intérieur du massif, mais avec une trop faible résolution. Dans une gamme de fréquences donnée, la détection de fractures par le radar va dépendre de l'ouverture et du remplissage, qui contrôlent le coefficient de réflexion. Une stratégie de caractérisation des fractures est proposée en utilisant la sensibilité fréquentielle de la réflectivité. L'inversion des coefficients de réflexion radar, basée sur un algorithme de voisinage, permet de retrouver les paramètres caractéristiques des fractures modélisées. La méthode du rapport spectral entre un signal réfléchi (mesuré) et un signal de référence (connu), permet de calculer facilement le coefficient de réflexion. Une étude numérique 2D (FDTD) est menée pour le choix du signal de référence. L'inversion des coefficients de réflexion radar synthétiques est testée pour une configuration de fracture ouverte rencontrée sur le terrain.
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Etudes liées à la vitrification sans fracture de solutions cryoprotectricesOdagescu, Valentina Maria 07 July 2005 (has links) (PDF)
La cryopréservation par vitrification est une technique qui devrait permettre de rallonger considérablement les durées de conservation des greffons en abaissant leur température de stockage jusqu'à – 196°C. Elle nécessite l'utilisation de solutions cryoprotectrices (contenant des antigels biocompatibles) pour empêcher la cristallisation de glace dans les tissus, ainsi que des vitesses de variation de la température relativement rapides. La calorimétrie différentielle à balayage permet de déterminer les vitesses requises pour la vitrification des solutions cryoprotectrices. L'exemple de l'éthylène glycol est présenté, complétant les informations connues sur ce cryoprotecteur dans la plage des concentrations concernant la vitrification. Au niveau de la procédure de vitrification, la méthode du recuit a permis d'éviter l'apparition de fractures dans des volumes importants de solution cryoprotectrice. Le cas particulier de la solution VM3 (21st Century Medicine) est détaillé. Il permet de montrer que la stabilité de l'état amorphe ainsi que la quantité de glace cristallisée au réchauffement sont influencées par la température et la durée du recuit. Une analyse sur l'influence du type et de la forme du container porte-échantillon par rapport à la qualité du verre fabriqué a été commencée en parallèle, mais les limites du dispositif cryogénique utilisé nous ont poussé à développer un nouveau cryostat automatisé, permettant de faire des études systématiques dans des conditions reproductibles. Ce cryostat, entièrement conçu et construit au CRTBT, représente le prototype de ce que nous souhaitons proposer à des médecins pour les aider dans leur étude clinique de la cryopreservation des systèmes biologiques. Sa précision de mesure et sa facilité d'utilisation nous a pour le moment permis de mettre en évidence différents événements ayant lieu pendant la vitrification et le réchauffement de nos échantillons.
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The effect of rework on brittle fractures in lead free solder joints : The growth of intermetallic compounds during rework and its effectsDornerus, Elin January 2009 (has links)
<p>Saab Microwave Systems, SMW is a supplier of radar systems. The circuit boards that are operating in their radars have components which solder joints contains lead. However, the EU directive RoHs and WEEE are causing SMW to prepare for a transition to lead free solder joints. The objective of this thesis is to gain deeper knowledge of lead free solder joints.</p><p>Brittle fractures in solder joints is a type of failure that might increase in a transition to lead free solder joints. The brittle fractures are induced by the creation of the intermetallic phases which are formed during soldering. The amount and composition of the intermetallics affects the mechanical strength of the joint. An intermetallic layer is thickened during heat exposure as during soldering, thermal aging and rework.</p><p>The focus of this thesis was to investigate how rework affect the brittleness of the lead free solder joint and thereby how the intermetallic layers change depending on chemical composition, design and reflow cycles. Two types of components and two types of solder materials (SnPb and SAC305) were studied.</p><p>To study the mechanical properties of the joint a shear testing device was used. This is a way of measuring the reliability of the joint when subjected to mechanical shock. The intermetallic layers were examined in a Scanning Electron Microscope and the fracture surfaces were studied in a optical microscope, a scanning electron microscope and a stereomicroscope. The heat spread over the board where examined by soldering thermocouples to the board and plotting the values of time and temperature.</p><p>The results showed that the rework process did not have any significant impact of the intermetallic growth. The adjecent and distant components were not damaged during rework. A lead free rework process can therefor be preformed successfully at SMW. The intermetallic layers formed at the interface between the a lead free solder and a nickel finish grew faster than an intermetallic layer formed between a leaded solder and a nickel finish. The presence of nickel could therefore have a more negative effect on the intermetallic growth rate for the lead free material compared to the leaded.</p>
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Caractérisation géotechnique des massifs rocheux par étude structurale et essais in situ : applications aux sites de barragesGiraud, Andre 26 September 1986 (has links) (PDF)
Le comportement géotechnique des massifs rocheux est principalement régi par leurs discontinuités. Celles-ci ont pour cause les déviateurs de contrainte et de déformation appliqués au massif tout au long de son histoire géologique. On en conclut que les caractéristiques mécaniques et hydrauliques actuelles d'un massif dépendent à la fois de ses particularités structurales acquises et éventuellement de contraintes s'exerçant de nos jours, notamment par suite du mouvement des plaques lithosphériques. L'appréciation de la qualité d'un site doit s'efforcer de combiner l'analyse structurale, les mesures in situ et, si possible, les données acquises par la sismologie. Une telle démarche permet de généraliser les résultats de reconnaissances par nature ponctuelles et de mieux comprendre certaines anisotropies mécaniques et hydrauliques. Des études de sites de fondation de barrages, en terrains cristallins et cristallophylliens, effectuées en Arabie Séoudite et dans les Pyrénées-Orientales illustrent la démarche méthodologique qui vient d'être proposée.
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