Projeto, constru����o e teste de equipamento para ensaios de fadiga de risers flex��veis

Apesar da vida em fadiga de risers flex��veis ser de grande import��ncia na explota����o ���off-shore���, os dados dispon��veis s��o bastante restritos. A intera����o entre as suas v��rias camadas, as in��meras combina����es realizadas entre elas para se obter diferentes caracter��sticas e os recentes avan��os em termos de materiais, nos obrigam a estud��-los constantemente. Este trabalho tinha como objetivo principal a constru����o de um equipamento para possibilitar o estudo da vida em fadiga de risers, atrav��s de movimentos de tra����o combinada com flex��o, referentes ao teste ���a��� da classe II da norma API 17B, bem como todos os outros testes da classe I da referida norma. Foram projetadas a estrutura e todos os demais componentes, que posteriormente foram redimensionados pelos resultados obtidos em simula����es num��ricas (elementos finitos). Posteriormente, de posse de todos os componentes, realizou-se a montagem do equipamento, seguida de um teste final, que foi acompanhado por uma an��lise extensom��trica dos principais pontos da estrutura. A conclus��o b��sica deste trabalho foi obtida atrav��s da compara����o das an��lises por elementos finitos e extensom��trica, onde foi constatado que o equipamento estava apto a entrar em opera����o para a realiza����o de ensaios est��ticos ou din��micos, observando-se apenas algumas restri����es comentadas.

Estudo de cargas impulsivas com ��nfase em explos��es : estrat��gias de an��lises utilizando m��todos num��ricos

A avalia����o da solicita����o produzida por explos��es, assim como da resposta de estruturas, s��o temas de muito interesse na engenharia atualmente, tanto pela quantidade crescente de acidentes relacionados com explos��es quanto pelas a����es terroristas muitas vezes vinculadas a estes tipos de a����es. Neste contexto, o presente trabalho tem por objetivo explorar t��cnicas de an��lise tanto na modelagem da excita����o quanto na resposta de estruturas consideradas como alvos. Para isto, s��o utilizadas metodologias de diferentes tipos: implementa����es baseadas em sistema de elementos finitos comerciais como Ansys [2000] e LS-Dyna [2003] e t��cnicas simplificativas que permitem realizar uma avalia����o preliminar. As aplica����es consideradas s��o indicadas a seguir: ��� An��lise da Resposta de Estruturas Laminares Submetidas �� A����o de Cargas Explosivas: determina-se a press��o produzida por explosivos s��lidos a certa dist��ncia do epicentro, atrav��s de m��todos simplificados, determinando a resposta esperada em placas retangulares; ��� Efeito da Press��o Interna em Vasos de Press��o (Extintores de Inc��ndio): comparando resultados num��ricos e experimentais verifica-se a influ��ncia da press��o interna nas propriedades din��micas do sistema; ��� Estudo de Um Vaso Esf��rico de GLP Sob A����o de Uma Carga Explosiva: aplica-se a a����o de uma onda explosiva produzida por um g��s inflam��vel pesado sobre uma estrutura de vaso de press��o esf��rico com fluido e g��s em seu interior, determinando sua resposta, avaliando tamb��m a influ��ncia de diferentes quantidades de l��quido e press��o interna na resposta da estrutura; ��� Modelamento de uma Camada de Solo / Propaga����o das Ondas: verifica-se o comportamento da propaga����o de ondas em um meio el��stico, comparando valores encontrados em testes experimentais. Analisa-se numericamente o efeito da inser����o de uma valeta na atenua����o de tais ondas; ��� Simula����o Num��rica Completa de uma Explos��o: modela-se um semi-espa��o submetido �� a����o de um explosivo s��lido sobre sua superf��cie, avaliando os campos de press��o gerados. Ao final de cada aplica����o s��o apresentadas conclus��es parciais obtidas e as possibilidades de trabalhos futuros vislumbrados. Finalmente, conclui-se que as t��cnicas empregadas para as simula����es s��o extremamente eficientes, considerando conhecidos todos os par��metros envolvidos em cada modelo. Neste ponto �� fundamental o trabalho do engenheiro, utilizando-se de seus conhecimentos t��cnicos para transforma����o do evento real em um modelo num��rico, considerando e selecionando as simplifica����es necess��rias.

Gera����o autom��tica de interfaces com o utilizador: uma abordagem baseada em MDA para a plataforma PHP

Os modelos e as t��cnicas de modela����o s��o, hoje em dia, fundamentais na engenharia de software, devido �� complexidade e sofistica����o dos sistemas de informa����o actuais.A linguagem Unified Modeling Language (UML) [OMG, 2005a] [OMG, 2005b] tornou-se uma norma para modela����o, na engenharia de software e em outras ��reas e dom��nios, mas �� reconhecida a sua falta de suporte para a modela����o da interactividade e da interface com o utilizador [Nunes and Falc��o e Cunha, 2000].Neste trabalho, �� explorada a liga����o entre as ��reas de engenharia de software e de interac����o humano-computador, tendo, para isso, sido escolhido o processo de desenvolvimento Wisdom [Nunes and Falc��o e Cunha, 2000] [Nunes, 2001]. O m��todo Wisdom �� conduzido por casos de utiliza����o essenciais e pelo princ��pio da prototipifica����o evolutiva, focando-se no desenho das interfaces com o utilizador atrav��s da estrutura da apresenta����o, com a nota����o Prot��tipos Abstractos Can��nicos (PAC) [Constantine and Lockwood, 1999] [Constantine, 2003], e do comportamento da interac����o com a nota����o ConcurTaskTrees (CTT) [Patern��, 1999] [Mori, Patern��, et al., 2004] em UML.�� proposto, tamb��m, neste trabalho um novo passo no processo Wisdom, sendo definido um modelo espec��fico, constru��do segundo os requisitos da recomenda����o Model Driven Architecture (MDA) [Soley and OMG, 2000] [OMG, 2003] elaborada pela organiza����o Object Managent Group (OMG). Este modelo espec��fico ser�� o intermedi��rio entre o modelo de desenho e a implementa����o da interface final com o utilizador. Esta proposta alinha o m��todo Wisdom com a recomenda����o MDA, tornando poss��vel que sejam gerados, de forma autom��tica, prot��tipos funcionais de interfaces com o utilizador a partir dos modelos conceptuais de an��lise e desenho.Foi utilizada a ferramenta de modela����o e de metamodela����o MetaSketch [N��brega, Nunes, et al., 2006] para a defini����o e manipula����o dos modelos e elementos propostos. Foram criadas as aplica����es Model2Model e Model2Code para suportar as transforma����es entre modelos e a gera����o de c��digo a partir destes. Para a plataforma de implementa����o foi escolhida a framework Hydra, desenvolvida na linguagem PHP [PHP, 2006], que foi adaptada com alguns conceitos de modo a suportar a abordagem defendida neste trabalho.

T��neis rodovi��rios antigos da Madeira

Este trabalho pretende contribuir para um melhor conhecimento sobre os t��neis rodovi��rios antigos existentes na ilha da Madeira. Para tal foi efetuado um levantamento dos t��neis constru��dos entre as d��cadas de 40 e 80, num total de 28 t��neis. Os primeiros t��neis rodovi��rios constru��dos na d��cada de 40 caracterizam-se por uma geometria retangular ou quadrada. Com passar das d��cadas e com a evolu����o ao n��vel das tecnologias utilizadas, os t��neis evolu��ram para sec����es em arco de maior dimens��o. Constata-se que estes foram escavados em maci��os rochosos com boas caracter��sticas geot��cnicas, pelo que eram constru��dos sem qualquer revestimento, recorrendo-se �� execu����o de revestimentos apenas em zonas pontuais. Para efetuar uma an��lise param��trica bidimensional foi utilizado o m��todo dos elementos finitos, onde foram adotadas sec����es de escava����o e materiais com par��metros de resist��ncia considerados representativos dos t��neis em estudo. Este software permitiu analisar o comportamento do maci��o com o faseamento construtivo utilizado na escava����o destes t��neis. Atrav��s da caracteriza����o realizada verifica-se que os t��neis antigos apresentam-se, em geral, em bom estado de conserva����o, pelo que a grande maioria deles encontram-se em funcionamento e atualmente inseridos em vias alternativas utilizadas essencialmente por turistas.

Pr��-dimensionamento de vigas de bet��o armado de acordo com crit��rios de ductilidade

O dimensionamento de uma estrutura de bet��o armado depende em grande parte do tipo de metodologia de c��lculo utilizado, sendo a an��lise n��o linear a que melhor reflete o comportamento da estrutura. Neste tipo de an��lise �� preciso ter em conta alguns aspetos relativos �� ductilidade como, a abertura de fendas, a forma����o de r��tulas pl��sticas e as rela����es n��o lineares do material. Entende-se por ductilidade a capacidade de deforma����o da estrutura sem perda significativa de resist��ncia ap��s atingida a sua capacidade el��stica. Esta pode ser quantificada atrav��s de diversos indicadores. No caso das vigas �� corrente o uso do ��ndice de ductilidade de flecha, que pode ser ��til no pr��-dimensionamento estrutural pois pode permitir aos projetistas pr��-dimensionar vigas segundo um crit��rio de ductilidade. Assim realizou-se uma pesquisa de maneira a identificar quais os fatores mais importantes na ductilidade de uma viga e atrav��s do programa c��lculo de elementos finitos DIANA 9.4 simularam-se 162 vigas variando a percentagem de armadura mec��nica total, o comprimento do v��o, a altura ��til da sec����o, a redistribui����o de momentos e a classe de bet��o. Observou-se que o aumento da percentagem de armadura mec��nica total origina uma diminui����o no ��ndice de ductilidade de cerca de 25% a cada incremento de 0.1 de percentagem de armadura mec��nica total, a esbelteza provoca um aumento de 5% a cada 5 unidades no bet��o C30 e de 2 a 3% no bet��o C70 e a redistribui����o de momentos provocou um aumento na ductilidade. Os resultados mostram que os fatores que mais influenciam na ductilidade das vigas s��o a percentagem mec��nica de armadura total e a classe de resist��ncia do bet��o, no entanto existem outras que dever��o sofrer maior aprofundamento em trabalhos futuros como a utiliza����o de armadura �� compress��o e os n��veis de confinamento do bet��o.

Otimiza����o e an��lise mec��nica de pastas geopolim��ricas para uso em po��os sujeitos �� inje����o c��clica de vapor

Oil wells subjected to cyclic steam injection present important challenges for the development of well cementing systems, mainly due to tensile stresses caused by thermal gradients during its useful life. Cement sheath failures in wells using conventional high compressive strength systems lead to the use of cement systems that are more flexible and/or ductile, with emphasis on Portland cement systems with latex addition. Recent research efforts have presented geopolymeric systems as alternatives. These cementing systems are based on alkaline activation of amorphous aluminosilicates such as metakaolin or fly ash and display advantageous properties such as high compressive strength, fast setting and thermal stability. Basic geopolymeric formulations can be found in the literature, which meet basic oil industry specifications such as rheology, compressive strength and thickening time. In this work, new geopolymeric formulations were developed, based on metakaolin, potassium silicate, potassium hydroxide, silica fume and mineral fiber, using the state of the art in chemical composition, mixture modeling and additivation to optimize the most relevant properties for oil well cementing. Starting from molar ratios considered ideal in the literature (SiO2/Al2O3 = 3.8 e K2O/Al2O3 = 1.0), a study of dry mixtures was performed,based on the compressive packing model, resulting in an optimal volume of 6% for the added solid material. This material (silica fume and mineral fiber) works both as an additional silica source (in the case of silica fume) and as mechanical reinforcement, especially in the case of mineral fiber, which incremented the tensile strength. The first triaxial mechanical study of this class of materials was performed. For comparison, a mechanical study of conventional latex-based cementing systems was also carried out. Regardless of differences in the failure mode (brittle for geopolymers, ductile for latex-based systems), the superior uniaxial compressive strength (37 MPa for the geopolymeric slurry P5 versus 18 MPa for the conventional slurry P2), similar triaxial behavior (friction angle 21�� for P5 and P2) and lower stifness (in the elastic region 5.1 GPa for P5 versus 6.8 GPa for P2) of the geopolymeric systems allowed them to withstand a similar amount of mechanical energy (155 kJ/m3 for P5 versus 208 kJ/m3 for P2), noting that geopolymers work in the elastic regime, without the microcracking present in the case of latex-based systems. Therefore, the geopolymers studied on this work must be designed for application in the elastic region to avoid brittle failure. Finally, the tensile strength of geopolymers is originally poor (1.3 MPa for the geopolymeric slurry P3) due to its brittle structure. However, after additivation with mineral fiber, the tensile strength became equivalent to that of latex-based systems (2.3 MPa for P5 and 2.1 MPa for P2). The technical viability of conventional and proposed formulations was evaluated for the whole well life, including stresses due to cyclic steam injection. This analysis was performed using finite element-based simulation software. It was verified that conventional slurries are viable up to 204��F (400��C) and geopolymeric slurries are viable above 500��F (260��C)

Comp��sitos Portland-biopol��meros para cimenta����o de po��os de petr��leo

The oil production in mature areas can be improved by advanced recovery techniques. In special, steam injection reduces the viscosity of heavy oils, thus improving its flow to surrounding wells. On the other hand, the usually high temperatures and pressures involved in the process may lead to cement cracking, negatively affecting both the mechanical stability and zonal isolation provided by the cement sheath of the well. The addition of plastic materials to the cement is an alternative to prevent this scenario. Composite slurries consisting of Portland cement and a natural biopolymer were studied. Samples containing different contents of biopolymer dispersed in a Portland cement matrix were prepared and evaluated by mechanical and rheological tests in order to assess their behavior according to API (American Petroleum Institute) guidelines. FEM was also applied to map the stress distribution encountered by the cement at bottom bole. The slurries were prepared according to a factorial experiment plan by varying three parameters, i.e., cement age, contents of biopolymer and water-to-cement ratio. The results revealed that the addition of the biopolymer reduced the volume of free water and the setting time of the slurry. In addition, tensile strength, compressive strength and toughness improved by 30% comparing hardened composites to plain Portland slurries. FEM results suggested that the stresses developed at bottomhole may be 10 to 100 times higher than the strength of the cement as evaluated in the lab by unconfined mechanical testing. An alternative approach is proposed to adapt the testing methodology used to evaluate the mechanical behavior of oilwell cement slurries by simulating the confined conditions encountered at bottornhole

Estudo comparativo de p��s para aerogeradores de grande porte fabricadas em materiais comp��sitos refor��adas com fibra de carbono ou fibra de vidro

The research and development of wind turbine blades are essential to keep pace with worldwide growth in the renewable energy sector. Although currently blades are typically produced using glass fiber reinforced composite materials, the tendency for larger size blades, particularly for offshore applications, has increased the interest on carbon fiber reinforced composites because of the potential for increased stiffness and weight reduction. In this study a model of blade designed for large generators (5 MW) was studied on a small scale. A numerical simulation was performed to determine the aerodynamic loading using a Computational Fluid Dynamics (CFD) software. Two blades were then designed and manufactured using epoxy matrix composites: one reinforced with glass fibers and the other with carbon fibers. For the structural calculations, maximum stress failure criterion was adopted. The blades were manufactured by Vacuum Assisted Resin Transfer Molding (VARTM), typical for this type of component. A weight comparison of the two blades was performed and the weight of the carbon fiber blade was approximately 45% of the weight of the fiberglass reinforced blade. Static bending tests were carried out on the blades for various percentages of the design load and deflections measurements were compared with the values obtained from finite element simulations. A good agreement was observed between the measured and calculated deflections. In summary, the results of this study confirm that the low density combined with high mechanical properties of carbon fibers are particularly attractive for the production of large size wind turbine blades

Modelagem num��rica de estruturas de conten����o atirantadas em areia

A numerical study on the behavior of tied-back retaining walls in sand, using the finite element method (FEM) is presented. The analyses were performed using the software Plaxis 2D, and were focused on the development of horizontal displacements, horizontal stresses, shear forces and bending moments in the structure during the construction process. Emphasis was placed on the evaluation of wall embedment, tie-back horizontal spacing, wall thickness, and free anchor length on wall behavior. A representative soil profile of a specific region at the City of Natal, Brazil, was used in the numerical analyses. New facilities built on this region often include retaining structures of the same type studied herein. Soil behavior was modeled using the Mohr-Coulomb constitutive model, whereas the structural elements were modeled using the linear elastic model. Shear strength parameters of the soil layers were obtained from direct shear test results conducted with samples collected at the studied site. Deformation parameters were obtained from empirical correlations from SPT test results carried out on the studied site. The results of the numerical analyses revealed that the effect of wall embedment on the investigated parameters is virtually negligible. Conversely, the tie-back horizontal spacing plays an important role on the investigated parameters. The results also demonstrated that the wall thickness significantly affects the wall horizontal displacements, and the shear forces and bending moments within the retaining structure. However, wall thickness was not found to influence horizontal stresses in the structure

An��lise num��rica do efeito de fatores influentes da rea����o ��lcali-agregado no desempenho de estruturas de concreto

The aim of this work is the numerical simulation of the mechanical performance of concrete affected by Alkali-Aggregate Reaction or RAA, reported by Stanton in 1940. The RAA has aroused attention in the context of Civil Engineering from the early 80, when they were reported consequences of his swelling effect in concrete structures, including cracking, failure and loss of serviceability. Despite the availability of experimental results the problem formulation still lacks refinement so that your solution remains doubtful. The numerical simulation is important resource for the assessment of damages in structures caused by the reaction, and their recoveries The tasks of support of this work were performed by means of the finite element approach, about orthotropic non-linear formulation, and, thermodynamic model of deformation by RAA. The results obtained revealed that the swelling effect of RAA induced decline of the mechanical performance of concrete by decreasing the margin of safety prior to the material failure. They showed that the temperature influences, exclusively, the kinetics of the reaction, so that the failure was the more precocious the higher the temperature of the solid mass of concrete

Desenvolvimento de antenas de microfita e antenas DRA Broadband

The search for ever smaller device and without loss of performance has been increasingly investigated by researchers involving applied electromagnetics. Antennas using ceramics materials with a high dielectric constant, whether acting as a substract element of patch radiating or as the radiant element are in evidence in current research, that due to the numerous advantages offered, such as: low profile, ability to reduce the its dimensions when compared to other devices, high efficiency of ratiation, suitability the microwave range and/or millimeter wave, low temperature coefficient and low cost. The reason for this high efficiency is that the dielectric losses of ceramics are very low when compared to commercially materials sold used in printed circuit boards, such as fiberglass and phenolite. These characteristics make ceramic devices suitable for operation in the microwave band. Combining the design of patch antennas and/or dielectric resonator antenna (DRA) to certain materials and the method of synthesis of these powders in the manufacture of devices, it s possible choose a material with a dielectric constant appropriate for the design of an antenna with the desired size. The main aim of this work is the design of patch antennas and DRA antennas on synthesis of ceramic powders (synthesis by combustion and polymeric precursors - Pe- chini method) nanostructured with applications in the microwave band. The conventional method of mix oxides was also used to obtain nanometric powders for the preparation of tablets and dielectric resonators. The devices manufactured and studied on high dielectric constant materials make them good candidates to have their small size compared to other devices operating at the same frequency band. The structures analyzed are excited by three different techniques: i) microstrip line, ii) aperture coupling and iii) inductive coupling. The efficiency of these techniques have been investigated experimentally and compared with simulations by Ansoft HFSS, used in the accurate analysis of the electromagnetic behavior of antennas over the finite element method (FEM). In this thesis a literature study on the theory of microstrip antennas and DRA antenna is performed. The same study is performed about the materials and methods of synthesis of ceramic powders, which are used in the manufacture of tablets and dielectric cylinders that make up the devices investigated. The dielectric media which were used to support the analysis of the DRA and/or patch antennas are analyzed using accurate simulations using the finite difference time domain (FDTD) based on the relative electrical permittivity (er) and loss tangent of these means (tand). This work also presents a study on artificial neural networks, showing the network architecture used and their characteristics, as well as the training algorithms that were used in training and modeling some parameters associated with the devices investigated

Desenvolvimento de um ressoador retangular de fenda com m��ltiplas camadas de substrato e com utiliza����o de material PBG para sistema de comunica����o sem fio

In the globalized world modern telecommunications have assumed key role within the company, causing a large increase in demand for the wireless technology of communication, which has been happening in recent years have greatly increased the number of applications using this technology. Due to this demand, new materials are developed to enable new control mechanisms and propagation of electromagnetic waves. The research to develop new technologies for wireless communication presents a multidisciplinary study that covers from the new geometries for passive antennas, active up to the development of materials for devices that improve the performance at the frequency range of operation. Recently, planar antennas have attracted interest due to their characteristics and advantages when compared with other types of antennas. In the area of mobile communications the need for antennas of this type has become increasingly used, due to intensive development, which needs to operate in multifrequency antennas and broadband. The microstrip antennas have narrow bandwidth due to the dielectric losses generated by irradiation. Another limitation is the degradation of the radiation pattern due to the generation of surface waves in the substrate. Some techniques have been developed to minimize this limitation of bandwidth, such as the study of type materials PBG - Photonic Band Gap, to form the dielectric material. This work has as main objective the development project of a slot resonator with multiple layers and use the type PBG substrate, which carried out the optimization from the numerical analysis and then designed the device initially proposed for the band electromagnetic spectrum between 3-9 GHz, which basically includes the band S to X. Was used as the dielectric material RT/Duroid 5870 and RT/Duroid 6010.LM where both are laminated ceramic-filled PTFE dielectric constants 2.33 and 10.2, respectively. Through an experimental investigation was conducted an analysis of the simulated versus measured by observing the behavior of the radiation characteristics from the height variation of the dielectric multilayer substrates. We also used the LTT method resonators structures rectangular slot with multiple layers of material photonic PBG in order to obtain the resonance frequency and the entire theory involving the electromagnetic parameters of the structure under consideration. xviii The analysis developed in this work was performed using the method LTT - Transverse Transmission Line, in the field of Fourier transform that uses a component propagating in the y direction (transverse to the real direction of propagation z), thus treating the general equations of the fields electric and magnetic and function. The PBG theory is applied to obtain the relative permittivity of the polarizations for the sep photonic composite substrates material. The results are obtained with the commercial software Ansoft HFSS, used for accurate analysis of the electromagnetic behavior of the planar device under study through the Finite Element Method (FEM). Numerical computational results are presented in graphical form in two and three dimensions, playing in the parameters of return loss, frequency of radiation and radiation diagram, radiation efficiency and surface current for the device under study, and have as substrates, photonic materials and had been simulated in an appropriate computational tool. With respect to the planar device design study are presented in the simulated and measured results that show good agreement with measurements made. These results are mainly in the identification of resonance modes and determining the characteristics of the designed device, such as resonant frequency, return loss and radiation pattern

An��lise de antenas utilizando substrato cer��mico, zpt, produzido por s��ntese auto propagante para aplica����es em sistemas de micro-ondas

Ceramic substrates have been investigated by researchers around the world and has achieved a high interest in the scientific community, because they had high dielectric constants and excellent performance in the structures employed. Such ceramics result in miniaturized structures with dimensions well reduced and high radiation efficiency. In this work, we have used a new ceramic material called lead zinc titanate in the form of Zn0,8Pb0,2TiO3, capable of being used as a dielectric substrate in the construction of various structures of antennas. The method used in constructing the ceramic combustion synthesis was Self- Sustained High Temperature (SHS - "Self-Propagating High-Temperature Synthesis") which is defined as a process that uses highly exothermic reactions to produce various materials. Once initiated the reaction area in the reaction mixture, the heat generated is sufficient to become self-sustaining combustion in the form of a wave that propagates converting the reaction mixture into the product of interest. Were analyzed aspects of the formation of the composite Zn0,8Pb0,2TiO3 by SHS powders and characterized. The analysis consisted of determining the parameters of the reaction for the formation of the composite, as the ignition temperature and reaction mechanisms. The production of composite Zn0,8Pb0,2TiO3 by SHS performed in the laboratory, was the result of a total control of combustion temperature and after obtaining the powder began the development of ceramics. The product was obtained in the form of regular, alternating layers of porous ceramics and was obtained by uniaxial pressing. 10 The product was characterized by analysis of dilatometry, X-ray diffraction analysis and scanning electron microscopy. One of the contributions typically defined in this work is the development of a new dielectric material, nevertheless presented previously in the literature. Therefore, the structures of the antennas presented in this work consisted of new dielectric ceramics based Zn0,8Pb0,2TiO3 usually used as dielectric substrate. The materials produced were characterized in the microwave range. These are dielectrics with high relative permittivity and low loss tangent. The Ansoft HFSS, commercial program employee, using the finite element method, and was used for analysis of antennas studied in this work

Materiais supercondutores HTS para arranjos de antenas e aplica����o de PBG para micro-ondas

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior

Estudo do efeito de substratos metamateriais em par��metros de antenas de microfita

Microstrip antennas are subject matter in several research fields due to its numerous advantages. The discovery, at 1999, of a new class of materials called metamaterials - usually composed of metallic elements immersed in a dielectric medium, have attracted the attention of the scientific community, due to its electromagnetic properties, especially the ability to use in planar structures, such as microstrip, without interfering with their traditional geometry. The aim of this paper is to analyze the effects of one and bidimensional metamaterial substrates in microstrip antennas, with different configurations of resonance rings, SRR, in the dielectric layer. Fractal geometry is applied to these rings, in seeking to verify a multiband behavior and to reduce the resonance frequency of the antennas. The results are then given by commercial software Ansoft HFSS, used for precise analysis of the electromagnetic behavior of antennas by Finite Element Method (FEM). To reach it, this essay will first perform a literature study on fractal geometry and its generative process. This paper also presents an analysis of microstrip antennas, with emphasis on addressing different types of substrates as part of its electric and magnetic anisotropic behavior. It s performed too an approach on metamaterials and their unique properties