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Desenvolvimento de um pós-processador para visualização de resultados de simulação numérica em aqüíferos / Post-processor development for numerical simulationr result visualization in aquifers.Quaresma, José Eduardo 10 September 2004 (has links)
Este trabalho apresenta o desenvolvimento de um programa visualizador de processos em aqüíferos intitulado VPA, como módulo integrante de um pa cote de programas computacionais aplicados ao gerenciamento de recursos hídricos subterrâneos denominado SPA (Simulação de Processos em Aqüí- feros). Esse visualizador foi desenvolvido para sistema operacional SuSE Linux, utilizando como ambientes gráficos o KDE e o GNOME. O ambiente de programação Glade 2 foi escolhido para programação e desenvolvimento do visualiza dor. Este ambiente de programação em C é distribuído nos âmbitos de open source development (GNU), e serve como complemento da interface gráfica com o usuário GUI (Graphic User Interfa ce). Em conjunto com esta linguagem de programa ção foi usado o Data Explorer IBM OpenDX, dis-tribuído também nos termos de open source development, como ferramenta para visualização de simulações em duas e três dimensões. Assim, é possível visualizar os resultados gera dos pela simulação de processos de escoamento de fluidos e transporte de poluentes no subsolo por meio dos módulos de pré e pós-processamento do pacote SPA, na forma de dados binários. O mó dulo desenvolvido representa uma alternativa robusta e econômica para a visualização cientí- fica de processos em aqüíferos. / In this work the development of an aquifer poces ses viewer program called VPA is presented. The program is integrated as a module of a compu- tational package devoted to groundwater resources management named SPA (Simulation for Processes in Aquifers). The program was developed on SuSE Linux operational system utilizing KDE and GNOME graphical environments. The graphic templates for the VPA graphical user interface (GUI)were taken from Glade 2. That graphical library is written in C programming language and is distributed under the open source development license (GNU). Scientific visualization routines from Data Ex- plorer IBM OpenDX, also distributed under GNU license, were gathered to VPA giving to it capabi lity to generate two and three-dimensional gra- phics to numerical results. Thus, VPA constitutes the post-processing tool for reading numerical results from binary files and constructing graphics for fluid flow and pol lutant transport simulation in groundwater in the SPA environment. Such module shows itself an economic and robust alternative in scientific visualization to aquifer processes.
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Análise por meio do método dos elementos finitos de um protetor bucal para atividades esportivas / Analysis through the finite element method of a mouthguard for sports activitiesPoblete, Felipe Andres Ortiz 01 July 2011 (has links)
O uso de protetores bucais na prática de esportes tem ampliado espaço no contexto da prevenção de traumas bucais, bem como apresentado melhoria no desempenho ao longo de sua história. O objetivo deste trabalho foi avaliar o comportamento do complexo buco dento alveolar (lábio, dentes, osso alveolar e ligamento periodontal) por meio do método dos elementos finitos. A metodologia utilizada foi a partir de um modelo em formato esterolitográfico oriundo de uma tomografia computadorizada, o qual foi convertido para um modelo 3D pelo programa Rhinoceros® versão 4.0 sem protetor bucal (controle) e com protetor bucal de 4.0mm de espessura em EVA (copolímero de etileno e acetato de vinila), os quais receberam três cargas diferentes (500, 1000 e 1500N) no programa ANSYS® v12 em regime quaseestático, de caráter elástico linear. Pudemos observar que houve um padrão de comportamento das estruturas envolvidas quanto à dissipação das tensões geradas e ao se comparar o modelo controle com o modelo provido de protetor bucal houve uma absorção das tensões geradas em até 50%, permitindo confirmar a ação do protetor bucal em literatura e tornando o seu uso imperativo durante a prática de esportes, em especial as modalidades de maior contato. / The use of mouthguards in the practice of sports has expanded space in the prevention of oral trauma, and presented performance improvement over its history. The aim of this study was to evaluate the behavior of complex buco dental alveolar (lip, teeth, periodontal ligament and alveolar bone) through the finite element method. The methodology used was based on a sterelithographic model come from a CT scan, which was converted to a 3D model by the program Rhinoceros® version 4.0 without a mouthguard (control) and mouthguard 4.0mm-thick EVA (copolymerof ethylene and vinyl acetate), which received three different loads (500, 1000 and 1500N) in ANSYS® v12 under quasi-static, linear elastic character. We noticed that there was a pattern of behavior of the structures involved and the dissipation of the tensions generated and compare the model with the control model was fitted with a mouthguard absorbs stresses generated by 50%, allowing to confirm the action of the mouthguard in literature and making its use mandatory for participation in sports, in particular the modalities for greater contact.
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Modélisation centrée sur l'homme par la méthode des éléments finis : application à la biomécanique des chocs dans un contexte civil et militaire / Numerical modelling of the human body using Finite Elements Method : application to impact biomechanics and high speed loadings in civil and military contextsAwoukeng Goumtcha, Aristide 01 October 2015 (has links)
Dans le contexte de la biomécanique, les outils numériques constituent des moyens puissants et indispensables dans la compréhension des mécanismes de blessures. Ils permettent de pallier les freins que sont les expérimentations sur l'humain, liés à des raisons d'éthique qui limitent la possibilité d'essais sur des SHPM (Sujets Humain Post Mortem). Le développement de ces outils numériques a conduit à celui de plusieurs mannequins numériques permettant de stimuler diverses sollicitations (civiles ou militaires), nous donnant ainsi accès à des limites de tolérances.En vue d'explorer la réponse dynamique du corps humain soumis à des sollicitations diverses, un modèle de mannequin numérique a été développé au sein du laboratoire. Ce travail de thèse tente donc d'apporter une contribution dans la recherche sur la définition d'un critère de blessure et l'établissement de limites de tolérance du corps humain soumis aux chargements violents de la partie thoracique dans des contextes militaires. / The development of computer science has allowed an increase in the use of numerical approaches such as finite elements method in order to understand physical mechanisms. These numerical tools are often used to extend and complete experimental investigations wich are limited because of high financial cost and ethical issues. Thus, the use of simulation to avoid thes limitations becomes essential in biomechanics investigations. Many numericalmodels of the thorax/abdomen system have been developped over the last two decades. In that framework, a finite element model of the human body, dedicated to high speed loadings, has been developed in the laboratory. In this context, the objective of this Ph.D Thesis is to investigate the consequences of such loadings on the human body and to contribute to the research of injuries criteria and tolerance limit definition.
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[en] VISUALIZATION OF ENGINEERING MODELS THROUGH THE WEB USING VRML / [pt] VISUALIZAÇÃO DE MODELOS DE ENGENHARIA VIA WEB UTILIZANDO VRMLRAUL ADEMAR VALDIVIA PACHECO 31 May 2004 (has links)
[pt] O crescente aumento da disponibilidade de recursos
computacionais para a simulação numérica permite que
cientistas e engenheiros produzam enormes quantidades de
dados. A melhor compreensão destes dados mediante o uso de
técnicas de computação gráfica é conhecido como
visualização cientifica. Este trabalho propõe a
visualização científica de problemas de engenharia usando
uma arquitetura distribuída via WEB. Os dados simulados são
lidos diretamente de um banco de dados e são gerados
arquivos com as informações necessárias para sua
visualização. Geram-se arquivos com dados de pré-
processamento (como nós, elementos, linhas, áreas e
elementos diferenciados por índices) e pós-processamento
(como deformação, deslocamento e tensões, resultados mais
importantes na análise utilizando o método de elementos
finitos). Considerando uma arquitetura distribuída, a
simulação numérica pode ser feita em um computador
(servidor) e a visualização pode ser feita em um outro
computador (cliente), utilizando uma interface simples,
porém robusta para a visualização, como é o caso da WEB. A
utilização do formato VRML facilita a distribuição e
compartilhamento nesta visualização, fazendo assim
independente a plataforma do servidor, que contém o
software de simulação numérica, da plataforma do cliente.
Usando como caso de estudo o software de Análise de
Elementos Finitos ANSYS, os resultados obtidos mostraram-se
satisfatórios e melhor manipuláveis ao se comparar com
resultados visualizados por aquele software. O estudo de
caso pode ser estendido para outros softwares de simulação
da área de mecânica dos sólidos. / [en] The growing increase in computational resources for
numerical simulation allows researchers and engineers to
generate huge amount of data. The understanding of those
data through the use of computer graphics techniques is
known as Scientific Visualization. This work proposes a
Scientific Visualization of engineering problems through
the use of a distributed architecture via Web. The
simulated data are obtained directly from a data base and
the appropriate information is generated to their
visualization.Pre-processing data (such as nodes, elements,
lines, areas etc) and posprocessing data (such as
deformation, stress and strain, from a finite element
analysis) are generated. A distributed architecture is
considered which allows the numerical simulation to be done
in a main computer (server) and the visualization to take
place in another computer (client), by using a simple, but
robust, interface, as is the Web. It is being used the VRML
which provides a natural data distribution and sharing.
Results obtained with the Ansys software, a case study for
a finite element analysis, have proven to be satisfactory
and allowing for easy manipulation when compared with the
results visualized through the mentioned software. The
proposed architecture can be extended to cope with other
solid mechanics software.
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[en] AN AXISYMMETRIC FINITE ELEMENT FORMULATION FOR THE ANALYSIS OF LAMINATED COMPOSITE TUBES / [pt] UMA FORMULAÇÃO DE ELEMENTOS FINITOS AXISSIMÉTRICOS PARA ANÁLISE DE TUBOS LAMINADOS EM MATERIAIS COMPÓSITOSGUILHERME PINTO GUIMARAES 06 November 2006 (has links)
[pt] O emprego de materiais compósitos em estruturas tem ganhado
importância na prática da engenharia devido às suas
características de alta
resistência mecânica, baixa densidade e boa estabilidade a
efeitos térmicos.
Uma das classes de compósitos, a de laminados fibrosos,
pode ser utilizada em
tubulações sujeitas às diversas formas de carregamentos,
como pressão interna
e/ou externa, tração longitudinal, torção, temperatura,
etc. O presente Trabalho
tem por objetivo propor, implementar e testar a formulação
de um modelo de
elemento finito axissimétrico, para a representação do
comportamento de um
tubo laminado por camadas de materiais compósitos
fibrosos. A modelagem
consiste em representar a seção geratriz de um tubo
cilíndrico por um elemento
quadrilateral de quatro nós, com três graus de liberdade
por nó, com os
deslocamentos nodais tomados em relação aos eixos de um
sistema cilíndrico
de coordenadas. Considera-se a perfeita adesão das
camadas, garantindo a
continuidade do campo de deslocamentos. Modelos
constitutivos de materiais
com o comportamento ortotrópico e/ou o transversalmente
isotrópico foram
implementados, obtendo-se respostas para os campos de
deslocamentos, de
deformações e de tensões atuantes. Na validação do modelo
numérico,
considerou-se a comparação de seus resultados com os de
soluções analíticas,
disponíveis na literatura, e aqueles fornecidos por um
programa comercial de
elementos finitos, empregando o modelo com elementos
sólidos. Foram
propostos, para os testes em ambos os casos, exemplos de
laminados com uma
a quatro camadas, com fibras orientadas em diferentes
ângulos. Destas
comparações, verifica-se uma boa convergência das soluções
numéricas obtidas
com o presente modelo, representativo das principais
características cinemáticas
da classe de problemas representada. / [en] The use of composite materials in structures has grown in
the engineering
practice due to its characteristics, of high strength, low
density and a good
stability to thermal effects. A class of composites, the
fibrous laminates, is
generally used in tubes subjected to many types of
loadings as internal and/or
external pressure, traction, torsion, temperatures, etc.
This work has the
objectives to propose, implement and test an axisymmetric
finite element model
formulation that represents the mechanical behavior of a
fibrous laminated
composite tube. Modeling consists in representing the
cylindrical tube generating
section by a quadrilateral element with four nodes and
three degrees-of-freedom
per node, with three nodal displacements defined in a
cylindrical coordinate
system. Layers are considered perfectly bonded together,
assuring continuity
between elements on the displacement fields. Orthotropic
and/or transverse
isotropic constitutive material models were implemented,
allowing solutions for
displacement, strain and stress fields. In the element
numerical model validation,
result comparisons with those from analytical solutions
available on literature and
those from the use of layered solid elements in a
commercial finite element
program were considered. Some examples, considering one to
four layers, with
different fiber angles, were proposed for model testing.
It is noted a good
numerical convergence for the presenting model solutions
which represent the
main kinematic characteristics for this class of problems.
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Maillages non-structurés en modélisation marineLegrand, Sébastien 21 April 2006 (has links)
Cette thèse pose les fondations du modèle « the Second-generation Louvain-la-Neuve Ice-ocean Model » (SLIM) qui est basé sur la méthode des éléments finis et les maillages non-structurés. Ce modèle fait partie d'une seconde génération de modèles numériques de circulation marine ou océanique. Notre travail a principalement porté sur les aspects géométriques liés à l'utilisation des maillages non-structurés. Nous avons implémenté un algorithme de triangulation qui génère automatiquement des maillages anisotropes non-structurés sur le plan et la sphère et nous avons défini des stratégies de raffinement de maillage adaptées aux applications marines. Ces stratégies orchestrent la distribution de la taille et de la forme des éléments du maillage afin d'optimiser la précision et le coût en temps de calcul du nouveau modèle. Nous avons aussi abordé l'interpolation contrainte de champs scalaires et vectoriels d'un premier maillage vers un second. L'utilisation conjointe de ces trois outils combinée avec un estimateur d'erreur a posteriori permettra l'adaptation dynamique de maillages au cours de simulations transitoires. Finalement, nous avons bâti les outils géométriques nécessaires à l'écriture d'une formulation discrète des équations de la dynamique des fluides géophysiques sur la sphère. Basée sur un système de coordonnées curvilignes propre à chaque élément du maillage, cette approche originale ne possède aucune des difficultés mathématiques et numériques liées aux singularités des pôles et auxquelles les modèles de la première génération n'ont pu apporter de solution entièrement satisfaisante.
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Computing Visible-Surface RepresentationsTerzopoulos, Demetri 01 March 1985 (has links)
The low-level interpretation of images provides constraints on 3D surface shape at multiple resolutions, but typically only at scattered locations over the visual field. Subsequent visual processing can be facilitated substantially if the scattered shape constraints are immediately transformed into visible-surface representations that unambiguously specify surface shape at every image point. The required transformation is shown to lead to an ill-posed surface reconstruction problem. A well-posed variational principle formulation is obtained by invoking 'controlled continuity,' a physically nonrestrictive (generic) assumption about surfaces which is nonetheless strong enough to guarantee unique solutions. The variational principle, which admits an appealing physical interpretation, is locally discretized by applying the finite element method to a piecewise, finite element representation of surfaces. This forms the mathematical basis of a unified and general framework for computing visible-surface representations. The computational framework unifies formal solutions to the key problems of (i) integrating multiscale constraints on surface depth and orientation from multiple visual sources, (ii) interpolating these scattered constraints into dense, piecewise smooth surfaces, (iii) discovering surface depth and orientation discontinuities and allowing them to restrict interpolation appropriately, and (iv) overcoming the immense computational burden of fine resolution surface reconstruction. An efficient surface reconstruction algorithm is developed. It exploits multiresolution hierarchies of cooperative relaxation processes and is suitable for implementation on massively parallel networks of simple, locally interconnected processors. The algorithm is evaluated empirically in a diversity of applications.
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Multi-Level Reconstruction of Visual Surfaces: Variational Principles and Finite Element RepresentationsTerzopoulos, Demetri 01 April 1982 (has links)
Computational modules early in the human vision system typically generate sparse information about the shapes of visible surfaces in the scene. Moreover, visual processes such as stereopsis can provide such information at a number of levels spanning a range of resolutions. In this paper, we extend this multi-level structure to encompass the subsequent task of reconstructing full surface descriptions from the sparse information. The mathematical development proceeds in three steps. First, the surface most consistent with the sparse constraints is characterized as the solution to an equilibrium state of a thin flexible plate. Second, local, finite element representations of surfaces are introduced and, by applying the finite element method, the continuous variational principle is transformed into a discrete problem in the form of a large system of linear algebraic equations whose solution is computable by local-support, cooperative mechanisms. Third, to exploit the information available at each level of resolution, a hierarchy of discrete problems is formulated and a highly efficient multi-level algorithm, involving both intra-level relaxation processes and bi-directional inter-level algorithm, involving both intra-level relaxation processes and bidirectional inter-level local interpolation processes is applied to their simultaneous solution.. Examples of the generation of hierarchies of surface representations from stereo constraints are given. Finally, the basic surface approximation problem is revisited in a broader mathematical context whose implications are of relevance to vision.
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Maillages non-structurés en modélisation marineLegrand, Sébastien 21 April 2006 (has links)
Cette thèse pose les fondations du modèle « the Second-generation Louvain-la-Neuve Ice-ocean Model » (SLIM) qui est basé sur la méthode des éléments finis et les maillages non-structurés. Ce modèle fait partie d'une seconde génération de modèles numériques de circulation marine ou océanique. Notre travail a principalement porté sur les aspects géométriques liés à l'utilisation des maillages non-structurés. Nous avons implémenté un algorithme de triangulation qui génère automatiquement des maillages anisotropes non-structurés sur le plan et la sphère et nous avons défini des stratégies de raffinement de maillage adaptées aux applications marines. Ces stratégies orchestrent la distribution de la taille et de la forme des éléments du maillage afin d'optimiser la précision et le coût en temps de calcul du nouveau modèle. Nous avons aussi abordé l'interpolation contrainte de champs scalaires et vectoriels d'un premier maillage vers un second. L'utilisation conjointe de ces trois outils combinée avec un estimateur d'erreur a posteriori permettra l'adaptation dynamique de maillages au cours de simulations transitoires. Finalement, nous avons bâti les outils géométriques nécessaires à l'écriture d'une formulation discrète des équations de la dynamique des fluides géophysiques sur la sphère. Basée sur un système de coordonnées curvilignes propre à chaque élément du maillage, cette approche originale ne possède aucune des difficultés mathématiques et numériques liées aux singularités des pôles et auxquelles les modèles de la première génération n'ont pu apporter de solution entièrement satisfaisante.
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Mechanics of Light Weight Proppants: A Discrete ApproachKulkarni, Mandar 2012 May 1900 (has links)
Proppants are a specific application of granular materials used in oil/gas well stimulation. Employment of hard and soft particle mixtures is one of the many approaches availed by the industry to improve fracture resistance and the stability of the granular pack in the hydraulic fracture. Current industrial practices of proppant characterization involve long term and expensive conductivity tests. However, the mechanics governing the proppant pack response, in particular the effects due to material, shape and size of particles on the pack porosity, stiffness and particle fragmentation are not understood clearly.
The present research embodies analytical and experimental approach to model hard (ceramic) and soft (walnut shell and/or pure aluminum) proppant mixtures by taking into account polydispersity in size, shape and material type of individual particles. The hydraulic fracture condition is represented through confined compression and flowback loads. The particle interactions clearly illustrate changes in pore space as a function of pressure, mixture composition and friction. Single particle compression tests on individual particles are carried out to obtain mechanical properties which are incorporated into the finite element models and are further correlated with the compression/crush response of the mixture. The proppant pack stiffness and particle fragmentation depends strongly on the mixture composition as illustrated in the models and experiments. The flowback models demonstrated that the formation of a stable arch is essential to pack stability. Additional variables that enhance flowback resistance are identified as: addition of softer particles to a pack, softer rock surfaces and higher inter-particle friction. The computational studies also led to the discovery of better, and more efficient pack compositions such as - short and thin pure Al needles/ceramic and the pistachio shells/ceramic mixtures. These analytical results have generated great interest and are engaged in the design of experiments to formulate future proppant pack mixtures at Baker Hughes Pressure Pumping, Tomball, TX.
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