Дисертації з теми "Fiber element method"
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Rezak, Sheila. "Analysis of flexible fiber suspensions using the Lattice Boltzmann method." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24798.
Повний текст джерелаCommittee Co-Chair: Aidun, K. Cyrus; Committee Co-Chair: Ghiaasiaan, Mostafa; Committee Member: Deng, Yulin; Committee Member: Empie, Jeff; Committee Member: Patterson, Tim.
Caselman, Elijah. "Elastic property prediction of short fiber composites using a uniform mesh finite element method." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5036.
Повний текст джерелаThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 19, 2008) Includes bibliographical references.
FERREIRA, CRISTIANE ARANTES. "STUDY OF MECHANICAL BEHAVIOR OF FIBER REINFORCED SOIL THROUGH DISCRETE ELEMENT METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33093@1.
Повний текст джерелаCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Um grande número de novos materiais geotécnicos foi desenvolvido baseado na adição de materiais fibrosos, sendo incorporados como elementos de reforço. A técnica de solo reforçado pode ser representada pela produção e aplicação, não somente de fibra natural, mas também de fibras sintéticas e poliméricas. Estudos anteriores de solos reforçados com fibras de polipropileno têm mostrado melhora significativa das propriedades mecânicas dos solos, tais como o aumento da resistência de pico e resistência pós-pico, ductilidade e tenacidade. Estes resultados mostram um grande potencial deste tipo de fibra, quando utilizado como reforço de solos, por exemplo, em base de fundações superficiais, aterros sobre solos moles e liners de cobertura de aterros sanitários. A partir de ajustes matemáticos para determinar a interação entre solos granulares e observações do comportamento global em macro-escala tornou possível analisar o comportamento de solos granulares reforçados com fibras de uma forma micro-mecânica. A modelagem numérica do comportamento mecânico de solos reforçados com fibras de polipropileno, através de uma análise micro-mecânica, utiliza como ferramenta o Método dos Elementos Discretos (MED), que permite a representação do solo em 2D, a partir de um conjunto de partículas de elementos discretos circulares. O MED descarta a visão clássica do solo como uma forma contínua, proporcionando a possibilidade de modelá-lo como partículas constituintes. Sua formulação baseia-se no equilíbrio de forças e de deslocamentos gerados pelos contatos, os quais são descritos através das leis da física clássica, permitindo o mapeamento dos movimentos de cada partícula. A vantagem da micro-mecânica é a possibilidade de explicitar microestruturas, tais como fibras de polipropileno, responsáveis pela mudança no comportamento do solo. Com base no estudo deste fenômeno, causado pela inserção de fibras de polipropileno em materiais granulares, formulações matemáticas foram propostas com a finalidade de descrever o comportamento de solos reforçados através da implementação do código de elementos discretos (DEMlib). Após a calibração e validação do programa, a influência decorrente da inserção do reforço de fibra ao solo foi analisada, sendo realizadas simulações de ensaios biaxiais em amostras discretas de areia, com e sem o reforço fibroso. O comportamento micro-mecânico de misturas reforçadas permitiu avaliar os efeitos das mudanças no teor de fibras presente na matriz de solo, bem como diferentes rigidezes das fibras. Conclui-se que o estudo realizado pelo Método dos Elementos Discretos identificou a real interação entre as partículas do solo e do reforço em forma de fibra, indicando que as fibras, quando inseridas no solo, podem sofrer deformações plásticas de tração e alongamento até atingir a ruptura, proporcionando a melhora nos parâmetros mecânicos do solo.
A large number of new geotechnical materials was developed based on the addition of fibrous materials being incorporated as reinforcement. The technique of reinforced soil can be represented by the production and application, not only natural fiber, but also synthetic fibers and polymer. Previous studies of soil reinforced with polypropylene fibers have shown significant improvement of mechanical properties of soils, such as increasing the resistance peak and postpeak strength, ductility and toughness. These results show a great potential for this type of fiber, when used as soil reinforcement, for example, based on shallow foundations, embankments over soft soils and liners for landfill cover. From mathematical adjustments to determine the interaction between granular soils and the observation of global macro-scale become possible to analyze the behavior of granular soils reinforced with fibers in a micro-mechanics. The numerical modeling of mechanical behavior of soil reinforced with polypropylene fibers, through a micro-mechanical analysis, the tool uses as the Discrete Element Method (DEM), which allows the representation of the soil in 2D, from a set of particles circular discrete elements. The MED rule out the classical view of soil as a continuous form, providing the ability to model it as a constituent particle. Its formulation is based on the balance of forces and displacements generated by the contacts, which are explained through the laws of classical physics, allowing the mapping of movements of each particle. The advantage of micro- mechanics is the possibility of explicit microstructures, such as polypropylene fibers, responsible for the change in the behavior of the soil. Based on the study of this phenomenon, caused by the insertion of polypropylene fibers in granular materials, mathematical formulations have been proposed in order to describe the behavior of reinforced soils through the implementation of the Code of discrete elements (DEMlib). After calibration and validation program, the influence due to the insertion of fiber reinforcement to the soil was analyzed, and simulations of biaxial tests on discrete samples of sand, with and without the fibrous reinforcement. The micro-mechanical behavior of blends reinforced allowed evaluating the effects of changes in fiber content present in the soil matrix and different rigidities of the fibers. We conclude that the study by the Discrete Element Method identified the actual interaction between the soil particles and the reinforcement in the form of fiber, indicating that the fibers, when inserted into the soil, may undergo plastic deformation and tensile elongation until the rupture, providing an improvement in mechanical parameters of soil.
Boyapati, Siva Kumar. "Finite element analysis of low-profile FRP bridge deck (Prodec 4)." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4945.
Повний текст джерелаTitle from document title page. Document formatted into pages; contains xv, 147 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 145-147).
Suraj, Suraj. "Finite-element modeling of a composite bridge deck." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=4008.
Повний текст джерелаTitle from document title page. Document formatted into pages; contains x, 91 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 85-86).
Middleton, Joseph Ervin. "Elastic property prediction of long fiber composites using a uniform mesh finite element method." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5684.
Повний текст джерелаThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 13, 2009) Includes bibliographical references.
Shao, Susan X. "Application of finite element analysis (FEA) to fiber-reinforced composite of recycled high density polyethelene /." View online, 1993. http://repository.eiu.edu/theses/docs/32211998853201.pdf.
Повний текст джерелаSugden, Frank Daniel. "A NOVEL DUAL MODELING METHOD FOR CHARACTERIZING HUMAN NERVE FIBER ACTIVATION." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1318.
Повний текст джерелаBroyles, Norman S. "Thermoplastic Sizings: Effects on Processing, Mechanical Performance, and Interphase Formation in Pultruded Carbon Fiber/Vinyl-Ester Composites." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/30283.
Повний текст джерелаPh. D.
Jeffers, Ann E. "A Fiber-Based Approach for Modeling Beam-Columns under Fire Loading." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/38692.
Повний текст джерелаPh. D.
Inci, Hasan. "Discrete Fiber Angle And Continuous Fiber Path Optimization In Composite Structures." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614127/index.pdf.
Повний текст джерелаEren, Hakan. "Micromechanical study of interface stress in a fiber-reinforced composite under transverse loading using boundary element method." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA378969.
Повний текст джерелаVelez-Garcia, Gregorio Manuel. "Experimental Evaluation and Simulations of Fiber Orientation in Injection Molding of Polymers Containing Short Glass Fibers." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/27335.
Повний текст джерелаPh. D.
Rahman, Muhammad Ziaur. "Mechanical Performance of Natural / Natural Fiber Reinforced Hybrid Composite Materials Using Finite Element Method Based Micromechanics and Experiments." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6482.
Повний текст джерелаGünnel, Andreas, and Roland Herzog. "Optimal Control Problems in Finite-Strain Elasticity by Inner Pressure and Fiber Tension." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-209295.
Повний текст джерелаGABELMAN, ALAN. "MASS TRANSFER IN DENSE GAS EXTRACTION USING A HOLLOW FIBER MEMBRANE CONTACTOR." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1069799119.
Повний текст джерелаMasghouni, Nejib. "Hybrid Carbon Fiber/ZnO Nanowires Polymeric Composite for Stuctural and Energy Harvesting Applications." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64354.
Повний текст джерелаPh. D.
Saeidi, Farid. "Hygrothermal Fracture Analysis Of Fibrous Composites With Variable Fiber Spacing Using Jk-integral." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615370/index.pdf.
Повний текст джерелаMirzahassanagha, Zeinab, and Eva Malo. "Performance of reinforced concrete bridges strengthened with Carbon Fiber Reinforced Polymers : Case study: Essinge Bridge over Pampaslänken." Thesis, KTH, Bro- och stålbyggnad, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301238.
Повний текст джерелаDetta examensarbete handlar om prestandan för befintliga betongarmerade broar som är externt förstärkta med kolfiberväv. Ett av huvudsyftena med detta arbete är att förstå hur en sådan förstärkningsmetod fungerar när den är applicerad på ett konkavt underlag av en tung betongkonstruktion, såsom en bro. Ett annat viktigt mål är att undersöka beteendet av bindningsskiktet som finns mellan betongen och kolfiberväven. För att uppnå de ovannämnda målen, undersöks en fallstudie bro. Bron över Pampaslänken, som ligger i centrala Stockholm, är den utvalda bron som denna rapport kommer att fokusera på. Att förstärka en befintlig bro externt är en metod som använts för att både bibehålla och förbättra den existerande strukturen. Några exempel som motiverar behovet av att använda en sådan metod är nedbrytning av material eller förändringar i konstruktionens bärförmåga som kan vara ett resultat av ökade trafikbelastningar. När det gäller bron över Pampaslänken, applicerades den externa förstärkningen efter breddningen av bron, vilket ledde till förändringar i strukturens statiska verkningssätt. En ytterligare anledning som gör detta fall intressant att studera är den konkava ytan för vilken förstärkningsmetoden används. För att studera bron över Pampaslänken i detalj, används både en numerisk analys samt en tredimensionell finit elementmodell. Alla numeriska simuleringar är utförda i programvaran Abaqus. Det är viktigt att nämna att för de flesta av simuleringarna appliceras en tvåaxlig fordonslast på 300kN (per axel) på konstruktionen. Dessutom genomförs en kvalitetssäkring av FE-modellen för att verifiera modellens funktionalitet. Några av resultaten från dessa analyser kan jämföras med mätningar från systemet med trådtöjningsgivarna som är placerade på bron. Andra simuleringsresultat kan jämföras med resultat som kommer från en provbelastning som utfördes på bron under maj 2021. Från denna jämförelse kan en överenskommelse hittas i de maximala töjningsvärdena i både betongen och kolfiberväven. På grund av tidsbegränsningar utförs endast linjära elastiska analyser. För att kunna fånga betongens olinjära beteende används den så kallade utvidgade finita elementmetoden (XFEM) som finns i Abaqus, för att modellera in en eventuell spricka i betongen. Mer specifikt placeras sprickan på den delen av farbaneplattan där de maximala normalspänningarna erhålls. Bindningsskiktet som finns mellan betongen och kolfibervävarna modelleras på två olika sätt. I det första sättet skapas ett ’’perfekt’’ band/skikt mellan dessa två material medan i det andra baseras modelleringen på den så kallade Cohesive Zone Method (CZM). Den grundläggande skillnaden mellan dessa två metoder är att när man använder CZM kan ett eventuellt vidhäftningsbrott fångas upp i bindningsskiktet. Dessutom har indata samt olika parametrar som är definierade i CZM, en stor påverkan på de erhållna resultaten. Det kan konstateras att resultaten från fallstudiebron inte kan generaliseras. Däremot har man fått en bättre förståelse för den externa förstärkningsmetoden som implementerats i bron över Pampaslänken. Genom att använda CZM hittas en fordonlast som kan orsaka skador i bindningsskiktet.
Pasa, Dutra Vanessa Fátima. "Um modelo constitutivo para o concreto reforçado com fibras de aço via Teoria da Homogeneização." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/56585.
Повний текст джерелаSteel fiber reinforced concrete (SFRC) is a composite material formed by a cement matrix and a certain amount of randomly dispersed fibers. The main objective of the present work is the formulation of a comprehensive constitutive model for SFRC behavior that relies upon homogenization theory, finite element method (FEM) and taking advantage of experimental data available in the literature as well. The first part of the work is devoted to the assessment of elastic and viscoelastic behavior of SFRC. The study starts with the analysis of linear elastic behavior by implementation of a Mori-Tanaka homogenization scheme, which is based on the Eshelby equivalent inclusion approach. It was found that the micromechanical predictions for the overall stiffness proved to be considerably close to the experimental data, as well as to the finite element solutions obtained from numerical analysis of a representative elementary volume (REV) of SFRC (modeled as a randomly heterogeneous medium). Subsequently, the formulation of the nonaging viscoelastic behavior is carried out by making use of results from Elasticity and the Elastic-Viscoelastic Correspondence Principle. The results are compared to available experimental data and analytical models. The second part of the work focuses on the assessment of macroscopic strength properties of fiber reinforced concrete (FRC). Combining the static approach of limit analysis and the homogenization theory, the macroscopic strength criterion for SFRC was theoretically obtained from the knowledge of the strength properties of the individual constituents (concrete matrix and fibers). Adopting a Drucker-Prager failure condition for the concrete matrix and adopting a simplified geometrical model for fiber orientations and length, an approximate criterion was formulated for the overall strength properties. This formulation was complemented by considering a tensile cut-off condition for the concrete and limited strength properties for the interface. The analytical results were compared to experimental data and also to results obtained from a numeric resolution of the problem of limit analysis stated on the REV the material by means of a specifically devised Finite Element numerical tool in the plasticity context. The comparison allowed investigating the influence of the anisotropy of the employed approximate model, as well as the real fiber morphology on the composite strength properties.
Kulkarni, Mandar Madhukar. "Prediction of Elastic Properties of a Carbon Nanotube Reinforced Fiber Polymeric Composite Material Using Cohesive Zone Modeling." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1235433423.
Повний текст джерелаGolestanian, Hossein. "Modeling of process induced residual stresses and resin flow behavior in resin transfer molded composites with woven fiber mats /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841293.
Повний текст джерелаRoth, Michael Jason 1975. "Flexural and tensile properties of thin, very high-strength, fiber-reinforced concrete panels." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11062007-215816.
Повний текст джерелаAidi, Bilel. "Experimental and Numerical Analysis of Damage in Notched Composites." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82559.
Повний текст джерелаPh. D.
Pasa, Dutra Vanessa Fátima. "Análise do comportamento de estruturas de concreto reforçado com fibras de aço via método dos elementos finitos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10614.
Повний текст джерелаConcrete is a material of great versatility of application in constructions and, since its invention, it has been experimenting significant changes in its form of production and application as well as on its composition. The reason for these continued changes is a permanent search for improvement in concrete’s properties, to widen even more its spectrum of use. In this context, and targeting mainly the improvement of its fragile behavior under tension, the addition of different types of fibers came up as a promising alternative. In this way, disperse fibers and concrete form, together, a composite material that, according to experimental investigations, can bring significant contributions to constructions under a structural standpoint. This is the case of the steel fiber reinforced concrete (SFRC), in whose tests important tensile and biaxial compression strength increases were observed with the increment of the fiber quantity added. Aiming a deeper analysis of this material, the present work has the objective of studying SFRC elements through numerical analyses based on the Finite Element Method. For in such a way, a computational program has been developed in FORTRAN 90/95 language aiming the modeling of the behavior of structures made with this material. On the basis of previous studies, a constitutive model, capable of adequately simulate the behavior of SFRC, was implemented. The representation of the behavior of the materials was carried out through an elastoplastic model and structures under short duration loading conditions were analyzed. Specifically for the determination of the behavior of the concrete with fibers, a variant of the Willam-Warnke rupture surface has been used, which considers the fibers presence through modifications of its tension meridian. Additionally, the concrete cracking was represented in the program by the smeared cracking model, which takes into consideration the contribution of the matrix between cracks. Experimental data available in the literature are compared to the results obtained with the developed computational program. It is observed that the used mathematical model and numerical methodology give results that are quite close to the available experimental data, validating, in this way, the SFRC modeling implemented.
Lepenies, Ingolf G. "Zur hierarchischen und simultanen Multi-Skalen-Analyse von Textilbeton." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231842928873-71702.
Повний текст джерелаThe present work deals with the simulation and the prediction of the effective material behavior of the high performance composite textile reinforced concrete (TRC) subjected to tension. Based on a hierarchical material model within a multi scale approach the load bearing mechanisms of TRC are modeled on three structural scales. Therewith, the mechanical parameters characterizing the composite material can be deduced indirectly by experimentally determined force displacement relations obtained from roving pullout tests. These parameters cannot be obtained by contemporary measuring techniques directly. A micro-meso-macro-prediction model (MMM-PM) for TRC is developed, predicting the macroscopic material behavior by means of simulations of the microscopic and the mesoscopic material behavior. The basis is the qualitative and quantitative identification of the bond properties of the roving-matrix system. The partial impregnation of the rovings and the corresponding varying bond qualities are identified to characterize the bond behavior of rovings in a fine-grained concrete matrix. The huge variety of roving cross-sections is approximated by superellipses on the meso scale. The macroscopic behavior of TRC subjected to tension including multiple cracking of the matrix material is correctly predicted on the basis of the micro- and meso-mechanical models. The calibration and verification of the MMM-PM is performed by simulations of roving pullout tests, whereas a first validation is carried out by a comparison of the numerical predictions with the experimental data from tensile tests. The MMM-PM for TRC is applied to tensile tests of structural members made of TRC. Furthermore, a steel-reinforced concrete plate strengthened by a TRC layer is accurately simulated yielding the macroscopic deflection of the plate, the mesoscopic stress state of the roving and the microscopic stresses of the filaments
Bonnet, Anne-Sophie. "Analyse mathematique de la propagation de modes guides dans les fibres optiques." Paris 6, 1988. http://www.theses.fr/1988PA066093.
Повний текст джерелаRukavina, Tea. "Multi-scale damage model of fiber-reinforced concrete with parameter identification." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2460/document.
Повний текст джерелаIn this thesis, several approaches for modeling fiber-reinforced composites are proposed. The material under consideration is fiber-reinforced concrete, which is composed of a few constituents: concrete, short steel fibers, and the interface between them. The behavior of concrete is described by a damage model with localized failure, fibers are taken to be linear elastic, and the behavior of the interface is modeled with a bond-slip pull-out law. A multi-scale approach for coupling all the constituents is proposed, where the macro-scale computation is carried out using the operator-split solution procedure. This partitioned approach divides the computation in two phases, global and local, where different failure mechanisms are treated separately, which is in accordance with the experimentally observed composite behavior. An inverse model for fiber-reinforced concrete is presented, where the stochastic caracterization of the fibers is known from their distribution inside the domain. Parameter identification is performed by minimizing the error between the computed and measured values. The proposed models are validated through numerical examples
Figueiredo, Marcelo Porto de. "Aplicação do método dos elementos discretos na análise estática e dinâmica de estruturas de concreto reforçado com fibras de aço." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/8297.
Повний текст джерелаWhen submitted to special loading patterns, derived from dynamical actions such as cyclic or impact loads, some alterations in the concrete constitution need to be done, since the material don’t have an adequate behavior under tensile stress. A feasible alternative, in such cases, is to incorporate steel fibers in the concrete matrix. Adding these elements, stress transference mechanisms along the cracks are promoted, increasing the material tenacity. An expressive number of experimental works involving all the kinds of steel fiber reinforced concrete structural elements are available. However, few researches based on numerical methods are found in the literature. In order to contribute with the data collection and the development of the material, the present research work proposes the application of the Discrete Element Method to simulate the composite subjected to static and dynamic loads. Some modifications are made on the method algorithm trying to create the dispersion of fibers in the concrete matrix. The analysis of the boundary conditions used on previous work reveal the importance of using elastic support to don’t overestimate the stiffness of the model. The diagram load versus displacement that came from the static simulations shows that the model is sensible to the addition of fibers: higher proportions of fiber leads to models with higher tenacity. The impact tests also demonstrate sensibility and the crack pattern found on the simulations presented a very good approximation to previous experimental work.
Noor-E-Khuda, Sarkar. "Studies on the out-of-plane behaviour of masonry walls." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/93197/1/Sarkar_Noor-E-Khuda_Thesis.pdf.
Повний текст джерелаFrancescato, Pascal. "Prévision du comportement plastique des matériaux hétérogènes à constituants métalliques : application aux composites à matrice métallique à fibres continues et aux plaques perforées." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10110.
Повний текст джерелаJúnior, Luís Antônio Guimarães Bitencourt. "Desenvolvimento de uma plataforma computacional para análise via método dos elementos finitos de estruturas de concreto armado convencional e reforçado com fibras de aço." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-01092009-154909/.
Повний текст джерелаIn this work a computational platform for the analysis of reinforced concrete structures reinforced or not with steel fibers has been developed. This tool is based on the finite element method and has been obtained by the coupling of FEMOOP, denominated solver, with the pre and post-processor program GiD. The coupling has been possible by programming a set of customization files responsible for the communication between the two base programs. A single graphical interface with particular dialog boxes which are linked to the solver facilities is used to apply the boundary conditions, type of analysis, and material properties in the finite element model. For the geometrical representation of concrete elements, plane isoparametric quadrilateral and triangular finite elements have been implemented, while for the steel reinforcement bars, discrete isoparametric truss finite elements with linear end quadratic interpolation have been used. In order to model the mechanical behavior of concrete materials, a nonlinear isotropic elastic model together with a tension softening linear model has been adapted. Cracks are represented through a rotational smeared crack model. Both Ottosen and 5 parameters Willam-Warnke models can be used as the strength criterion of concrete. A failure model proposed by SEOW and SWADDIWUDHIPONG (2005), based on an adaptation of the Willam-Warnke model where a modification of the tension meridian is introduced, is used to consider the discontinuous steel fibers dispersed into the concrete mass. The post-cracking behavior of the steel fiber reinforced concrete considers the tension model proposed by LIM et. al (1987). The steel rebars have their behavior described by a bilinear elastoplastic model. A perfect bond between concrete and the reinforcing bars is assumed. For the solution of the nonlinear equations the Newton-Raphson method is used. The developed computational platform has been evaluated through a set of numerical simulations of tests performed in conventionally reinforced and steel fiber reinforced concrete beams available on the literature. These simulations confirm the efficiency of the current implementation.
Lepenies, Ingolf G. "Zur hierarchischen und simultanen Multi-Skalen-Analyse von Textilbeton." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23636.
Повний текст джерелаThe present work deals with the simulation and the prediction of the effective material behavior of the high performance composite textile reinforced concrete (TRC) subjected to tension. Based on a hierarchical material model within a multi scale approach the load bearing mechanisms of TRC are modeled on three structural scales. Therewith, the mechanical parameters characterizing the composite material can be deduced indirectly by experimentally determined force displacement relations obtained from roving pullout tests. These parameters cannot be obtained by contemporary measuring techniques directly. A micro-meso-macro-prediction model (MMM-PM) for TRC is developed, predicting the macroscopic material behavior by means of simulations of the microscopic and the mesoscopic material behavior. The basis is the qualitative and quantitative identification of the bond properties of the roving-matrix system. The partial impregnation of the rovings and the corresponding varying bond qualities are identified to characterize the bond behavior of rovings in a fine-grained concrete matrix. The huge variety of roving cross-sections is approximated by superellipses on the meso scale. The macroscopic behavior of TRC subjected to tension including multiple cracking of the matrix material is correctly predicted on the basis of the micro- and meso-mechanical models. The calibration and verification of the MMM-PM is performed by simulations of roving pullout tests, whereas a first validation is carried out by a comparison of the numerical predictions with the experimental data from tensile tests. The MMM-PM for TRC is applied to tensile tests of structural members made of TRC. Furthermore, a steel-reinforced concrete plate strengthened by a TRC layer is accurately simulated yielding the macroscopic deflection of the plate, the mesoscopic stress state of the roving and the microscopic stresses of the filaments.
Garcez, Estela Oliari. "Análise teórico-experimental do comportamento de concretos reforçados com fibras de aço quando submetidos a cargas de impacto." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2005. http://hdl.handle.net/10183/7842.
Повний текст джерелаWhen submitted to special loading patterns, derived from dynamical actions such as cyclic or impact loads, concrete elements need to be reinforced, in order to resist the tensile stresses. A feasible alternative, in such cases, is to incorporate fibers in the concrete matrix. The fibers act as a tensile reinforcement, transforming the fragile cement matrix into a composite with significant post-cracking residual strength. In order to contribute with the data collection about the efficiency of different fiber types, the present research work presents an analysis of the behavior of steel fiber reinforced concretes subjected to impact loads. The work investigates the influences of changes in the shape factor, length and amount of fibers. The effects of these combinations on other basic properties of the composites, such as compression strength, split cylinder tensile strength, Young’s modulus and tenacity is also measured. Additionally, a comparison is made between the experimental results from the impact tests and the estimates obtained from a theoretical model that uses the discrete element method (DEM). This theoretical approach aimed to determine if the model was able to simulate the damage evolution over time generated by the increasing impacts loads, as well as to determine the total energy necessary to crack and break the specimens. The results obtained pointed out that the introduction of steel fibers does not affect the energy for the first crack but increases significantly the tenacity of the composite. Longer fibers, with greater shape factors, tend to be more efficient, provided that the fiber content is sufficiently high. The minimum recommended fiber content, according to the data from this research, may be around 100.000 fibers/m3, for longer fibers (50-60 mm). Or around 400.000 fibers/m3, for shorter fibers, which are not so efficient in terms of anchorage. The impact test method developed was considered adequate, being sensitive to the phenomenon and providing reliable data. The DEM model, however, needs to be refined to be able to deal with fiber concrete composites.
Nakhaei, Mohsen. "Layer-specific multiscale mechanical modeling of arterial structures with evolving fiber configurations." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEM014.
Повний текст джерелаArterial tissues are made of variously organized collagen and elastin networks and exhibit a highly nonlinear anisotropic behavior with the ability to sustain large reversible strains and to undergo a load-induced progressive morphological rearrangement of the microstructure. In the present study motivated by these specificities of arterial mechanics, we developed a detailed multi-scale model of the arterial wall. The framework of finite strain continuum micromechanics was employed in an incremental approach to compute stress, strain, and fiber reorientations. The extensions of Eshelby’s matrix-inclusion problem allowed for deriving analytical expressions for the concentration tensors, which relate the macroscopic strain rate tensor to phase-averaged strain rate and vorticity. The model accounts for the universal patterns across different scales in the two mechanically significant layers of arteries, namely the adventitia and the media. Furthermore, the multi-scale constitutive model was implemented in a non-linear finite element formulation to solve the structural model of the artery. The model was validated against different experimental data sets on arterial samples from different species. The results show that the model is able to estimate the contribution of each component into the macroscopic response of the tissue for different loading and can predict both the macroscopic response and microscopic fiber kinematics accurately. We submit that such model would help in predicting the evolution of the mechanical tissue response overtime during, for instance, remodeling and growth or damage
Malheiros, Silveira Gilliard Nardel 1980. "Modelagem por elementos finitos de dispositivos fotônicos e de RF." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259180.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Esta dissertação aborda a modelagem e análise de Dispositivos Fotônicos e de RF via códigos home-made e comerciais baseados no método dos elementos finitos (MEF) e, em alguns casos, resolução de problemas inversos com auxílio de AG. Primeiramente é feita uma breve revisão sobre elementos finitos e AG, bem como alguns fenômenos eletromagnéticos voltados às aplicações estudadas. Os estudos de problemas fotônicos abordaram dois problemas gerais: Otimização da banda fotônica proibida absoluta em cristais fotônicos bidimensionais e propostas de fibras de cristais fotônicos (PCFs, Photonic Crystal Fibers) voltadas para aplicações não-lineares e compensação de dispersão. Algumas dessas análises envolveram a resolução de problemas inversos via AG; em que foi proposta uma codificação com certa generalização para problemas envolvendo PCF. As propostas envolvendo RF abordaram antenas para etiquetas RFID (Radio Frequency Identification). Foi explorado o comportamento dual-band a partir de uma antena do tipo dipolo modificada.
Abstract: This dissertation addresses the modeling and analysis of photonic and RF devices by home-made and commercial codes based on the finite element method (FEM). In some cases, inverse problems have been solved with the aid of genetic algorithms (GA). In the introduction a brief review of finite elements and GA are presented as well as some electromagnetic phenomena related with the applications here analyzed. Concerning the photonic problems, our studies were restricted to two general problems: Optimization of absolute photonic band gap in two-dimensional photonic crystals and the proposal of photonic crystal fibers (PCFs) aimed for non-linear and dispersion compensation applications. Some of the analysis involved the solution of inverse problems by means of GA, where, a codification with some generalization to problems involving PCFs was proposed. The proposals involving RF antennas for RFID (radio frequency identification) tags included the study of modified dipole antennas with dual-band operation.
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Tiar, Mohamed Amine. "Éléments finis spéciaux pour l’analyse linéaire et non-linéaire géométrique des structures composites à renforts fibreux." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2345/document.
Повний текст джерелаNumerical modeling of composite materials and structures with complex geometry of fiber reinforcement, such as stitched composites, constitutes a major research axis in order to correctly predict their mechanical behavior. Within this context, this study focuses on the development of new linear and nonlinear specific finite elements based on a multiscale numerical approach, called the Projected Fiber Approach (PFA). This numerical approach has the advantage of taking into account the presence of fi bers, long or short and distributed randomly or specifically, within a matrix space without discretizing them. Consequently, the obtained system of equations size is equivalent to that without reinforcement (matrix), which considerably reduces the computational cost. To analyze the linear and geometrically nonlinear behaviors of composite structures, two membrane finite elements, named PFT3 and PFQ4, and a 3D solid finite element, named PFH8, were developed and implemented into the commercial finite element code ABAQUS via the user element subroutine (UEL). Several numerical linear and nonlinear tests are considered to assess the accuracy and efficiency of the proposed composite finite elements, and the obtained results are globally in good agreement with the reference solutions. Moreover, the major interest of the PFA approach is particularly emphasized by studying two 3D complex reinforced composite structures: a stitched sandwich plate and a hollow core sandwich plate reinforced by "8" shape fibers
Villard, Pascal. "Etude du renforcement des sables par des fils continus : modelisation et applications." Nantes, 1988. http://www.theses.fr/1988NANT2017.
Повний текст джерелаFilho, Geraldo Dantas Silvestre. "Comportamento mecânico do poliuretano derivado de óleo de mamona reforçado por fibra de carbono: contribuição para o projeto de hastes de implante de quadril." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-19062002-164939/.
Повний текст джерелаThe polyurethane derived from castor oil has demonstrated excellent biocompatibility and similarity to the physical and chemical properties of the human bone. In order to use this material in the design of hip implant stems, this work investigates its mechanical behavior when reinforced by carbon fibers. A manufacturing methodology for hip implant stems is also proposed and validated. The effects of fiber volume fraction and superficial treatments on the carbon fibers are evaluated in terms of the mechanical properties of the polyurethane and of the composite. Mechanical tests were performed in the manufactured stems to evaluate the strength under quasi-static loading. Computational simulations of the stem and testing devices were also performed by using the Finite Element Method and the commercial package ANSYS®. The results obtained are quite satisfactory which validates the application of the carbon fiber reinforced polyurethane in hip implant stems.
Ghouali, Mohamed Amine. "NNouvel outil-d'aide à la conception de formes optimales : analyse de sensibilité analytique locale : principes, validation et applications." Cachan, Ecole normale supérieure, 1997. http://www.theses.fr/1997DENS0018.
Повний текст джерелаBergström, Per. "Modelling Mechanics of Fibre Network using Discrete Element Method." Licentiate thesis, Mittuniversitetet, Avdelningen för kemiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-34640.
Повний текст джерелаVid tidpunkten för framläggningen av avhandlingen var följande delarbeten opublicerade: delarbete 2 och 3 (manuskript).
At the time of the defence the following papers were unpublished: paper 2 and 3 (manuscript).
Knight, Matthew G. "Numerical modelling of particulate and fibre reinforced composites." Thesis, Brunel University, 2002. http://bura.brunel.ac.uk/handle/2438/7387.
Повний текст джерелаChambard, Thierry. "Contribution à l'homogénéisation en plasticité pour une répartition aléatoire des hétérogénéités." Grenoble 1, 1993. http://www.theses.fr/1993GRE10004.
Повний текст джерелаFan, Xijun. "Numerical study on some rheological problems of fibre suspensions." School of Aerospace, Mechanical & Mechatronic Engineering, 2006. http://hdl.handle.net/2123/1096.
Повний текст джерелаThis thesis deals with numerical investigations on some rheological problems of fibre suspensions: the fibre level simulation of non-dilute fibre suspensions in shear flow; the numerical simulation of complex fibre suspension flows and simulating the particle motion in viscoelastic flows. These are challenging problems in rheology. Two numerical approaches were developed for simulating non-dilute fibre suspensions from the fibre level. The first is based on a model that accounts for full hydrodynamic interactions between fibres, which are approximately calculated as a superposition of the long-range and short-range hydrodynamic interactions. The long-range one is approximated by using slender body theory and includes infinite particle interactions. The short-range one is approximated in terms of the normal lubrication forces between close neighbouring fibres. The second is based on a model that accounts only for short-range interactions, which comprise the lubrication forces and normal contact and friction forces. These two methods were applied to simulate the microstructure evolution and rheological properties of non-dilute fibre suspensions. The Brownian configuration method was combined with the highly stable finite element method to simulate the complex flow of fibre suspensions. The method is stable and robust, and can provide both micro and macro information. It does not require any closure approximations in calculating the fibre stress tensor and is more efficient and variance reduction, compared to CONNFFESSITT, for example. The flow of fibre suspensions past a sphere in a tube and the shear induced fibre migration were successfully simulated using this method The completed double layer boundary element method was extended to viscoelastic flow cases. A point-wise solver was developed to solve the constitutive equation point by point and the fixed least square method was employed to interpolate and differentiate data locally. The method avoids volume meshing and only requires the boundary mesh on particle surfaces and data points in the flow domain. A sphere settling in the Oldroyd-B fluid and a prolate spheroid rotating in shear flow of the Oldroyd-B fluid were simulated. Based on the simulated orbit of a prolate spheroid in shear flow, a constitutive model for the weakly viscoelastic fibre suspensions was proposed and its predictions were compared with some available experimental results. All simulated results are in general agreement with experimental and other numerical results reported in literature. This indicates that these numerical methods are useful tools in rheological research.
Sadek, Mohammad. "Modeling biofibre (hemp) processing using the discrete element method (DEM)." Food & Process Engineering Institute Division of ASABE, 2011. http://hdl.handle.net/1993/18484.
Повний текст джерелаLasota, Tomáš. "Computational Modelling of Mechanical Behaviour of "Elastomer-Steel Fibre" Composite." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-234188.
Повний текст джерелаKulkarni, Raghav Shrikant. "Characterization of carbon fibers: coefficient of thermal expansion and microstructure." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3073.
Повний текст джерелаSirivedin, Suparerk. "Micromechanics of progressive failure in carbon fibre-reinforced composites using finite element method." Thesis, King's College London (University of London), 2001. https://kclpure.kcl.ac.uk/portal/en/theses/micromechanics-of-progressive-failure-in-carbon-fibrereinforced-composites-using-finite-element-method(825de9c4-f644-4b2f-b6d1-95569f46c0a5).html.
Повний текст джерелаKorkees, Feras. "Modelling of water absorption into carbon fibre/epoxy composites." Thesis, Swansea University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678568.
Повний текст джерелаGraziano, Maria. "Updating of Finite Element Models using static and dynamic optical strains with application to damage assessment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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