Ce travail s’inscrit dans le développement de formulations performantes et processables pour les liners de réservoirs de stockage hyperbare. Une large gamme de formulations à base polyamide et polyépoxyde a ainsi été synthétisée en conditions contrôlées, représentatives du procédé de rotomoulage. Les systèmes polyamide ont été modifiés par copolymérisation statistique et les polyépoxydes par une phase dispersée micro- ou nano-structurée avec des thermoplastiques de haute Tg ou des copolymères blocs. Les propriétés morphologiques, thermiques, mécaniques et barrière de chaque formulation ont été caractérisées et confrontées au cahier des charges du matériau. En parallèle, l’influence des conditions opératoires et de la formulation sur les rhéocinétiques de polymérisation, de cristallisation, de gélification et/ou de séparation de phase a ainsi été établie. L’ensemble de ces résultats a été mis à profit afin d’identifier des relations structures – propriétés – processabilité en vue de l’application. Afin de valider le potentiel des formulations retenues, ces dernières ont été rotomoulées en conditions opératoires variables avec un suivi in situ de l’écoulement et ex situ de la viscosité. Ce travail a permis d’établir les fenêtres de processabilité de chaque formulation et de comprendre l’origine des défauts d’écoulement. / The aim of this present study is to develop efficient and processable formulations for the liners of high pressure storage tank. A wide range of formulations based on polyamide and polyepoxide has been synthesized under controlled conditions representative of the rotomolding process. The polyamide system has been modified by copolymerization and the polyepoxyde system by a micro- or nano-structured dispersed phase with high Tg thermoplastics or block copolymers. The morphological, thermal, mechanical and barrier properties of each formulation were characterized and compared to the specifications of the material. In parallel, the influence of operating conditions and formulation on the rheokinetics of polymerization, crystallization, gelation and / or phase separation has been established. All of these results have been exploited to identify structure - property - processability relationships for the application. To validate the potential of selected formulations, they were rotationally molded in variable operating conditions with flow monitoring and rheological measure. This work has established the processing windows of each formulation and has allowed an understanding of the origin of flow defects.

Le développement de structures de plus en plus légères et présentant des rapports performances/coût toujours plus élevés est un enjeu permanent dans le domaine des transports. Les matériaux polymères présentent des caractéristiques particulièrement bien adaptées à ces besoins. Ce travail de thèse repose sur le développement d’un matériau polymère destiné à être utilisé en tant que liner de réservoir de stockage d’oxygène liquide (LOX). L’objectif est de démontrer une réduction des masses de l’ordre de 20 à 30%, en comparaison avec des structures métalliques. Pour les besoins de l’application, le matériau à développer se doit de présenter une bonne compatibilité au LOX, une faible perméabilité aux gaz, des propriétés mécaniques suffisamment élevées à basse température ainsi qu’une bonne aptitude à la mise en forme par rotomoulage. La première partie de ces travaux a porté sur la compatibilité au LOX des polymères. En tenant compte des théories proposées dans la littérature, des nanocomposites à matrice polyamide 6 (PA6) ont été élaborés et caractérisés afin d’atteindre les performances recherchées. L’influence de différents paramètres supposés régir la tenue à l’oxygène liquide des matériaux polymères a ensuite été déterminée. Les nanocomposites obtenus présentent globalement une bonne compatibilité avec le LOX. Cette étude a également permis de mettre en évidence que les résultats sont fortement dépendants des paramètres liés à l’échantillonnage. Dans un second temps, la processabilité par rotomoulage de ces nanocomposites PA6 a été évaluée. Les propriétés rhéologiques et de stabilité thermique ont notamment été étudiées. Quelques essais de rotomoulage sur les systèmes les plus pertinents ont également été réalisés et ont démontré des résultats encourageants. Dans une dernière partie, les propriétés barrière aux gaz de ces systèmes PA6 ont été étudiées. Les perméabilités mesurées ont été interprétées en tenant compte de la morphologie des mélanges. En particulier, cette étude montre que les nanocomposites à base de PA6 et de graphite lamellaire présentent des performances adaptées pour l’application en raison de l’effet de tortuosité induit par la charge. Les propriétés mécaniques en traction uniaxiale des systèmes élaborés ont finalement été déterminées et confrontées aux spécifications requises. Les résultats obtenus montrent que les caractéristiques mécaniques sont tout à fait adaptées pour une utilisation en tant que liner de réservoir de stockage d’oxygène liquide. / In the field of transport, the development of lighter, cheaper and more efficient structures is a recurrent challenge. Polymer materials are good candidates for these applications due to their characteristics quite suitable for requirements. This Phd work aims at developing a thermoplastic material which will be used as an internal liner of a liquid oxygen (LOX) storage tank. The objective is to demonstrate a 20 % to 30 % weight saving, compared to metallic structures. To be used in this kind of application, the thermoplastic material must be LOX compatible, processable by rotational moulding and display a low gas permeability as well as good mechanical properties at low temperatures. In a first part, LOX compatibility of polymers was studied. Taking into account theories proposed in the literature, polyamide 6 (PA6) nanocomposites based on LCP, fluoride and graphite fillers were processed and characterized in order to reach desired properties. The influence of several parameters having an impact on LOX behaviour of polymers was then investigated. The nanocomposites show overall good compatibility with liquid oxygen. This study also demonstrates that LOX sensitivity largely depends on the preparation of samples. The processability of nanocomposites by rotational moulding has then been investigated. Rheological properties and thermal stability have especially been studied. Some rotational moulding trials were carried out on the most relevant systems and demonstrate promising results. Finally, the gas transport properties of PA6 nanocomposites were studied. Measured gas permeability was discussed as a function of the morphology of blends. In particular, this study shows that PA6 nanocomposites filled with lamellar graphite present convenient performances which are due to the tortuosity effect induced by the filler. Mechanical properties of filled systems were finally determined and compared with set requirements. The results show that mechanical characteristics are quite relevant for use as internal liner of LOX storage tank.

No description available.

Das Formdrücken findet seine industrielle Anwendung in der Herstellung rotationssymmetrischer Hohlbauteile für kleine und mittlere Losgrößen. Diese Bauteile werden häufig in einem weiteren Verfahrensschritt als Vorform für die Herstellung profilierter Hohlkörper genutzt. Verfahrensbedingt tritt bereits bei der Vorformherstellung eine ungewollte Blechdickenabnahme auf. Um diese Blechdickenabnahme zu minimieren, wurde anhand numerischer Methoden das Verfahren des Rotationsschwenkbiegens an der Professur Virtuelle Fertigungstechnik der TU Chemnitz entwickelt. Das Prinzip dieses inkrementellen Umformprozesses basiert auf einer Verfahrenskombination des konventionellen Drückens und des Schwenkbiegens, mit dem Ziel der faltenfreien Herstellung von Hohlbauteilen bei gleichzeitiger minimaler Blechausdünnung. Die als Halbzeug verwendete Ronde wird zu Beginn des Prozesses auf eine formgebende Matrize gespannt und in Rotation versetzt. Durch die Schwenkbewegung eines zylindrischen Umformwerkzeuges wird das ebene Blech an die Kontur der Matrize angelegt, wobei keine Relativbewegung zwischen Blech und Werkzeug stattfindet. Demzufolge entstehen minimale Zugspannungen in der Blechebene und die Blechausdünnung wird deutlich verringert. Durch die Durchmesserreduzierung bilden sich jedoch ebenso tangentiale Druckspannungen aus, welche zu einer ungewollten Faltenbildung führen können. Im Rahmen des Vortrages werden anhand von FEM-Simulationen Möglichkeiten vorgestellt, um diese Druckspannungen zu reduzieren oder gezielt zur Vorformherstellung für profilierte Hohlbauteile zu nutzen.

In addition to previous publications, the paper presents the analytical solution of a special boundary value problem which arises in the context of elasticity theory for an extended constitutive law and a non-conservative symmetric ansatz. Besides deriving the general analytical solution, a specific form for linear boundary conditions is given for user convenience.

<p> A method for tlie dynamic analysis· of planar coupled shear walls subjected to ground motions is developed herein. The method is capable of application to nonuniform coupled shear walls resting on flexible foundations. The possibility-of development of yield hinges at the ends of the connecting beams is included in the analysis . Also P-& Effect is incorporated in the stiffness of the structure. </p> <p> The method is based on the transfer matrix technique in combination with the continuum method. A step-by-step integration approach is used in solving the equation of motion. The response to a number of earthquake records are obtained. The effect of the rotational ductility factor of connecting beams is studied. </p> / Thesis / Master of Engineering (MEngr)

The dissertation research is devoted the impact of functional training with suspension and rotation of equipment for the weight correction of the visitors are middle aged (45-50 years) in the fitness club. Got results from the use of this equipment in order the weight loss people seeking to lose weight. / Диссертационное исследование посвящено рассмотрению влияния функциональной тренировки с помощью подвесного и ротационного оборудования на коррекцию веса у посетителей среднего возраста (45-50 лет) в фитнес клубе. Получены результаты использования этого оборудования в целях коррекции веса у людей, стремящихся к похудению.

[pt] Na indústria de óleo e gás, a paralisação da produção e do transporte nas linhas de fluxo causadas pela deposição de compostos orgânicos e inorgânicos rendem enormes perdas financeiras e preocupações ambientais. Um dos fatores mais comuns e críticos na deposição orgânica está relacionado com a formação de hidratos de gás, que são sólidos cristalinos de base aquosa, fisicamente semelhantes ao gelo, formados em condições de alta pressão e baixas temperaturas. Devido a esses fatos preocupantes, fenômenos relacionados aos hidratos, como formação, dissociação e formas de mitigação, vêm sendo estudados há anos por pesquisadores. Neste trabalho foram realizados experimentos para analisar a formação de hidrato de gás de etano em emulsões água em óleo, através de uma análise reológica baseada na variação de pressão, taxa de cisalhamento e fração de volume de água, e usando as geometrias vane e de cilindros concêntricos. Testes de varredura de tempo de alta pressão foram realizados, e os resultados foram apresentados através de curvas de viscosidade e pressão. A quantidade de água convertida em hidrato também foi estimada através da equação de estado e relacionada com a viscosidade das pastas de hidratos formadas. Os resultados obtidos mostram que o período de indução foi reduzido pelo aumento do subresfriamento, corte de água e taxa de cisalhamento. Quanto maior a fração de volume de água, maior o nível atingido pela viscosidade quando identificada a formação de hidratos. A viscosidade relativa, após a formação do hidrato, foi estudada. Esse conhecimento proporcionou uma compreensão mais efetiva de algumas diferenças observadas entre as duas geometrias. E para complementar o estudo, foram realizadas rampas de taxa de cisalhamento mostrando semelhanças entre os três resultados com cilindros concêntricos, mas diferenças entre os resultados com geometria vane. Ambas as geometrias, vane e cilindros concêntricos, foram consideradas adequadas para estudar a formação de hidratos e resultados qualitativos semelhantes foram obtidos. / [en] In the oil and gas industry, the stoppage of the production and transportation flowlines caused by the deposition of organic and inorganic compounds yields huge financial losses and environmental concerns. One of the most common and critical inorganic deposition is related with gas hydrates, which are crystalline water-based solids, physically similar to ice, formed in conditions of high pressure and low temperatures. Due to the worrying facts, phenomena related to hydrates, as formation, dissociation, and forms to its mitigation have been studied for years by researchers. In this work, experiments were carried out to analyze ethane gas hydrate formation in water-in-model oil emulsions, through a rheological analysis based on the variation of pressure, shear rate and water volume fraction, and using the vane and concentric cylinder geometries. High pressure time sweep tests were performed, and the results were presented through viscosity and pressure curves. The amount of water converted to hydrate was also estimated through the equation of state and related to the viscosity of the hydrate slurries formed. The results obtained showed that the induction period was reduced by increasing the subcooling, water cut, and shear rate. The higher the water volume fraction, the higher the level reached by viscosity when hydrate formation is identified. The relative viscosity after hydrate formation was studied. This knowledge provided a more effective understanding of some differences observed between the two geometries. And to complement the study, shear rate ramps were performed showing similarities between results with concentric cylinders but differences with vane. Both geometries, vane and concentric cylinders, seem to be adequate to study hydrate formation and similar qualitative results were obtained.

No description available.

No description available.