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Podnos, Eugene Grigorievich. "Application of fictitious domain method to analysis of composite materials /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Jouve, Christophe. "Etude de matériaux composites dans des structures : métal-composite-métal, métal-composite-semiconducteur : application aux capteurs en phase gazeuse." Lyon 1, 1993. http://www.theses.fr/1993LYO10232.
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Les solides organiques offrent des perspectives prometteuses de materiaux pour la realisation de dispositifs electroniques. La sensibilite de ces materiaux a un environnement physico-chimique conduit a les utiliser pour l'integration de capteurs intelligents. Le travail que nous presentons concerne des structures minces de polyethylene (ldpe) dans lequel sont inclus des sels de complexes a transfert de charges (ctc). La methode d'elaboration permet de realiser des films conducteurs de quelques microns d'epaisseur dans lesquels la cristallisation des sels depend des conditions d'elaboration. Une part importante de cette etude est consacree a la correlation entre la composition des films et leurs proprietes de conduction electrique. Nous cherchons aussi, en plus de l'optimisation du procede d'elaboration, a contribuer a une meilleure comprehension des mecanismes de conduction electrique qui restent a eclaircir en ce qui concerne ces materiaux. Les mesures en continu mettent en evidence des phenomenes d'injection au-dela d'une zone ohmique a 10#3v/cm. Les mesures en alternatif (jusqu'a 1 mhz) revelent, suivant la concentration en sels de ttf-tcnq, des variations plus ou moins importantes de la conductivite autour de 100 khz. Des hypotheses concernant le comportement en frequence sont proposees. Ces resultats permettent de determiner differents parametres propres a ces structures et qui caracterisent les modes de conduction observes. Dans l'objectif de l'exploitation de ces films comme detecteur d'entite gazeuse, des essais d'absorption ont ete realises avec de l'oxygene, du dioxide d'azote, du dioxyde de carbone ainsi que sous atmosphere humide. Les premiers resultats obtenus par absorption sont tres encourageants pour la mise au point et le developpement de dispositifs capteurs utilisant ces materiaux
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Wong, Yi Wai. "Fabrication of grid-domed textile composite and its application in safety helmets /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20WONG.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 136-139). Also available in electronic version. Access restricted to campus users.
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Wang, Xufeng Materials Science & Engineering Faculty of Science UNSW. "Application of single-part adhesives as healing agent in self-healing composites." Awarded by:University of New South Wales. Materials Science and Engineering, 2007. http://handle.unsw.edu.au/1959.4/32233.
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The aim of this study was to develop a new single-part healing system for self-healing composites. The self-healing approach to composite repair has been developed in the last two decades and means that a damaged area can be repaired by material already housed within the structure. The background and development of self-healing has been reviewed. The two main self-healing mechanisms are discussed. To date only two part self healing systems have been examined. These require diffusion of the separate constituents to a single location in order to effect cure and restore strength. Single part adhesives do not have this disadvantage and are therefore very attractive. Several candidate single-part adhesive or resin systems were considered and discussed according to the critical requirements of a self-healing system. A series of experiments was undertaken to evaluate the possibility of candidate adhesive systems being effective for self-healing by focusing on the determination of storage stability and bonding efficiency. The results of storage stability testing showed that the stability of cyanoacrylate and polyurethane adhesives was poor. However silane and polystyrene cements showed good storage stability. Very low bonding efficiency was achieved with polystyrene cement but a 22% strength recovery was obtained with the silane 3-[tris(trimethylsiloxy)silyl]-propylamine. Suggestions for further research into single-part healing systems are also given.
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Qin, Xiaowen. "Modeling Study of Pyrolysis of Composite Materials : Application to Wood and Carbon/Epoxy Composite." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0006.
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Les matériaux composites prennent une place importante dans les applications industrielles ou plus largement dans notre vie courante. Les composites synthétiques substituent les matériaux métalliques en raison du gain de poids pour des propriétés mécaniques identiques. Ce type de matériaux est largement répandu dans les domaines du transport et du stockage de l’énergie. Les composites naturels (bois) sont également très utilisés notamment dans le domaine de l’habitat. L’inconvénient de ces matériaux réside dans leur difficulté à maintenir leurs caractéristiques mécaniques en cas d’incendie ; l’étude de leur tenue au feu est donc un enjeu majeur. Ce travail de thèse vise à développer un modèle numérique de décomposition d’un matériau composite soumis à un flux de chaleur. La simulation de différents cas d’attaque thermique permet d’étudier les interactions entre les processus de transferts de masses, de chaleur et de réactions chimiques au sein du solide. Le modèle développé, 3D décrit les transports au sein des pores du matériau à l’échelle de Darcy. Le transfert de chaleur par conduction est écrit sous forme tensoriel permettant de définir des conductivités dans les 3 directions de l’espace. Pour les 2 types de matériaux, un schéma réactionnel multi-étapes est défini afin de décrire le processus de pyrolyse. Les essais en cône calorimètre qui ont servi à développer le modèle ont été réalisées sous atmosphère inertes (N2) ce qui permet « d’éliminer » la présence de la flamme à la surface du matériau ainsi que les réactions hétérogènes pouvant se produire en présence d’oxygène. Les conditions aux limites définis sont donc plus simples et mieux maitrisées car le caractère instationnaire de la flamme n’est pas pris en compte. Les schémas réactionnels se composent donc uniquement des réactions de pyrolyse excluant ainsi toutes réactions hétérogènes. Les gaz de pyrolyse sont assimilés à un gaz inerte. Les réactions intra-pores sont donc négligées et l’hypothèse de l’équilibre thermique locale entre les phases solides et le gaz environnant est assumée. La construction du modèle décomposition thermique des 2 types de matériaux suit une démarche de séparation des échelles. Les différents processus de transport de chaleur, de masses et de réactions chimiques sont étudiés séparément afin de s’affranchir des interactions et de valider séparément les modèles. Le modèle global est ensuite reconstruit afin de tenir compte de ces interactions. La dégradation thermique est d’abord étudiée à une échelle « 0D » afin de développer les schémas réactionnels. L’Analyse Thermogravimétrique est alors utilisée à cette étape ou des expériences sont conduites à différentes vitesses de chauffage sous atmosphère inerte. Les phénomènes de transports au sein de la particule solide peuvent être négligés, la température de la particule est homogène et sa dynamique est connue. A cette étape, seul le processus de pyrolyse est mis en jeu. Les différentes familles de réactions sont identifiées et décrites au sein du modèle par des réactions apparentes de type Arrhenius. Les constantes cinétiques sont calculées par des méthodes mathématiques inverses. L’influence de la vitesse de chauffage sur le processus de pyrolyse est analysée. Une simulation 2D est réalisée à 2 vitesses de chauffages afin d’analyser l’évolution des gradients thermiques et de pression au sein de la particule. Les phénomènes de transports de chaleur et de masses sont pris en compte à l’échelle du matériau et étudiés par des expériences réalisées en cône calorimètre. A cette échelle, les phénomènes de transports de masses et de chaleur sont calculés. Des simulations sont réalisées pour 2 flux de chaleurs. Les interactions entre les processus de transport de masses, de chaleur et de pyrolyse sont étudiées en analysant les échelles locales de temps et de longueurs afin d’identifier quels sont les phénomènes limitant sur le processus global de décomposition thermiqueComposite materials occupy a critical position in industrial applications or more broadly in our daily life. Synthetic composites substitute metallic materials due to their lightweight properties to achieve identical mechanical performance. They are widely used in the fields of energy transportation and storage. Natural composites (wood) are also widely used, especially in construction industry. The disadvantage of these materials involves the disability in maintaining their mechanical characteristics in a fire scenario, and the study of their fire resistance is therefore a major issue. This thesis aims to develop a mathematical model of thermal decomposition of composite materials subjected to different heating conditions. The simulations of different cases of thermal decomposition make it possible to study the interactions among the processes of heat and mass transfer as well as chemical reactions within the solid. The developed 3D model describes the gas transport within the pores of materials at the Darcy scale. Thermal conductivity is formulated in a tensor form allowing the definition of heat transfer in three directions of the domain. For the two types of materials, a multi-step reaction scheme is defined to describe the pyrolysis process. The cone calorimeter tests used to validate the model were carried out under an inert atmosphere (Nitrogen) which makes it possible to eliminate the presence of flame on the material surface as well as the heterogeneous reactions which can occur in the presence of oxygen. Therefore, the defined boundary conditions are quite simple and well-controlled to characterize without considering the unsteady flame. Pyrolysis gasses are assembled into inert gas, therefore, the gas reactions in the pore are neglected and the local thermal equilibrium between the solid and gas phase is assumed. The implementation of this pyrolysis model follows a scale separation process with two types of materials. The different heat and mass transfer processes, as well as chemical reactions, are studied separately to avoid the interactions, then the model is reconstructed to take these interactions into account. The pyrolysis behavior is firstly studied at a "0D" scale to develop the part of chemical reactions. The thermogravimetric analysis (TGA) is used at this scale and related experiments are conducted at different heating rates under an inert atmosphere. At this scale, only the chemical reactions are involved with known kinetics, and the heat and mass transport within the solid can be neglected with homogeneous temperature distribution. The different chemical reactions are described with the Arrhenius-type equation. The kinetic parameters are calculated by the inverse modeling method. The influence of the heating rate on the pyrolysis process is analyzed and 2D simulations are conducted at two heating rates to analyze the evolution of thermal and pressure gradients within the solid. The phenomena of heat and mass transport are considered and studied by bench-scale experiments which are conducted in the cone calorimeter. The corresponding simulations are implemented under two heat flux. The interactions among the heat and mass transport as well as chemical reaction processes are studied by analyzing the local time and length scales to identify what are the dominant phenomena through the whole pyrolysis process
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Lu, Yan. "Polypyrrole-containing Composite Particles: Preparation, Characterization and Application." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1109235925474-80822.
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This research is focused on preparation of polypyrrole (PPy) composite particles by using socalled template oxidative polymerization method. As a template, water-soluble polymers, polymeric microgels, latex particles or bulk gels can be used. The morphology and properties of the composite particles can be controlled effectively by the proper use of the template. By choosing the dopant anion or oxidation agent it is possible to vary the conductivity of the polymer. In the case when uncrosslinked PVME was used as stabilizer, core-type polypyrrole spherical particles in the range of 50-100 nm were formed in both aqueous ethanol and water. Results of the elementary analysis, IR spectroscopy confirmed that the anionic salts can be incorporated in the PPy particles and play as the dopants. The presence of dopants in polypyrrole enhances the conductivity, especially in the case of sodium benzoate the conductivity of the final product has been improved by 3 orders. Polymeric microgels were also applied as the templates for polypyrrole deposition. When crosslinked PVME microgels were used in the oxidation polymerization of pyrrole, large PPy fibrils (appr. 400nm) were formed. Needle-like particles were formed due to the porous structure of microgels, which play a template role in the pyrrole polymerization process. When poly(VCL/AAEM) microgels were used as a template for oxidative polymerization of pyrrole, "raspberry-like" composite particles will be formed with PPy domains located in swollen hydropholic particle shell. Obtained stable composite microgels show similar thermal sensitivity as poly(VCL/AAEM) particles with fully reversible collapse-swelling properties. Increase of PPy content in composite particles increases conductivity of the composite material. The conductivity of composite particles prepared in water was much higher than that of prepared in water : ethanol mixtures. Furthermore, monodisperse PS-PEGMA particles, which were prepared in water medium by polymerization with sodium peroxydisulfate have been used as a template for deposition of polypyrrole (PPy). Obtained composite particles possess core-shell morphology where shell is composed out of small PPy nano-domains. The shell thickness can be varied by changing PPy load, controlling the overall template surface area in the system, and by influencing the pyrrole polymerization kinetics in presence of different oxidants. The last possibility provides also incorporation of different anions into polypyrrole shell. The stability of composite particles decreases gradually if the deposited PPy amount increases. It has been established that obtained particles are intrinsically coloured and the colour can be changed by the PS-PEGMA core size. Conductivity measurement shows that PS/PEGMA/PPy composite particles prepared by using phosphomolybdate as the oxidant are much more conductive than the particles prepared by the other two oxidants. The conductivity increases with the increase of PPy load in the system. Overall, the proper design of the template should give a possibility to control effectively the morphology, particle size and provide sufficient stability to the composite particles. Different morphologies, such as spherical, core-shell, raspberry and needle-like, with different particle size are expected to be available in different cases. By choosing the dopant anion or oxidation agent it is possible to vary the conductivity of the polymer. The stable water-based dispersions are expected to be used as additives for paint formulations, in electrorheology, microelectronic, ion-separation or disease diagnostics.
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Lu, Yan. "Polypyrrole containing composite particles: preparation, characterization and application." Doctoral thesis, [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974241083.
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Lamberterie, Pierre de. "Electrode composite hydrure métallique... réalisation, étude et application." Grenoble : ANRT, 1985. http://catalogue.bnf.fr/ark:/12148/cb37594877t.
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Adusei, Paa Kwasi. "Carbon Nanotube-Based Composite Fibers for Supercapacitor Application." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1561996824580323.
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Cerisier, Ambre. "Prédiction du comportement d'une réparation structurale collée en escalier : application d'une méthodologie par évaluateurs technologiques." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30120/document.
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La réparation collée est une problématique d'actualité compte tenu de la part croissante des matériaux composites dans les structures primaires aéronautiques. La littérature ouverte sur le sujet concerne des éprouvettes de taille élémentaire. Ce travail se propose de concevoir un évaluateur technologique représentatif de problématiques de grandes dimensions permettant d'étudier l'influence des procédés d'obtention sur le comportement de l'interface collée d'une réparation structurale en escalier. Afin d'atteindre cet objectif, une grande partie du travail consiste en la mise en place d'une stratégie numérique dite " légère " adaptée à l'étude de structures réparées multi-marches de taille représentative. Ce travail numérique se nourrit d'études préliminaires effectuées sur des éprouvettes élémentaires qui permettent de dégager un indicateur de rupture mixte du film adhésif. Une fois les choix numériques validés, ils sont appliqués pour la conception d'un évaluateur ainsi que d'une cinématique de chargement destinée à solliciter jusqu'à rupture la zone de collage en conditions choisies. L'évaluateur et sa cinématique sont testés grâce à un bâti multiaxial associé à une multi-instrumentationBonded repair is an issue more and more brought to attention in the aeronautical industry due to the rise of composite materials in primary structures. If most studies in the literature are focused on bonded interface on small-sized coupons, this PhD dissertation intends to design a technological evaluator that represents issues due to their wide sizes, which would enable the study of the influence of several processes on the behavior of the bonded interface of a structural step-lap repair. In order to reach this goal, a major part of the work involved the setting up of a numerical strategy, light in CPU time and adapted to the study of a multi-step repaired structure, with representative dimensions. This numerical step is fed by upstream studies, done on coupons, and that lead us to find a mixed failure indicator of the adhesive film. Once the numerical choices validated, they were applied to find the design of a technological evaluator, as well as its loading kinematics, meant to place the latter in a representative industrial situation. They were both tested thanks to a multi axial test machine
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Darroman, Emilie. "Elaboration de polymères biosourcés pour application dans un matériau composite à base de farine de liège." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2014. http://www.theses.fr/2014ENCM0018.
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Les travaux présentés concernent le développement d'un matériau composite (farine de liège, liant et additif) pour l'élaboration de bouchons technologiques mis en œuvre par un procédé de moulage. Dans le cadre de ces travaux, la synthèse, la caractérisation et la formulation d'un polymère biosourcé ont été développées en tant que liant de ce matériau composite. La stratégie de cette thèse a été de développer un polymère obtenu par polycondensation d'un composé époxydique avec un agent réticulant de type amine. Dans un premier temps, une caractérisation approfondie du liant utilisé par DIAM Bouchage a été réalisée pour définir le cahier des charges du nouveau polymère. L'étude de composés époxydiques et amines ont permis de sélectionner des précurseurs commerciaux biosourcés et non-classés CMR qui répondent au cahier des charges. De nouveaux précurseurs époxydiques et amines ont été synthétisés à partir de bioressources telles que la vanilline et les dérivés d'acide gras. La synthèse de résines époxy-amines a été effectuée grâce aux précurseurs commerciaux sélectionnés et ces résines ont été caractérisées thermiquement, mécaniquement et physiquement. Finalement, des bouchons technologiques ont été synthétisés selon différentes formulations et caractérisés pour évaluer leur adéquation avec les spécifications de DIAM BouchageThe presented study concerns the development of a composite material (cork flour, binder and additive) in order to produce of technological cork-stoppers carried out by a molding process. As part of this work, the synthesis, the characterization and the formulation of a biobased polymer have been developed as a binder of the composite material. The strategy of this thesis was to develop a polymer obtained by polycondensation of an epoxy compound with an amine curing agent.As a first step, a thorough characterization of the binder used by DIAM Bouchage was carried out to define the specifications of the novel polymer. The study of epoxy and amine compounds led to the selection of biobased commercial and non-classified CMR precursors that meet the specifications. Novel epoxy and amine precursors were synthesized from biobased resources such as vanillin and fatty acid derivatives. The synthesis of epoxy-amine resins was performed with the selected commercial precursors and these resins were characterized thermally, mechanically and physically. Finally, different formulations of technological cork-stoppers were synthesized and characterized to evaluate their suitability with the DIAM Bouchage specifications
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Ritter, William Joseph. "Application of energy methods to modeling failures in composite materials and structures." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/ritter/RitterW0805.pdf.
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Lee, Bok W. "Application of variational-asymptotical method to laminated composite plates." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/20695.
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Sonambekar, Abhijit Arvind Soschinske Kurt. "Analysis of GFRP composite tubes for vertical pump application." Diss., Click here for available full-text of this thesis, 2006. http://library.wichita.edu/digitallibrary/etd/2006/t001.pdf.
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Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering."May 2006." Title from PDF title page (viewed on October 2, 2006). Thesis adviser: Kurt Soschinske. Includes bibliographic references (leaves 87-90).
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Oh, Jungmin. "Preparation and application of conducting polymer-carbon nanotube composite." [Johnson City, Tenn. : East Tennessee State University], 2004. https://dc.etsu.edu/etd/960.
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Thesis (M.S.)--East Tennessee State University, 2004.Title from electronic submission form. ETSU ETD database URN: etd-1110104-211520 Includes bibliographical references. Also available via Internet at the UMI web site.
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Mohd, Zawawi Fazila. "Analyse aéroélastique d'une pale flexible composite : application au microdrone." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0027/document.
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The vision driving the work reported herein is to investigate the fluid-structure interac-tion (FSI) effects of the flexible laminated blades for tilt-body micro-air-vehicles (MAV)proprotors in hover and forward flight configurations. This is in order to exploit the po-tential of flexible-bladed proprotor over the rigid-bladed proprotor in the enhancementof proprotor performance during hovering and cruising at a target forward speed. Forthat, the FSI model taking into account the specific problems devoted to MAV-sizedproprotor made of laminate composite was developed. The FSI model combines aerody-namic model adapting Blade Element Momentum (BEM) theory and structural modeladapting Anisotropic Finite Element Beam (AFEM) theory. The aerodynamic model isdeveloped to be capable of adapting in the analysis on low Reynolds number proprotors.In the structural model, the blade is modeled as an elastic beam undergoing deflectionsin flap, lag, and torsion to capture the coupling effects in anisotropic materials, adaptsthe structural analysis on proprotor blades made of laminate composite. The reliabilityof the developed FSI model is verified through a validation on both aerodynamic andstructural models, separately, on several MAV-sized proprotors. As for a direction to theanalysis on passively-adaptive proprotor blades, an optimal design on actively-adaptiveproprotor was carried out. For this, a program for designing the optimum rigid blades atsingle-point (for either isolated cruise-point or isolated hover-point) and multiple-point(combined cruise and hover point) for proprotors have been developed. The proceduresin the optimal design program employs the numerical iterative inverse design method,based upon the minimum thrust induced losses (MIL). Even if the work in this thesiswas directed primarily towards the proprotor, however, the propulsion system from themotor part was not neglected since the propulsion efficiency is a crucial factor to the suc-cess of MAVs. A cheap and time-effective method of proposing the best motor from theselected commercial motors was developed, based on Taguchi’s method. The sensitivityof the total power consumption to the variation of value of each motor design variableswas also studied. The benefit of the use of tip body in the blade and the effect of bendingon the induced twist and on the thrust degradation, respectively, were also analyzed andidentified. Finally, the systematically designed passively-adaptive composite proprotors were evaluated under steady operating conditions. Hovering and cruise propulsive performance, characterized by total power Ptotal, were compared between the rigid-bladed and flexible-bladed proprotors. As a result of the comparison, the flexible-bladed proprotor with fixed system is found to be capable of slightly enhancing the performance through the reduction in Ptotal over its optimal rigid-bladed proprotorL’idée principale du travail rapporté ici est d’étudier les effets de l’intéraction fluide-structure (FSI) de pales laminées flexibles pour les proprotors de micro véhicules aériens(MAV) de type tilt-body dans les configurations de vol stationnaire et en avant. Eneffet, le but est d’exploiter les possibilités offertes par les proprotors à pales flexiblespar rapport aux proprotors à pales rigides pour améliorer leur performance dans cesphases de vol. Le modèle FSI a été développé à cet effet. Ce modèle tient compte desproblèmes spécifiques liés aux proprotors de MAV faits de composite laminé. Il com-bine l’adaptation de modèle aérodynamique par la théorie d’élement de pale (BEM) etl’adaptation de modèle structurel par la théorie des éléments finis de poutre anisotropes(AFEM). Le modèle aérodynamique est développé pour être capable de s’adapter àl’analyse des proprotors à bas nombres de Reynolds. Dans le modèle structural, la paleest modélisée comme une poutre élastique subissant des déviations dans la flexion, latraction et la torsion afin de capturer les effets de couplage de matériaux anisotropes.Il adapte l’analyse structurale des pales du proprotor faites de composite laminé. Lafiabilité du modèle FSI développé est vérifiée à travers une validation par modèles aéro-dynamique et structural, séparément, sur plusieurs proprotors de MAV. Afin de se dirigervers une analyse de pales de proprotors à adaptation passive , une recherche de designoptimal a été effectuée pour des proprotor à adaptation active. Pour cela, un programmepour la conception de pales rigides optimales à un unique point de fonctionnement (soitle vol de croisière soit le vol stationnaire) et à plusieurs points (combinant croisière etvol stationnaire) ont été développés. Les procédures du programme de design optimalemploient les mèthodes de design inverse par itération numérique, sur la base de pertesde poussée induites minimales (MIL). Même si le travail dans cette thèse a été dirigéprincipalement vers le proprotor, la partie moteur du système de propulsion n’a pasété négligée puisque l’efficacité de la propulsion est un facteur crucial pour le succès desMAVs. Une méthode simple et rapide de sélection du meilleur moteur parmi les moteurscommerciaux choisis est élaborée sur la base de la méthode de Taguchi. La sensibilitéde la consommation d’énergie totale à la variation de la valeur de chaque variable deconception du moteur a été étudiée. Le bénéfice de l’utilisation de la charge à la pointe de la pale et l’effet de la flexion sur la torsion induite et sur la dégradation de la poussée respectivement ont aussi été analysés et identifiés. Enfin, les proprotors à pales flexibles conçues systématiquement ont été évalués dans des conditions de fonctionnement stables. Performances en vol stationnaire et performances croisière propulsive, caractérisées par la puissance totale Ptotal ont été comparées entre les proprotors à pales rigides et à pales flexibles. En tant que résultat de la comparaison, les proprotors à pales flexibles s’avère capable d’améliorer légèrement les performances par la réduction de la Ptotal surson optimal proprotors à pales rigides
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Annamalai, Perushini. "Electrospinning of porous composite materials for hydrogen storage application." University of the Western Cape, 2016. http://hdl.handle.net/11394/5654.
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>Magister Scientiae - MScDue to the rapid depletion of fossil fuel reserves and the production of environmentally harmful by-products such as carbon dioxide, there is an urgent need for alternate sustainable clean energy. One of the leading candidates in this endeavour is hydrogen, which can be used as an energy carrier since it has a high energy density, zero emissions and is produced from non-depletable resources such as water. The major challenge hindering a hydrogen economy is the lack of safe and effective storage technologies for mobile applications. A prospective solution to this problem lies in the use of porous powdered materials, which adsorb the hydrogen gas. However, the integration of these powdered materials into a storage tank system, results in the pipelines being contaminated during filling cycles. This necessitates the shaping of the porous powdered materials. Among the many shaping techniques available, the electrospinning technique has been proposed as a promising technology since it is a versatile process that is easily scaled-up making it attractive for the applications of the study. Furthermore, the electrospinning process enables the synthesis of nano-sized fibres with attractive hydrogen sorption characteristics. In this regard, the current study employs the electrospinning technique to synthesise electrospun composite fibres for mobile hydrogen storage applications. After electrospinning three polymers, polyacrylonitrile (PAN) was selected as the most suitable polymer because it yielded bead-free electrospun fibres. However, the diameter of the PAN fibres was large/thick which prompted further optimisation of the electrospinning parameters. The optimised electrospinning conditions that yield unbeaded fibres within the desired diameter range (of 300-500 nm) were a PAN concentration of 10 wt%, a flow rate of 0.4 mL/h, a distance of 10 cm between the needle tip and collector plate, and an applied voltage of 8 kV. The study then progressed to the synthesis and characterisation of the pristine porous powdered materials which adsorb hydrogen gas. The porous powdered materials investigated were commercial zeolite 13X, its synthesised templated carbon derivative (ZTC) and Zr (UiO-66) and Cr (MIL-101) based metal-organic frameworks (MOFs). ZTC was synthesised via liquid impregnation coupled with chemical vapour deposition (CVD), and the MOFs were synthesised by the modulated solvothermal method. Analysis of the ZTCs morphology and phase crystallinity show that the carbon templated process using zeolites was successful, however, ZTC was amorphous compared to crystalline zeolite template. The BET surface area was assessed with the aid of nitrogen sorption isotherms for both zeolite 13X and ZTC, and values of 730 and 2717 m²/g, respectively were obtained. The hydrogen adsorption capacity for zeolite 13X was 1.6 wt% and increased to 2.4 wt% in the ZTC material at 77 K and 1 bar. The successful synthesis of well defined, crystalline MOFs was evident from X-ray diffraction and morphological analysis. The BET surface area and hydrogen adsorption for Zr MOF were 1186 m²/g and 1.5 wt%, respectively at 77 K and 1 bar. Cr MOF had a BET surface area of 2618 m²/g and hydrogen adsorption capacity of 1.9 wt% at 77 K and 1 bar. The main focus of the study was to synthesise electrospun composite fibres that can adsorb hydrogen gas and thus provide significant insight in this field of research. As such it examined composite fibres that incorporates porous powdered materials such as zeolite 13X, ZTCs, UiO-66 (Zr) MOF and MIL-101 (Cr) MOF and investigated their ability to adsorb hydrogen gas, which have not been reported previously. The synthesis of composite fibres was achieved by incorporating the porous powdered materials into the PAN resulting in a polymeric blend that was then electrospun. Morphological analysis illustrated that the porous powdered materials were successfully supported by or incorporated within the PAN fibres, forming composite fibres. The BET surface area of the 40 wt% zeolite-PAN and 12.5 wt% ZTC-PAN composite fibres were 440 and 1787 m²/g respectively. Zr MOF and Cr MOF composite fibres had a BET surface area of 815 and 1134 m²/g, respectively. The BET surface area had reduced by 40, 34, 31 and 57% for zeolite 13X, ZTC, Zr MOF and Cr MOF, respectively after these porous powdered materials were incorporated into PAN. The hydrogen adoption capacity for 40 wt% zeolite-PAN, 12.5 wt% ZTC-PAN, 20 wt% Zr MOFPAN and 20 wt% Cr MOF-PAN composite fibres was 0.8, 1.8, 0.9 and 1.1 wt%, respectively. This decrease was attributed to the limited amount of porous powdered materials that could be incorporated into the fibres since only 40 wt% of zeolite 13X, 12.5 wt% of ZTC and 20 wt% of the MOFs were loaded into their respective composite fibres. This was due to the fact that incorporation of greater amounts of porous powdered materials resulted in a viscous polymeric blend that was unable to be electrospun. It is evident from the study that electrospinning is a versatile process that is able to produce composite fibres with promising properties that can potentially advance the research in this field thus providing a practical solution to the problem of integrating loose powdered materials into an on-board hydrogen storage system.
CSIR Young Researchers Establishment Fund (YREF)
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Chelaghma, Saber Ayoub. "Fonctionnalisation de composites C/PEKK pour application aérospatiale : caractérisation, modélisation et influence sur les propriétés du composite." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30362.
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La réduction du poids des avions est l'un des grands défis de l'industrie aérospatiale. Afin d'atteindre les objectifs ambitieux en matière de consommation de carburant et de réduction des émissions, des composites renforcés de fibres de carbone, ont été introduits sur le marché. Ces matériaux suscitent un intérêt croissant, néanmoins, ils possèdent une faible conductivité électrique, ne permettant pas de garantir une protection contre la foudre. Pour cette raison, les composites chargés de particules conductrices font l'objet d'activités de recherche en cours. L'objectif est le développement de composites multifonctionnels avec des propriétés électriques accrues. Pour l'heure, la matrice thermoplastique de référence est le PEEK mais ce polymère reste toutefois cher, et sa température d'élaboration élevée. Dans ce but, des matrices thermoplastiques, telles que le PEKK, sont à nouveau étudiées. Entre la matière première et la pièce finale, la matrice thermoplastique subit plusieurs cycles de traitement à haute température (imprégnation, consolidation, procédés d'assemblage) au cours desquelles sa capacité à cristalliser évolue sans cesse. Afin d'évaluer l'impact du procédé et des constituants du composite sur les propriétés du composite, la cristallisation a fait l'objet d'une attention particulière. Deux dispositifs expérimentaux complémentaires ont été utilisés afin de caractériser la cristallisation : une platine chauffante, permettant d'appliquer un cycle thermique et d'observer la cristallisation en microscopie optique ainsi que la calorimétrie différentielle à balayage. L'influence des fibres de carbone et des particules conductrices sur la cinétique de cristallisation a été évaluée. Une diminution des temps de cristallisation a été observée à travers l'augmentation du taux de germination. Les données recueillies ont servi à développer un modèle de cinétique de cristallisation identifié à travers une approche originale en se basant sur des données microscopiques et enthalpiques. Ce modèle permet de prédire les cinétiques de cristallisation des composites à matrice PEKK mais il ne permet pas de rendre compte de la microstructure finale engendrée. Or, cette dernière a un impact non négligeable sur les propriétés mécaniques comme cela a été prouvé à travers des essais de nano-indentation. Pour prévoir la microstructure finale, un modèle basé sur l'approche pixel coloring a été développé. L'influence des fibres de carbone a été introduite à travers la formation d'une phase transcristalline. Une bonne corrélation est constatée entre l'approche analytique, la simulation et les données expérimentales en termes de cinétique de cristallisation. Des caractérisations mécaniques et électriques ont été effectuées afin d'évaluer les performances de ces nouveaux matériaux. Sur les matériaux étudiés, la réponse mécanique n'est pas homogène comme observé sur des essais de traction suivis en stéréo-corrélation. L'étude de la santé matière montre l'existence de défauts, en particulier, à l'échelle de la microstructure. Afin de prendre en compte ces particularités, il est ainsi nécessaire de décrire plus finement la microstructure. Pour cela, la tomographie à rayons X a été utilisée afin de caractériser le composite. Les récents développements de cette technique permettent, en combinaison avec des outils de segmentation, de reconstruire une géométrie représentative du matériau. Cette géométrie est utilisée pour simuler le comportement mécanique ainsi que la cristallisation. Les simulations numériques d'un VER sont capables de prédire les propriétés d'un pli, puis celles du stratifié. Cette modélisation multi-échelle pourrait réduire le nombre et le coût des campagnes expérimentales. Ainsi, déterminer les propriétés de la structure finale en se basant sur des caractérisations et simulations à l'échelle de la microstructure est un enjeu scientifique et industriel stratégique. Ce travail constitue une contribution vers cette approcheReducing aircraft weight is one of the major challenges facing the aerospace industry. In order to achieve the ambitious goals of fuel consumption and emission reduction, carbon-fiber reinforced composites have been introduced to the market. These materials are attracting increasing interest, however, they have low electrical conductivity to ensure protection against lightning strike. For this reason, composites filled with conductive particles are the subject of ongoing research activities. The objective is the development of multifunctional composites with enhanced electrical properties. Actually, the most used thermoplastic matrix is PEEK, but this polymer remains expensive, and its processing temperature is high. For this purpose, thermoplastic matrices, such as PEKK, are again studied. Between the raw material and the final part, the thermoplastic matrix undergoes several thermal steps with high temperature exposure (impregnation, consolidation, forming and assembly processes) during which its ability to crystallize evolves continuously. In order to evaluate the impact of the process and the composite constituents on its properties, crystallization has been the subject of particular attention. Two complementary experimental devices were used to characterize the crystallization. The heating stage, allows to apply a thermal cycle and observe the crystallization in optical microscopy and differential scanning calorimetry. The influence of carbon fibers and conductive fillers on the crystallization kinetics was evaluated. A decrease in crystallization times was observed through the increase of the nucleation rate. The collected data were used to develop a kinetic model identified through an original approach based on microscopic data. This model makes it possible to predict the crystallization kinetics of PEKK composites. Nevertheless, it does not make it possible to predict the final microstructure. However, the microstructure has a significant impact on mechanical properties as it has been proven through nano-indentation tests. To predict the final microstructure, a model based on the pixel coloring approach has been developed. The influence of carbon fibers has been introduced through the formation of a transcrystalline phase. A good correlation is found between the analytical approach, the simulation and the experimental data in terms of crystallization kinetics. Mechanical and electrical characterizations were performed to evaluate the performance of these new materials. On the studied materials, the mechanical response is not homogeneous as observed on tensile tests followed in stereo-correlation. The study of matter health shows the existence of defects, in particular, at the microstructure level. In order to take this particularity into account, it is thus necessary to describe the microstructure more finely. For this, X-ray tomography was used to characterize the composite. Recent developments in this technique allow, in combination with segmentation tools, to reconstruct a representative geometry of the material. This geometry is used to simulate the mechanical behaviour as well as the crystallization. The numerical simulations of an RVE are able to calculate the properties of a ply, then those of a laminate. This multi-scale modelling could reduce the number and cost of experimental campaigns. Thus, determining the properties of the final structure based on characterizations and simulation at the microstructure scale is a strategic scientific and industrial issue. This work is a contribution towards this approach
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Malenfant, Jean-Charles. "Influence de l’endommagement sur la perméabilité des matériaux composites : application à la conception d’une capacité cryogénique sans liner." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14550/document.
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Ce travail de thèse s’est déroulé dans le cadre du projet de nanolanceur à propulsion hybride PERSEUS du CNES. La performance de ce concept est influencée par l’allègement de la structure du lanceur. La voie de développement qui a été choisie est de supprimer le liner du réservoir composite cryogénique. Elle repose sur trois exigences fonctionnelles : la compatibilité du matériau composite avec l’oxygène liquide (LOX), l’étanchéité du réservoir, et la résistance aux sollicitations thermomécaniques.L’étude de la compatibilité LOX des matériaux composites met en évidence l’importance du transfert de chaleur au sein du composite et plus précisément de la conductivité thermique des fibres. Ce résultat théorique est conforté par l’expérimentation.Le verrou scientifique principal du travail de thèse concerne l'influence de l’endommagement du composite sur la perméabilité de ce dernier. La conception de dispositifs expérimentaux a permis de déterminer l’évolution des endommagements (fissuration transverse, micro-délaminage, ouverture de fissure) et celle de la perméabilité. Un modèle complet de prévision de la perméabilité d’une paroi composite sollicitée thermo-mécaniquement est proposé. Il s’articule autour d’un modèle d’endommagement à l’échelle du pli, d’un modèle de prédiction de l'ouverture des fissures, et d’un modèle d’écoulement en milieu poreux. La pertinence du modèle développé est testée à travers la réalisation d’un démonstrateur technologique sans liner et d’une campagne d’essais d’endommagement et de mesure de perméabilitéThis thesis deals with hybrid propulsion launcher systems studied by the CNES (Centre National d'Etudes Spatiales). The performance of the launcher implies its lightening and in this work, the use of a cryogenic composite linerless tank is evaluated. Three functional requirements must be satisfied: the compatibility between the composite material and the liquid oxygen (LOX), the tank gas-tightness and the strength under pressure.The LOX compatibility of composite materials implies high thermal conductivity of the composite, and consequently of the fiber reinforcement. This theoretical result is confirmed by experiments.The main scientific challenge concerns the damage influence on the composite permeability. Specific experimental devices allow determining the damage evolution (transverse cracking, delamination, opening crack) and the composite permeability. A predictive composite permeability model is applied to a composite wall under thermomechanical load: this model includes a ply-scale damage model, a predictive opening crack model and a model of flow through porous media. The relevance of the model is validated through the realization of a linerless prototype tank and the associated tests which correlate damage and permeability
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Lasseigne, Alexis. "Optimization of variable-thickness composite structures. Application to a CROR blade." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM006/document.
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Cette thèse aborde la problématique de la conception optimale de structures composites stratifiées d’épaisseur variable. Les variables d’empilement définissent un problème d’optimisation combinatoire et des espaces de décisions de grande taille et potentiellement multimodaux. Les algorithmes d’optimisation stochastiques permettent de traiter ce type de problème et de tirer profit des performances et de l’anisotropie des plis composites pour l’allègement des structures composites stratifiées. Le but de cette étude est double : (i) développer un algorithme d’optimisation dédié aux composites stratifiés d’épaisseur variable et (ii) estimer le potentiel des composites stratifiés pour la maîtrise des performances aérodynamiques d’une pale de CROR composite.Dans la première partie de cette thèse, un algorithme évolutionnaire est spécialisé pour l’optimisation de tables de drapage et la gestion d’un ensemble de règles de conception représentatif des pratiques de l’industrie. Pour se faire, un encodage spécifique des solutions est proposé et des opérateurs de variations spécialisés sont développés.Dans la deuxième partie, l’algorithme est enrichi d’une technique de guidage basée sur l’exploitation d’un espace auxiliaire afin d'accroître son efficacité et d’intégrer davantage de connaissances des composites dans la résolution du problème.Finalement, la méthode est appliquée pour la conception d’une pale de CROR composite à l’échelle de la maquette de soufflerie. Au préalable, des processus itératifs de mise à froid et mise à chaud de la pale sont mis en place afin d’estimer la forme de la pale au repos et l’état de contraintes dans la pale en fonctionnementThis thesis deals with the optimal design of variable-thickness laminated composite structures. The stacking variables define a combinatorial optimization problem and large decision spaces which are potentially multimodal. Stochastic optimization algorithms allow solving this type of problem and allow taking advantage from the performance and the anisotropic nature of unidirectional composite plies to lighten laminated composite structures.The purpose of this study is twofold: (i) developing an optimization algorithm dedicated to variable-thickness laminated composites and (ii) assessing the potential of laminated composites in influencing the aerodynamic performances of a composite CROR blade.Firstly, an evolutionary algorithm is specialized in order to optimize layup tables and handle a set of design guidelines which is representative of industrial practices. In this purpose, a specific encoding of the solutions is suggested and specialized variation operators are developed.Secondly, the algorithm is enriched with a guiding technique based on the exploitation of an auxiliary space in order to improve its efficiency and to include further composites-related knowledge for the resolution of the problem.Finally, the method is applied for the design of a reduced-scale composite CROR blade intended for wind-tunnel testing. Beforehand, iterative processes are implemented to estimate the shape of the non-operating blade and the stress state within the operating blade
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Mouillat, Claire G. J. "Application of UV curing to the preparation of composite materials." Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360968.
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Morin, Craig R. (Craig Robert). "The application of composite laminates in strengthening concrete cross ties." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10736.
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O'Donnell, Matthew Philip. "Exploiting non-symmetry in composite laminates : application to stringer terminations." Thesis, University of Bristol, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659112.
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This thesis challenges the existing composite design paradigm that prohibits the use of non-symmetric laminates. The restrictive nature of "symmetric-only" stacking sequences is identified, highlighting the potential benefit for structural optimisation on relaxing this constraint. The thermal response of such laminates during manufacture is investigated , noting layup induced variation of the coefficients of thermal expansion is often cited as a' major objection to their use. By extending known results for warp-free non-symmetric laminates, it is shown that flattening of (some) moderately warped plates induces nominal build strain . Allowing a tolerance to non-symmetry induced warping is presented in terms of increased design space for a specified level of induced strain. The direct benefits of non-symmetry, taking advantage of the coupling between in and out-of-plane responses, is also considered. The increased performance of non-symmetric configurations observed in this thesis counters the perceived wisdom that this coupling is always unfavourable. Specifically, moderately non-symmetric laminates indicate the potential to increase the load carrying capacity of stringer terminations. This was achieved by improving the resistance to debonding as investigated using both analytical and finite element techniques. To better understand the underlying mechanisms, and the effect of non-symmetry on stringer termination design, an optimisation framework is proposed. An established Ritz-Galerkin hybrid model is employed to predict structural response, in conjunction with analytical debonding and buckling constraints . A two-step process, making use of lamination parameters and genetic algorithms, is able to find optimised designs. Significant improvements over the quasi-isotropic configuration are observed including a preference towards non-symmetric configurations. Previously unknown limitations of the Ritz-Galerkin approach are identified during this study. The choice of basis functions a re discussed a long with the validity of implicit assumptions made regarding the geometric non-symmetry and energy formulation. A more general, non-dimensional, Ritz based model was proposed to mitigate these limitations. Although a general improvement is observed, there are further complexities in capturing localised behaviour due to stiffness discontinuities. A series of further refinements and investigations a re proposed as future directions of research. Finally, via the use of Legendre polynomials, it is possible to reformulate the Ritz method using the "triple-product" approach. Such an approach transforms the problem into a summation of standardised integrals containing three term products of the basis functions. Exploiting previously unused - in structural engineering - algebraic recursion relations a significant increase in computational performance can be realised . The number of numerical integrations that must be performed is shown to reduce by an order of magnitude. This result is significant for the analysis and optimisation of any variable stiffness plate/ shell-like structure where calculating these integrals often dominates the computational expense of analysis.
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Liang, Yating. "Nonlinear analysis of composite shells with application to glass structures." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/44335.
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Laminated glass is a special composite material, which is characterised by an alternating stiff/soft lay-up owing to the significant stiffness mismatch between glass and PVB. This work is motivated by the need for an efficient and accurate nonlinear model for the analysis of laminated glass structures, which describes well the through-thickness variation of displacement fields and the transverse shear strains and enables large displacement analysis. An efficient lamination model is proposed for the analysis of laminated composites with an alternating stiff/soft lay-up, where the zigzag variation of planar displacements is taken into account by adding to the Reissner-Mindlin formulation a specific set of zigzag functions. Furthermore, a piecewise linear through-thickness distribution of the material transverse shear strain is assumed, which agrees well with the real distribution, yet it avoids layer coupling by not imposing continuity constraints on transverse shear stresses. Local formulations of curved multi-layer shell elements are established employing the proposed lamination model, which are framed within local co-rotational systems to allow large displacement analysis for small-strain problems. In order to eliminate the locking phenomenon for the shell elements, an assumed strain method is employed and improved, which readily addresses shear locking, membrane locking, and distortion locking for each constitutive layer. Furthermore, a local shell system is proposed for the direct definition of the additional zigzag displacement fields and associated parameters, which allows the additional displacement variables to be coupled directly between adjacent elements without being subject to the large displacement co-rotational transformations. The developed multi-layer shell elements are employed in this work for typical laminated glass problems, including double glazing systems for which a novel volume-pressure control algorithm is proposed. Several case studies are finally presented to illustrate the effectiveness and efficiency of the proposed modelling approach for the nonlinear analysis of glass structures.
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Shrestha, Umesh Shahu. "Modified Composite Application to Improve Strength and Ductility ofStructural Components." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1418403567.
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Smolikov, A. A., V. M. Beresnev, A. I. Vesentsev, A. D. Kolesnikov, and A. S. Solokha. "Perspectives of application of nanotubes in modern composite building materials." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20636.
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There are described the perspectives of application a carbon and hydro silicate nanotubes in modern compositional materials.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20636
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Smolikov, A. A., V. M. Beresnev, A. I. Vesentsev, D. A. Kolesnikov, and A. S. Solokha. "Perspectives of application of nanotubes in modern composite building materials." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20770.
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PHATAK, DEEPTI DILIP. "CHARACTERISTICS OF 2-2 POLYIMIDE/PZT COMPOSITE FILMS ON Pt/Si SUBSTRATE." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1029338020.
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Gabrion, Xavier. "Contributions à la caractérisation d'un matériau composite thermoplastique thermostable : Application à des structures cylindriques sous sollicitations multiaxiales." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2012.
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Ce travail de thèse, en partenariat avec l’entreprise ALSTOM, s’inscrit dans une logique de remplacement de pièces industrielles en alliage métallique par des pièces composites pour l’allègement des structures. L’objectif est de contribuer à l’écriture de règles de dimensionnement permettant au partenaire industriel de certifier des pièces structurales annulaires réalisées en composite à matrice thermoplastique thermostable (TPTS) renforcée par des fibres de carbone pour des applications embarquées sur machine tournante. Il s’agit plus exactement de déterminer la durée de vieen fatigue de ces pièces, en particulier en présence d’endommagement, et lorsque celles -ci sont soumises aux chargements inertiels et thermiques de service.Au cours de ce travail de thèse, une méthodologie a été développée afin de répondre à cette demande. La stratégie a consisté à reproduire,à l’échelle d’éprouvettes de laboratoire, l’état de contrainte multi-axial et l’endommagement auxquels la structure industrielle est soumise, et ce en développant et optimisant un essai de traction sur des éprouvettes annulaires entaillées. Les essais multi axiaux plus classiques mettant en œuvre des sollicitations par pression interne présentent effectivement de nombreux problèmes techniques et sécuritaires lorsqu’ils doivent être mis en œuvre à chaud.Une fois la configuration d’essai sur anneau optimisé par simulation numérique, des essais ont été réalisés afin de confirmer l’apparition des endommagements escomptés à l’aide de techniques de contrôle non-destructif. Les essais cycliques réalisés dans cette configuration ont montré une excellente résistance du matériau en fatigue, en particulier pour un ratio de chargement R de 0.5, proche des conditions de service. Les résultats ont également soulignés le fort potentiel restant de ces structures, même après un grand nombre de cycles de chargementThe objective of this thesis work, in partnership with ALSTOM Company, is to contribute to the writing of design rules in order to qualify and certify annular structures made of thermostable thermoplastic matrix composite reinforced by carbon fibre. These structures are used in rotating machines for embedded applications.This work proposes an innovative methodology to achieve this goal. It consists in reproducing, at the scale of a laboratory specimen, the multiaxial stress and damage states to which the industrial structure is subjected in-service byoptimizing a tensile test on annular notched specimen. More conventional multiaxial tests, based on internal pressureand tensile loading are particularly unsafe and difficult to be performedwhen implemented at elevated temperature.After the optimisation of the ring configuration by numerical simulation, experimental tests were performed to validatethe appearance of the expected damage under loading. Damage was characterized using non-destructive techniques suchas acoustic emission and infrared thermography. The cyclic tests achieved using this configuration showed high fatiguestrength of this material, in particular for a ratio R of 0.5 (equivalent to thein-service ratio). The results also highlight thegreat remaining strength and rigidity of these structures, even after a large number of cycles
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Pascal, Florian. "Modélisation d'impacts sur structures sandwichs composites : application aux pales d'hélicoptères." Toulouse 3, 2016. http://www.theses.fr/2016TOU30271.
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Les pales d'hélicoptère sont des pièces composites complexes qui assurent la sustentation de l'appareil. En phase de vol, un impact sur ce type de structure peurt engendrer des dommages importants dont les conséquences peuvent être critiques pour l'appareil. Du fait de l'angle d'incidence des pales, la zone intrados est particulièrement exposée à ce type de sollicitation. Cette thèse a pour objectif de développer un modèle d'impact fiable et prédictif qui vise à mieux comprendre les mécanismes d'endommagement mis en jeu pour, à termes, proposer de nouvelles architectures de palesHelicopter blades are complex composite stuctures that provide the lift necessary to sustain flight. Impacts on the blade in flight can lead to significant damage that can be critical for the aircraft. Due to the angle of incidence of the blades, the lower surface area is particulary vulnerable to impact loadings. This study aims to develop a reliable and predictive impact modelling dedicated to a better understanding of the damage mechanisms involved and eventually able to provide guidance for new blade concepts
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Guyader, Guillaume. "Contribution à l’étude des conditions de tressage d’armures textiles hautes performances : application à l’identification des rigidités élastiques de coques composites 2D et 3D." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10299.
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A partir d'un bilan bibliographique portant sur les enjeux du développement des composites dans le secteur automobile et en examinant les problèmes scientifiques et techniques posés par l'utilisation des armures textiles 2D et 3D pour la prévision des propriétés en rigidité de composites tressés, notre recherche s'articule autour de trois axes : Dans une première partie, nous cherchons à décrire les différentes phases de l'opération de tressage en identifiant les principaux paramètres du procédé industriel qui influencent le positionnement et la structuration géométrique de l'armure textile. Nous proposons une formulation analytique originale de la trajectoire des fils sur le mandrin et nous sommes en mesure de simuler l'influence des différents paramètres de tressage sur la description du positionnement géométrique des fils au sein du VER des composites tressés. Dans une seconde étape, nous développerons une procédure d'analyse expérimentale sur des éléments de structures « modèle » tressés en prenant en considération des conditions de chargement complexe pour mettre en évidence les effets induits par les hétérogénéités et les facteurs d'anisotropie des renforts textiles. Cette phase expérimentale permet de proposer et valider, dans une troisième étape, une méthode de calcul des caractéristiques mécaniques globales en rigidité basée sur l'analogie avec les composites stratifiés prenant en considération l'ondulation des fils dans les propriétés intrinsèques des plis individuelsIn the first part of the thesis, based on literature results, we synthesize the main difficulties that limit the development of composite materials for automotive applications. Furthermore, we examine what are the scientific and technical issues for the prediction of the mechanical performances of braided technical textiles. Consequently, our effective research work follows three main axes: In a first phase, we analyse different parameters that influence the braiding process, and we propose a new analytical formulation describing the yarn positioning on complex shaped mandrels. In a second phase, we perform an experimental analysis of the mechanical properties of braided composites testing tubular structures under complex loading conditions, to evaluate the influence of internal heterogeneousness on the structural behaviour. In the last phase, we consider and validate a modelling approach where numerical results are obtained from laminated composite theory, taking into account the local orientation of yarns. Finally, we are able to suggest different optimised design ways applied to braided composites structures
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Yang, Cheng. "Explorations in the application of nanotechnology to improve the mechanical properties of composite materials /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202007%20YANG.
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Barbu, L. G. (Lucia Gratiela). "Numerical simulation of fatigue processes : application to steel and composite structures." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/386479.
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The present thesis aims at advancing an innovative computational methodology that simulates steel and composite material fracture under cyclic loading following a phenomenological approach, with calibration from both small scale and large scale testing. This work addresses fatigue processes ranging from high cycle to ultra-low-cycle fatigue. An assessment of the current state of the art is done for all the different fatigue types. Following, for ultra-low cycle fatigue a new constitutive law is proposed and validated with experimental results obtained on small scale samples. Industrial applications are shown for a large diameter straight pipe under monotonic loading conditions and for a bent pipe under cyclic loading. Emphasis is made on the capacity of the model to represent different failure modes depending on the loading conditions. The research regarding this part has been used in the frame of the European Project: ¿Ultra low cycle fatigue of steel under cyclic high-strain loading conditions¿ (ULCF).
Regarding high cycle fatigue, a classic damage model is presented in combination with an automatic load advancing strategy that saves computational time when dealing with load histories of millions of cycles. Numerical examples are shown in order to demonstrate the capabilities of the advancing strategy and a validation of the model is done on small scale samples.
A new constitutive model is presented for Low Cycle Fatigue that uses the classic plasticity and damage theories and simultaneously integrates both processes in the softening regime. The capabilities of the model are shown in numerical examples.
Finally, the high cycle fatigue damage model is applied to the constituents of a composite material and the structural behaviour is obtained by means of the serial/parallel rule of mixtures. Validation of the constitutive formulation is done on pultruded glass fiber reinforced polymer profiles.La presente tesis propone una metodología innovadora para la simulación numérica de la rotura de materiales metálicos y compuestos sometidos a cargas cíclicas. El enfoque es fenomenológico y la formulación se calibra con resultados experimentales obtenidos en especímenes a pequeña escala y con experimentos a gran escala. Este trabajo abarca procesos de fatiga desde alto número de ciclos hasta muy bajo número de ciclos. Una evaluación del estado del arte hasta el momento se ha llevado a cabo para los diferentes tipos de fatiga. A continuación, se propone una nueva ley constitutiva para la fatiga de muy bajo número de ciclos y se presenta la validación con resultados experimentales obtenidos en especímenes a escala pequeña. El modelo constitutivo se ha probado en dos aplicaciones industriales: una tubería de gran diámetro bajo condiciones de carga monótonas y una tubería doblada a un ángulo de 90 grados sometida a cargas cíclicas. Se ha enfatizado la capacidad del modelo de reproducir diferentes modos de rotura dependiendo de las condiciones de carga. El trabajo referente a este modelo se ha usado en el marco del proyecto europeo: ¿Fatiga de muy bajo número de ciclos del acero bajo grandes deformaciones cíclicas¿. Respecto a la fatiga de alto número de ciclos, se presenta un modelo clásico de daño combinado con una estrategia automatizada de avance en la carga por número de ciclos. La estrategia conduce a un ahorro en tiempo de computación cuando se aplican millones de ciclos de carga. Las capacidades y particularidades de la estrategia de avance en la carga se enseñan en una serie de ejemplos numéricos. El modelo se valida con resultados experimentales obtenidos en especímenes a pequeña escala. Un nuevo modelo constitutivo se presenta para la fatiga de bajo número de ciclos que se basa en las teorías básicas de plasticidad y daño y que integra simultáneamente las ecuaciones de ambos procesos en el régimen de ablandamiento. Las capacidades del modelo se enseñan a través de ejemplos numéricos. Finalmente, se estudia la aplicación del modelo de daño para fatiga de alto número de ciclos en los componentes de materiales compuestos. El comportamiento estructural del material compuesto se obtiene a través de la teoría de mezclas serie/paralelo. La formulación se valida con resultados experimentales obtenidos en perfiles de GFRP.
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Cyr, Pierre. "Development of a computer application for optimization of composite material structures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0030/MQ64214.pdf.
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Hsu, Chia Chen, and 許家禎. "Application of Ultrasonic Machining to Composite Material." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/05892512040526627700.
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Xu, Jia-Zhen, and 許家禎. "Application of Ultrasonic Machining to Composite Material." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/10858212841443223361.
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Sundararajan, S. "Particulate Aluminium Matrix composite Material (Al-12 Si-SiCp) For I.C. Engine Piston Application." Thesis, 1996. http://etd.iisc.ernet.in/handle/2005/1593.
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Liu, Yi-You, and 劉伊祐. "Application of Superparamagnetic Poly(methyl methacrylate)/TiO2 Composite." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/81766858149891111183.
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碩士國立高雄應用科技大學
化學工程系碩士班
95
The nano-sized oleic acid-coated magnetite particles (OMP) and its magnetic poly(methyl methacrylate) (PMMA) microspheres were successfully prepared via co-precipitation method and suspension polymerization method, respectively. The nano-sized OMP mixed with methyl methacrylate (MMA) monomers and divinylbenzene were employed to produce the magnetic PMMA microspheres. The morphology and size of magnetic PMMA microspheres and OMP were observed by transmission electron micrograph (TEM), scanning electron microscopy (SEM), and particle size analyzer. The inorganic substance composition and magnetite content of magnetic PMMA microspheres and OMP were observed by wide angle x-ray diffraction (WAXD), and thermogravimetric analysis (TGA). The hysteresis loop, residual magnetism, and coercive force of magnetic PMMA microspheres and OMP were observed by superconductor quantum interference device (SQUID). Application of magnetic PMMA microspheres with titanium dioxide coated surface to degradation of p-phenylenediamine (PPD).
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Wong, Chia-Ching, and 翁嘉慶. "The Application of Thin-walled Composite Beam Element." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/59371868970524725935.
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碩士國立成功大學
航空太空工程學系
85
The main purpose of the present here is to analysis thethin-walled composite beam structures by using the thin- walledcomposite beam finite element developed by Wu and Sun, and compare the results with experimental data. The element has twonodes, 10 degrees of freedom per node. And it is suitable for either open-section or closed section beams of any shape, stacking sequence and boundary condition.
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Li, Yi-Shien, and 李宜諴. "Synthesis and Application of Silver-Copper Composite Nanoparticles." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/50961114538235955718.
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Hsieh, Meng-Yow, and 謝孟佑. "Application of Thermogel Composite for Bone Tissue Regeneration." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/564gm4.
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博士國立臺灣大學
醫學工程學研究所
105
Thermo-sensitive hydrogels are injectable fluids that can be introduced into the body in a minimally invasive manner prior to solidifying or gelling with the desired tissue or organ. Additionally, the thermos sensitive hydrogels own many advantages, such as it does not require organic solvents and can be an in-situ forming gel. Because of the simplicity of pharmaceutical and biomedical uses of the water-based sol-gel transition that can be used as drug delivery-control systems, bioactive compounds delivery, and tissue engineering. In this study we aimed the bone tissue repair. The first part was focused on avascular necrosis (AVN) treat with thermogel blend with BMP-2.From results showed that AVN surgery plus MP treatment has successfully reduced the damage of femoral head 4 weeks after treatment. A dosage of BMP-2 (1μg/mL) in hydrogel has effectively reduced the femoral damage induced by AVN surgery plus MP treatment by preserving more epiphysis of the femoral head and more trabeculae below the growth plate of the femoral head 8 weeks after treatment. Furthermore, BMP-2 in hydrogel attenuated the femoral head damage after AVN surgery plus MP treatment at doses of 1 and 2μg/mL. These findings strongly suggest that BMP-2 in the hydrogel has a great potential for treating patients suffering from avascular necrosis or other conditions characterized by the osteonecrosis of bones. The other study was to develop a suitable biodegradable thermosensitive hydrogel system as a carrier for bone morphogenetic protein (BMP)-2 delivery in the treatment of critical-sized femoral defects. The BMP-2 release from BOX hydrogel exhibited a near-linear release profile in vitro. In animal experiments, treatment of critical-sized bony defects with 25 wt% BOX hydrogel carrying BMP-2 effectively promoted fracture healing during the 12-week trial period and higher concentrations of BMP-2 treatment correlated with better bone quality. Most importantly, clinical outcome and bone healing in the BOX-hydrogel group with 20 μg/mL BMP-2 were nearly equivalent to those in the autograft group in a 12-week treatment course.
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Wang, Pei-Ting, and 王姵婷. "Gold-BSA nano composite structure analysis and application." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/30323656495179683072.
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碩士國立臺灣師範大學
化學系
103
To assay any possible influences of denaturation on the structure and biochemical functions of proteins, we synthesized artificial cells from AuCl4- and bovine serum albumin (BSA). Results showed that the resulting particles (denoted Au@BSA) were spherical in shape, with a gold core surrounded by a 20-nm BSA layer. When the Au@BSA was exposed to 1 M sodium hydroxide solutions, the interaction force between the cell’s wall and the probe of the atomic force microscope (AFM) increased with time, and the conductivity of the surface of the cell increased as well. After five minutes, both tended to their maximum values. The Au@BSA particles showed similar denaturation symptoms as immersed in 1 M hydrochloric acid. The Au@BSA particles also showed responses to oxidants like and NaClO and hydrogen peroxide. As exposed to NaClO, the BSA layer was badly corroded, and the core became fragile. Despite this, the sensitivty to H2O2 rendered Au@BSA functioning as a fluorescent H2O2 probe and even as a probe for glucose if horseradish peroxidase (HRP) and glucose oxidase (GOx) were incorporated. Besides, the Au@BSA particles also showed potential in the fabricating nanocircuitry. Au@BSA-based filed-effect transistor was thus developed, which could be useful for the detection of biologically important substances. Key words:Gold Nanoparticle, Artificial Cell, Atomic Force Microscopy, Denaturation, Force Curve
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Rocha, Nuno Miguel Marques Pereiro. "Interactions in composite materials : influence on application properties." Doctoral thesis, 2010. http://hdl.handle.net/10316/14552.
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Zeng, Jian-Jia, and 曾建嘉. "Preparation and Application of Gold Dendritic Nanoforests Composite." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/76ku5s.
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碩士國立聯合大學
化學工程學系碩士班
107
In this study, the successful preparation of gold dendritic nanoforests (Au DNFs)/titanium nitride (TiN)/silicon (Si) composite was proposed for visible-light photodegradation. A high-power impulse magnetron sputtering system was used to coat TiN films on silicon wafers, and a fluoride-assisted galvanic replacement reaction was applied to deposit Au DNFs on TiN/Si substrates. Scanning electron microscope images, energy-dispersive X-ray spectroscopy patterns and X-ray diffraction patterns of TiN/Si, Au DNFs/Si, and Au DNFs/TiN/Si samples verified that this synthesis process was accurately controlled. Under the synthetic reaction conditions in this study, the thickness of the Au DNFs increased linearly to 5.10±0.20 µm within 15 min of the reaction. It is proved that the synthesis procedure was a simple and rapid approach for preparing Au DNFs/TiN/Si composites. The highest optical reflectivity of Au DNFs/Si and Au DNFs/TiN/Si was about 10%, because the broadband localized surface plasmon resonances of Au DNFs caused broadband spectral absorbance. In photocatalytic performance, Au DNFs/TiN/Si had a first order reaction rate constant rate of 13.1×10-3 min-1 for p-nitrophenol under visible light irradiation, and reduced the 90.66±1.41％ concentration of 2.5×10-5 M p-nitrophenol solution in 180 minutes. In terms of antibacterial properties, Au NPs can achieve a bacteriostatic ability of 99±0.16% under visible light, while the Au DNFs had a bacteriostatic ability of 42.32±9.24%.
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Yeh, Tzu-Hao, and 葉子豪. "Application of Polyaniline Composite Filter in Water Antibacteria." Thesis, 2017. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22105CYCU5404023%22.&searchmode=basic.
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碩士中原大學
環境工程學系
105
According to the data, the average annual freshwater water consumption in Taiwan''s aquaculture industry is 68 million tons per year, indicating that the aquaculture industry needs a large amount of fresh water. It is not easy to obtain fresh water resources because of the long shortage of water resources caused by terrain factors in Taiwan. Therefore, how to reuse water resources has become an important subject. For Taiwan, high-density aquaculture fisheries have a high degree of cleanliness requirements for water, and most farms have a very good water treatment and recovery system, but their equipment systems are extremely costly and therefore inexpensive Equipment is a popular research project in recent years. Polyaniline structural characteristics cover a wide range of physical, chemical, magnetic, electrical and other aspects of application value, in recent years, many studies have pointed out that polyaniline can effectively inhibit bacteria, mold and fungi. In this study, dodecyl benzene sulfonic acid and titanium dioxide doped polyaniline were used to study the antibacterial effect of water system. The research included the identification of polyaniline composite material and composite filter, and composite materials and filter materials used in the bottle of antibacterial experiments and the actual water sample antibacterial, record the results and analyze the data. The results showed that the antimicrobial effect of polyaniline powder 5g / L in Escherichia coli (concentration: 106 CFU / L) was 30%, and the antibacterial rate was 100%. Under the same conditions, the antibacterial rate of Staphylococcus aureus was 80%. Polyaniline composite filter in the bottle cup antibacterial test, E. coli and Staphylococcus aureus in 30 minutes to reach the antibacterial rate of 99.99% or more. In the antibacterial experiment of the filter material, the antibacterial rate was 100% after the contact with the effluent (2 * 106 CFU / L) of the sewage plant (the number of raw bacteria: 8.5 * 107 CFU / L), reached an antibacterial rate of 100% after one day of reaction, demonstrating that the composite filter has the potential for antibacterial activity in the solid water sample.
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Lai, Bo-hung, and 賴柏宏. "Fabrication and biomedical application of LaB6 composite nanoparticles." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73489530504228226571.
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碩士國立成功大學
化學工程學系碩博士班
97
This thesis concerns the fabrication of lanthanum hexaboride nanoparticles (LaB6 NPs), silica-coated LaB6 nanoparticles (LaB6@SiO2 NPs) and thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted LaB6 nanoparticles. These composite nanoparticles can be used as novel nanocarriers for biomedicine and the materials for thermotherapy. LaB6 NPs were obtained by a bead milling process. Their morphology, structure, and optical property were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-VIS-NIR spectrophotometer. It was found that the LaB6 NPs have a cubic structure with a mean diameter of 65 nm. Also, they showed a significant absorption in near infrared (NIR) region owing to the free electron plasmon resonance and exhibited an excellent photothermal conversion property under the irradiation of a NIR laser. LaB6@SiO2 NPs were prepared by the sol-gel coating of SiO2 on the surface LaB6 NPs. The thickness of SiO2 shells was tuned by varying the concentration of precursor TEOS. By TEM analysis, the thickness of SiO2 shells varied from 10 to 40nm with increasing the TEOS. By analyses of HRTEM EDS, FTIR and Zeta potential, the core-shell structure has been demonstrated. From UV-VIS-NIR spectra, LaB6@SiO2 NPs still showed a significant absorption in NIR region as LaB6 NPs did. Also, their excellent photothermal conversion property under the irradiation of an NIR laser was retained. Thermoresponsive PNIPAAm-grafted LaB6 NPs (i.e., LaB6 microgels) were prepared by the following two steps. Firstly, the surface of LaB6@SiO2 NPs were modified by 3-(trimethoxysilyl)propyl methacrylate (MPS) to generate C=C bonds on the particle surface. Secondly, PNIPAAm was grafted onto the surface of LaB6@SiO2 NPs to yield the LaB6@SiO2 NPs-impregnated microgels via the radical copolymerization. From the analyses of TEM and TGA, it was found that LaB6 microgels had a mean diameter of 570nm and contained about 20 wt% LaB6@SO2 NPs. By FTIR and Zeta potential analyses, the grafting on the surface of LaB6@SiO2 NPs was confirmed. Furthermore, the UV-VIS-NIR spectra revealed that the LaB6 microgels had stronger absorption in NIR region than PNIPAAm microgels. Also, they exhibited photothermal conversion property under the irradiation of a NIR laser. For the use of LaB6 microgels as the carrier for drug release, isoniazid (INH) was adsorbed in the PNIPAAm shells. The INH release rate was faster above the lower critical solution temperature (LCST) of the LaB6 microgels than below the LCST. When the temperature changed across the LCST, reversible and thermoresponsive release behavior was observed. By the exposure to a NIR laser, the temperature of LaB6 microgels increased and led to the drug release.
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You, Min-Sheng, and 游閔盛. "The growth and application of nanodiamond composite films." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/48793225612275827151.
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碩士國立成功大學
化學工程學系碩博士班
94
Abstract This subject is divided into two parts. The first is fabrication of Nano-diamond films via CH4/H2 as gas source in a hot-filament chemical vapor deposition reactor. The growth rate、grain size、film quality are analysis by SEM, XRD, and RAMAN. The second is fabrication of nanodiamond/SiC nanocomposite. By carefully controlling the gas contents of HMDSO, various nanocomposite films(61Gpa~31Gpa) were synthesized. And fracture toughness were also enhanced via introducing 0.11%Si source in the atmosphere. TEM、XPS analysis also suggest an amorphous SiOx structure in our nanocomposite films.
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Lee, Yung-Hsin, and 李雍信. "Preparation and Application of Microporous TPX Composite Membranes." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/23151283281301803145.
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碩士國立臺灣大學
化學工程學研究所
92
Poly(4-methyl-1-pentene) (TPX) composite membranes for the application of osmotic distillation are prepared in this study. Due to the weak mechanical strength, the preparation and application of the TPX hydrophobic particulate membranes prepared by wet-phase inversion are restricted. The TPX composite membranes are prepared by medium molecular weight TPX and filter paper. The results show that the mechanical strength can be improved successfully. However, the flux of TPX composite membranes is smaller than that of TPX particulate membranes. It shows that the porosity of the substrate is the main factors about the flux. The TPX composite membranes are also compared with commercial PTFE membranes in the application of osmotic distillation. The results show that the fluxes of prepared membranes and commercial PTFE membranes are fairly identical. Finally, comparison between the dead-end filtration by using commercial membranes and the osmotic distillation by using TPX prepared composite membranes was investigated. The results show that the fluxes or retentions of osmotic distillation are better. Because there is no fouling in osmotic distillation, the flux is almost constant.
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Hsueh, Ting-Hsiang, and 薛天翔. "Preparation and application of asymmetric PTFE composite membrane." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/66820623754802384662.
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碩士國立臺灣大學
化學工程學研究所
92
The major aim of the present work is to study methods for making asymmetric PTFE membranes with small pores or without pores. First ,we use the bar coater to coat the PTFE suspended fine powders（particle size is about 0.05μm∼0.5μm） on the PTFE stretched membranes （pore size∼0.5μm）. Then we use the Infrared gold image furnace to heat the surface of the PTFE fin powders. After we finish the total processes for making the asymmetric PTFE membranes, we can use the membranes to apply on the ultra-filtration, nano-filtration, and reverse osmosis and so on. In the processes of making asymmetric PTFE membranes, we fix the type of the coating bar, the coating speed and the quenching temperature; In order to get the optimal conditions for making the asymmetric PTFE membranes, we change the concentration of the PTFE suspended fine powders, the sintering temperature and time or pressure. By using the contact angle meter, SEM, XRD, PMI, DSC or performing the degree of swelling test, we try to understand the properties of the PTFE in many forms. By the contact angle test, we know that the affinity to PTFE of iso-propanol is better; By the SEM, we know the pores on the surface of the sintered membranes are getting smaller and smaller with higher sintered temperature that is above the melt point of the PTFE. Similarly the pores on the surface of the sintered membranes are getting smaller and smaller with more sintered time on the sintered membranes（above the melt point of the PTFE）； By the degree of swelling test, PTFE suspended fine powders have high degree of swelling with organic solutes, but the degree of the swelling for the another PTFE membranes is tiny ; By the XRD, there is no change in the diffraction intensity（2θ∼18°） of the PTFE fine powders after sintering, the stretched PTFE membranes have the highest intensity（2θ∼18°）, but in another diffraction angle （2θ∼41°）, the PTFE fine powders have the highest intensity; By the DSC test, we find the PTFE fine powders have higher melt point and the enthalpy than stretched membrane or sintered membrane. We think the crystal form of the PTFE particles and PTFE membranes are not the same. When we control the sintered condition（500℃ and 1 min）, the PTFE asymmetric membranes is performed in pervaporation in the 90wt% ethanol aqueous solution. , the permeate flux is 100（g╱m2-hr）and the concentration of the permeation is 99wt% water included; we control the condition （425℃ and 1 min）, the membranes are good for the ultra-filtration , the performance is similar as PVDF30,000; When the sintered condition is 425℃ and 3min, the PTFE asymmetric membranes can separate the iso-propanol and ethyl alcohol very well by vapor permeation.
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Chen, KouPing, and 陳克斌. "The Application of Composite Index in Pavement Engineering." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/35893995275736606354.
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碩士淡江大學
土木工程學系
90
Due to the rapid expansion of our domestic highway networks, the demands for pavement maintenance and rehabilitation (M & R) activities are increasing dramatically. Proper selections of M & R activities can extend pavement service life to assure the best use of our limited resources. The major objective of this study is to conduct an in-depth investigation on the application of composite index in pavement engineering. The current practices of domestic pavement M & R activities are first reviewed. The fundamental concepts and evolutions of several structural and functional evaluation indices including Present Serviceability Index (PSI), Maysmeter Output (MO), International Roughness Index (IRI), Pavement Condition Index (PCI), and Pavement Surface Distress Index (PSDI) are investigated. It was found that our domestic practices did not quite follow the global trends of objectivity, simplification, automation, and standardization in using composite indices. Consequently, the relationships, advantages, and deficiencies of both PCI and PSDI are compared in this study. The results indicate that PCI is more preferred due to its measuring ability, replicability, objectivity, and consistency. Toward standardization is also one of the major concerns for using the PCI. Together with the utilization of “uniform sections” and “sampling” concepts, an automated project-level PCI prototype program with well-organized Windows-based graphical user interfaces was developed using Microsoft Visual Basic 6.0 program. Several case studies are conducted to validate the correctness of this prototype program through comparisons of manual calculations and the results of the well-known MicroPaver program. To illustrate the application of the PCI, this program is also implemented in the existing prototype Intelligent Consultant System for Pavement Maintenance And Rehabilitation Technologies for Rigid Pavements (ICSMART-R) and for Flexible Pavements (ICSMART-F), and NETwork Dynamic Segmentation Database (NETDSD) programs for both project level and network level pavement management, respectively. Due to the large amount of data required to determine the PCI, it is not recommended for use in the current domestic network pavement management activities. Several recommendations for carrying out domestic pavement evaluation activities including ascertaining management levels, data requirements, selection of composite indices, personnel and training, automated distress survey and devices, selection of M & R criteria, and pavement performance models are discussed.