Made available in DSpace on 2014-12-17T14:57:50Z (GMT). No. of bitstreams: 1 RannierMM.pdf: 3580955 bytes, checksum: f892200d861ab62414259c44c459e1b9 (MD5) Previous issue date: 2009-03-30 / The use of polymer based coatings is a promising approach to reduce the corrosion problem in carbon steel pipes used for the transport of oil and gas in the oil industry. However, conventional polymer coatings offer limited properties, which often cannot meet design requirements for this type of application, particularly in regard to use temperature and wear resistance. Polymer nanocomposites are known to exhibit superior properties and, therefore, offer great potential for this type of application. Nevertheless, the degree of enhancement of a particular property is greatly dependent upon the matrix/nanoparticle material system used, the matrix/nanoparticle interfacial bonding and also the state of dispersion of the nanoparticle in the polymer matrix. The objective of the present research is to develop and characterize polymer based nanocomposites to be used as coatings in metallic pipelines for the transportation of oil and natural gas. Epoxy/SiO2 nanocomposites with nanoparticle contents of 2, 4, and 8 wt % were processed using a high-energy mill. Modifications of the SiO2 nanoparticles‟ surfaces with two different silane agents were carried out and their effect on the material properties were investigated. The state of dispersion of the materials processed was studied using Scanning and Transmission Electron Microscopy (SEM and TEM) micrographs. Thermogravimetric analysis (TG) were also conducted to determine the thermal stability of the nanocomposites. In addition, the processed nanocomposites were characterized by dynamic mechanical analysis (DMA) to investigate the effect of nanoparticles content and silane treatment on the viscoelastic properties and on the glass transition temperature. Finally, wear tests of the pin-on-disc type were carried out to determine the effects of the nanoparticles and the silane treatments studied. According to the results, the addition of SiO2 nanoparticles treated with silane increased the thermal stability, the storage modulus and Tg of the epoxy resin and decreased wear rate. This confirms that the interaction between the nanoparticles and the polymer chains plays a critical role on the properties of the nanocomposites / A utiliza??o de pol?mero como revestimento ? algo promissor para redu??o de corros?o interna de dutos de a?o carbono utilizados no transporte de petr?leo e g?s natural na ind?stria petrol?fera. No entanto, os revestimentos polim?ricos convencionais apresentam propriedades limitadas, que muitas vezes n?o podem satisfazer os requisitos necess?rios, particularmente em rela??o ? temperatura empregada e ao desgaste. Nanocomp?sitos polim?ricos s?o conhecidos por apresentarem propriedades superiores e, portanto, apresentam potencial para este tipo de aplica??o. Por?m, o grau de refor?o de uma propriedade particular ? fortemente dependente dos materiais utilizados no sistema matriz/nanopart?culas, da liga??o interfacial e, tamb?m, do estado de dispers?o das nanopart?culas na matriz polim?rica. O objetivo do presente trabalho ? desenvolver e caracterizar nanocomp?sitos polim?ricos para utiliza??o como revestimento de dutos met?licos da ind?stria do petr?leo. Nanocomp?sitos Ep?xi/SiO2 com 2, 4 e 8% em massa de nanopart?culas foram processados usando um moinho de alta energia. Modifica??es nas superf?cies das nanopart?culas de SiO2 foram realizadas com dois tipos diferentes de silano e seus efeitos sobre as propriedades dos materiais foram investigados. O estado de dispers?o do material processado foi estudado usando micrografias de Microscopia Eletr?nica de Varredura e de Transmiss?o (MEV e MET). Foram realizadas an?lises termogravim?tricas (TG) para verificar a estabilidade t?rmica dos nanocomp?sitos. Al?m disso, foram realizadas an?lises din?mico-mec?nicas (DMA) para estudar os efeitos das nanopart?culas e dos tratamentos com silano nas propriedades viscoel?sticas e na temperatura de transi??o v?trea (Tg). Por fim, testes de desgaste do tipo esfera-disco foram realizados para determinar os efeitos da adi??o de nanopart?culas e dos diferentes tipos de tratamento de silaniza??o estudados. De acordo com os resultados, a adi??o nanopart?culas de SiO2 tratadas com silano aumentou a temperatura de in?cio de degrada??o do pol?mero, o m?dulo de armazenamento e a Tg da resina ep?xi, al?m de ter proporcionado uma menor taxa de desgaste. Isto confirma que a intera??o entre as nanopart?culas e as cadeias polim?ricas desempenha um papel cr?tico sobre as propriedades dos nanocomp?sitos

Made available in DSpace on 2014-12-17T14:57:52Z (GMT). No. of bitstreams: 1 JoaoMVBSS_TESE.pdf: 1637052 bytes, checksum: 5b9631c974cd41d9288d624c302d0cfb (MD5) Previous issue date: 2011-12-21 / Metal/ceramic interfaces using zirconia have dominated the industrial applications in the last decade, due to the high mechanical strength and fracture toughness of zirconia, especially at temperatures below 300 ?C. Also noteworthy is the good ionic conductivity in high temperatures of this component. In this work joining between ZrO2 Y-TZP and ZrO2 Mg-PSZ with austenitic stainless steel was studied. These joints were brazed at high-vacuum after mechanical metallization with Ti using filler alloys composed by Ag-Cu and Ag-Cu-Ni. The influence of the metallization, and the affinity between the different groups (ceramic / filler alloys) was evaluated, in order to achieve strong metal/ceramic joints. Evaluation of joints and interfaces, also the characterization of base materials was implemented using various techniques, such as: x-ray diffraction, leak test, three-point flexural test and scanning electron microscopy with chemical analysis. The microstructural analysis revealed physical and chemical bonds in the metal/ceramic interfaces, providing superior leak proof joints and stress cracking, in order to a good joint in all brazed samples. Precipitation zones and reaction layers with eutetic characteristics were observed between the steel and the filler metal / As interfaces metal/cer?micas utilizando zirc?nia t?m dominado as aplica??es industriais na ?ltima d?cada, em virtude da alta resist?ncia mec?nica e tenacidade ? fratura da zirc?nia, especialmente em temperaturas abaixo de 300 ?C. Destaca-se tamb?m a boa condutividade i?nica em temperaturas elevadas deste componente. No presente trabalho, estudou-se as uni?es entre ZrO2 Y-TZP e ZrO2 Mg-PSZ com o a?o inox austen?tico 304. Estas jun??es foram produzidas por brasagem a alto-v?cuo ap?s a metaliza??o mec?nica com Ti utilizandose ligas de adi??o compostas por Ag-Cu e Ag-Cu-Ni. Avaliou-se a influ?ncia da metaliza??o, bem como a afinidade entre os diversos grupos (cer?mica / liga de adi??o) com o intuito de se conseguir a melhor uni?o metal/cer?mica. A avalia??o das uni?es e interfaces, bem como a caracteriza??o dos materiais de base foi feita com recurso de diversas t?cnicas, tais como: difra??o de raios-x, ensaios de estanqueidade, flex?o em 3- pontos e microscopia eletr?nica de varredura com microan?lise por espectroscopia de energia dispersiva de raios-x. A an?lise microestrutural revelou liga??es f?sicas e qu?micas na interface metal/cer?mica, proporcionando boa estanqueidade e tens?o de ruptura e, consequentemente, uma boa uni?o em todas as amostras brasadas. Foram observadas zonas de precipita??o e camadas de rea??o com caracter?sticas eut?ticas entre o a?o e o metal de adi??o

Made available in DSpace on 2014-12-17T14:58:07Z (GMT). No. of bitstreams: 1 SistanleyJLB_DISSERT.pdf: 3362424 bytes, checksum: 30d67bc0b13dba47c7002133ab1bb63d (MD5) Previous issue date: 2011-06-20 / This research presents an approach to the addition of curau? fibers and licuri fibers in a polypropylene resin matrix, such as an alternative proposal to reinforce the polymeric composites. Fiber content of 0 %, 5 %, 10 %, and 20% were analyzed for verification of their mechanical properties comparing them, inclusive with the properties of polypropylene. The grainulated biocomposites had been prepared in an extrusora. The test bodies had been molded by injection and submitted to the mechanical essays uniaxial traction, flexion on three points, impact, in addition to thermal tests (HDT). These biocomposites had been also subjected the essay physicist-chemistry index of fluidity (IF). It was observed that the biocomposites of PP with 20% curau?, obtained bigger increase in the modulus of elasticity and a bigger reduction in the resistance to the impact. In the mechanical behavior, for all the biocomposites, these were increases in values of the limit of drainage and tension of rupture, when tested by uniaxial traction, as they added the fibers. Another important point was the increase of the resistance the flexion. It was also noted that the addition of fibers reduced the thermal degradation of the mixture natural fibers / polypropylene. / Esta pesquisa apresenta uma abordagem da adi??o de fibras de licuri e curau? em uma matriz de resina de polipropileno, essa como uma proposta alternativa de refor?o aos comp?sitos polim?ricos. Teores de fibras de 0 %, 5 %, 10 %, e 20 % foram analisados para verifica??o de suas propriedades mec?nicas comparando-as, inclusive com as propriedades do polipropileno. Os biocomp?sitos granulados foram preparados em uma extrusora. Os corpos de prova foram moldados por inje??o e submetidos aos ensaios mec?nicos de tra??o uniaxial, flex?o em tr?s pontos, impacto, al?m de ensaios t?rmicos (HDT). Estes biocomp?sitos tamb?m foram submetidos a ensaio f?sico-qu?mico de ?ndice de fluidez (IF). Observou-se que os biocomp?sitos de PP com 20% curau? obteve maior aumento no m?dulo de elasticidade, e uma maior diminui??o na resist?ncia ao impacto. No comportamento mec?nico, para todos os biocomp?sitos, houve acr?scimos nos valores do limite de escoamento e tens?o de ruptura quando ensaiados por tra??o uniaxial, ? medida que se adicionavam as fibras. Outro ponto importante foi o aumento da resist?ncia ? flex?o. Verificou-se tamb?m que a adi??o de fibras reduziu a degrada??o t?rmica da mistura fibras naturais / polipropileno.

Made available in DSpace on 2014-12-17T14:58:09Z (GMT). No. of bitstreams: 1 HallyjusADB_DISSERT.pdf: 2542860 bytes, checksum: a76cbfa6200b38f0f8ff5811d0315d59 (MD5) Previous issue date: 2011-02-18 / Composite materials have a wide application in various sectors, such as the medical field in the manufacture of prostheses, in automotive and aerospace. Thus it is essential to the development of new composite and a better understanding in the face of various loading conditions and service. Several structural elements are manufactured in the presence of geometric discontinuity (notch, hole, etc ) in their longitudinal sections and/or cross-cutting, and these affect the mechanical response of these elements. The objective is to study the mechanical response of laminated polymer matrix hybrid composites reinforced with glass fiber/jute in a uniaxial tensile test. The mechanical response takes in account both the influence of the presence of a geometric discontinuity (semicircular notches) and the orientation of fibers in the layers (anisotropy). The semicircular notches are located in longitudinal section (with a reduction in cross section) of the same. In this analysis, the anisotropy is characterized by types of configurations (with different orientations of fibers in the outer layers). A comparative study of mechanical properties with and without the presence of notches is developed. Both configurations consist of four layers of woven jute fiber bidirectional and a central layer of bidirectional woven glass fibers. In addition to the mechanical properties was also studied the characteristics of the fracture developed in each composite laminate. The results showed that in the comparative study, the anisotropy and the presence of semicircular notches directly influences the mechanical behavior of laminates composites, mainly in reducing the tensile strength, and well as the final characteristics of the fracture / Os materiais comp?sitos t?m uma ampla aplica??o nos mais variados setores, como por exemplo, na ?rea m?dica na confec??o de pr?teses, na ind?stria automotiva e no setor aeroespacial. Assim ? essencial o desenvolvimento de novos comp?sitos e uma melhor compreens?o frente ?s mais diversas condi??es de carga e servi?o. V?rios elementos estruturais s?o fabricados na presen?a de descontinuidade geom?trica (entalhe, furo etc.) em suas se??es longitudinais e/ou transversais, e essas prejudicam a resposta mec?nica desses elementos. O objetivo do trabalho ? estudar a resposta mec?nica de laminados comp?sitos h?bridos de matriz polim?rica refor?ado com fibras de vidro/juta em um ensaio de tra??o uniaxial. A resposta mec?nica leva em conta tanto a influ?ncia da presen?a de uma descontinuidade geom?trica (entalhes semicirculares) quanto da orienta??o das fibras nas camadas (anisotropia). Os entalhes semicirculares est?o localizados na se??o longitudinal (com redu??o da se??o transversal) dos mesmos. Nessa an?lise, a anisotropia ? caracterizada por dois tipos de configura??es (com diferentes orienta??es das fibras nas camadas externas). Um estudo comparativo das propriedades mec?nicas com e sem a presen?a dos entalhes ? desenvolvido. As duas configura??es consistem de quatro camadas de tecidos bidirecionais de fibras de juta e uma camada central de tecido bidirecional de fibras de vidro. Al?m das propriedades mec?nicas, tamb?m foi estudada as caracter?sticas da fratura desenvolvidas em cada laminado comp?sito. Os resultados mostraram que, no estudo comparativo, a anisotropia e a presen?a dos entalhes semicirculares influi diretamente no comportamento mec?nico dos laminados comp?sitos, principalmente na redu??o da resist?ncia ? tra??o, e bem como na caracter?stica final da fratura

Made available in DSpace on 2014-12-17T14:58:12Z (GMT). No. of bitstreams: 1 KarilanyDC.pdf: 1404746 bytes, checksum: 75321c91ff10021c5b9665530a1b4f3d (MD5) Previous issue date: 2006-05-19 / The topology optimization problem characterize and determine the optimum distribution of material into the domain. In other words, after the definition of the boundary conditions in a pre-established domain, the problem is how to distribute the material to solve the minimization problem. The objective of this work is to propose a competitive formulation for optimum structural topologies determination in 3D problems and able to provide high-resolution layouts. The procedure combines the Galerkin Finite Elements Method with the optimization method, looking for the best material distribution along the fixed domain of project. The layout topology optimization method is based on the material approach, proposed by Bendsoe & Kikuchi (1988), and considers a homogenized constitutive equation that depends only on the relative density of the material. The finite element used for the approach is a four nodes tetrahedron with a selective integration scheme, which interpolate not only the components of the displacement field but also the relative density field. The proposed procedure consists in the solution of a sequence of layout optimization problems applied to compliance minimization problems and mass minimization problems under local stress constraint. The microstructure used in this procedure was the SIMP (Solid Isotropic Material with Penalty). The approach reduces considerably the computational cost, showing to be efficient and robust. The results provided a well defined structural layout, with a sharpness distribution of the material and a boundary condition definition. The layout quality was proporcional to the medium size of the element and a considerable reduction of the project variables was observed due to the tetrahedrycal element / O problema de otimiza??o topol?gica consiste na defini??o do leiaute estrutural pela da distribui??o ?tima de material no espa?o de projeto. Em outras palavras, ap?s serem definidas as condi??es de contorno num dom?nio de projeto pr?-estabelecido, o problema ? como distribuir o material de modo a solucionar o problema de minimiza??o. O objetivo deste trabalho ? propor uma formula??o para a determina??o de topologias estruturais ?timas, que seja competitiva para utiliza??o em problemas 3D e capaz de proporcionar leiautes de alta defini??o. O procedimento combina o M?todo de Elementos Finitos de Galerkin com o m?todo de otimiza??o, buscando a melhor distribui??o de material ao longo do dom?nio fixo de projeto. O m?todo de otimiza??o de leiaute empregado ? baseado na abordagem material, proposta por Bendsoe & Kikuchi (1988), que considera uma equa??o constitutiva homogeneizada dependente apenas da densidade relativa do material. O elemento finito utilizado para a aproxima??o ? o tetra?drico de quatro n?s, com um esquema de integra??o seletiva, que interpola n?o s? as componentes do campo de deslocamento como tamb?m o campo de densidade relativa. O processo proposto consiste na solu??o de uma seq??ncia de problemas de otimiza??o e ? aplicado a problemas de minimiza??o da flexibilidade (atendendo a um limite de volume material) e da massa (satisfazendo um crit?rio de tens?o) em estruturas tridimensionais. A microestrutura utilizada para a descri??o das propriedades materiais ? do tipo SIMP (Solid Isotropic Material with Penalty). A abordagem reduz consideravelmente o custo computacional, mostrando ser efetiva e promissora. Os resultados proporcionaram um leiaute estrutural definido, com n?tida distribui??o do material e defini??o do contorno, com qualidade proporcional ao tamanho m?dio do elemento da malha em quest?o, assim como uma consider?vel redu??o no total de vari?veis de projeto, devido ? utiliza??o do elemento finito empregado

Made available in DSpace on 2014-12-17T14:58:13Z (GMT). No. of bitstreams: 1 AlcioneOG_DISSERT.pdf: 4986234 bytes, checksum: d81c2eeeb91a55690b1f5b9671a9a5e3 (MD5) Previous issue date: 2011-08-26 / Use of natural fibres as a reinforcement material in the manufacture of composites show a series of advantages: availability, biodegradability, low weight and regeneration in relation to synthetic fibres, thus justifying its utilization. In the present research work, composites were developed with chicken feathers (KF), using unsaturated polyester resin as matrix, for diversified applications, mainly in the furniture/timber industry.At present, in Brazil the chicken feathers are used as part of the animal feed, even though this material possesses low aggregated value. The chicken feathers are hollow, light and resistant. After washing with water at room temperature, a part of the chicken feathers were treated with 2% NaOH. Composites were manufactured using treated and untreated chicken feathers with unsaturated orthothalic polyester resin and 1% peroxide as catalyser, obtained in the commerce. Samples with size 150x25x3 mm for mechanical tests were cut by laser in the composite plate. Mechanical analyses were carried out in the Laborat?rio de Metais e Ensaios Mec?nicos UFRN. All the analyses were in accordance with ASTM standards. SEM analyses were also carried out on the samples.In the analyses of the results obtained, it was observed that the composites made with untreated chicken feathers showed better results (Traction 11.406 MPa and 9.107 MPa Bending 34.947 and 20.918 MPa for samples with and without treatment respectively) compared to the composite with treated feathers. Very low values of the water absorption results, evidenced the impermeability characteristic of the feathers. From the SEM images, the structure, fracture and the fibre/matrix adsorption can be evidenced. In the flammability test, it was observed that despite the feathers having sulfur as a constituent, natural inhibitor of flame, no burning support of the composites, because the manufacturing process of the composite / O uso de fibras naturais como refor?o em comp?sitos apresenta uma s?rie de vantagens: abund?ncia, biodegradabilidade, baixo peso e regenerabilidade em rela??o ?s fibras sint?ticas, justificando sua utiliza??o. Na presente pesquisa foram desenvolvidos comp?sitos com penas de frango (KF), utilizando resina de poli?ster n?o-saturado como matriz. Atualmente, no Brasil, as penas de frango s?o utilizadas como parte de ra??o animal, por?m este produto possui um baixo valor agregado. As penas s?o um material oco, leve e resistente. Ap?s a lavagem com ?gua em temperatura ambiente uma parte das penas foi tratada com 2% de NaOH. Foram fabricados dois comp?sitos, um com as penas tratadas e outro sem tratamento, usando o processo de molde fechado por compress?o, utilizando a resina de poli?ster ortoft?lica e 1% de per?xido MEK (per?xido de metil etil cetona) como iniciador, adquiridos no com?rcio local. As amostras com 150x25x3 mm de tamanho para os ensaios mec?nicos foram cortadas a laser na placa do comp?sito. Os ensaios de tra??o e flex?o em tr?s pontos foram realizados no Laborat?rio de Metais e Ensaios Mec?nicos - UFRN. Todas as an?lises estavam de acordo com as normas da ASTM. As amostras resultantes dos ensaios mec?nicas foram avaliadas no MEV. Com base nas observa??es dos resultados nos ensaios mec?nicos, (Tra??o 11,2 Mpa e 8,3 Mpa; Flex?o 34,9 Mpa e 22,9 MPa para as amostras sem e com tratamento respectivamente) observou-se que os comp?sitos refor?ados com as penas sem tratamento apresentaram um melhor comportamento quando foram expostos a carregamentos tanto de tra??o quanto de flex?o. O ensaio de absor??o evidenciou nos valores de absor??o de ?gua, uma das caracter?sticas da prote?na existente nas penas, a queratina, a sua capaciade de impermiabiliza??o a ?gua. Nas imagens do MEV foi poss?vel verificar a estrutura da pena, as regi?es de ruptura do comp?sito e a ades?o fibra/matriz. No ensaio de inflamabilidade, observou-se que apesar das penas terem como constituinte o enxofre, inibidor natural de chama, n?o houve a susten??o da queima nos comp?sitos, devido o processo de fabrica??o do comp?sito

Made available in DSpace on 2014-12-17T14:58:14Z (GMT). No. of bitstreams: 1 JoaoPMS_DISSERT.pdf: 2368005 bytes, checksum: d7875a294c5267dc99db89f3b20a7106 (MD5) Previous issue date: 2012-03-14 / In the present work, three composites with distinct reinforcements (polyester, modal e polyester + modal), all if a unsaturated orthophthalic polyester resin as matrix were used, in order to conduct a comparative study by mechanical tests and water absorption. The fibre mats were prepared in a mat preparatory by immersion developed in the Textile Engineering Laboratory. The composites were manufactured using a closed mould process by compression using an unsaturated orthophthalic polyester resin as matrix and 1% MEK (methyl ethyl ketone peroxide) as an initiator. In each composite twelve samples with the dimensions of 150x25x3 mm were cut randomly for the mechanical analysis (tension x extension, three points bending and water absorption and Scanning Electron Micsroscopy). The mechanical tests were carried out in the Laborat?rio de Metais e Ensaios Mec?nicos UFRN . All the analyses were carried out according to the ASTM norms. The resultant samples from the mechanical analysis were subjected for the Scanning Electron Microscopy analysis. Based on the results obtained, it was observed that the reinforced composite with two fibres (modal + polyester) presented better results in comparison to the other two composites both in the tension/extension as well on the three point bending tests. In the water absorption test, it was possible to observe an equilibrium in the water absorption by the modal and polyester composite, due to the union of the two fibres. In the SEM images, the regions of rupture in the composites as well as the adsorption between the fiber and the matrix could be observed / No presente trabalho foram fabricados tr?s comp?sitos com refor?os distintos (poli?ster, modal e poli?ster + modal), todos com uma matriz de resina de poli?ster ortofit?lico n?o saturado, com o objetivo de realizar um estudo comparativo atrav?s de ensaios mec?nicos e absor??o d ?gua. As mantas de fibras foram preparadas num preparador de manta por imers?o desenvolvido no Laborat?rio de Engenharia T?xtil da UFRN. Os comp?sitos foram fabricados usando o processo de molde fechado por compress?o, utilizando a resina de poli?ster ortoft?lica e 1% de per?xido MEK (per?xido de metil etil cetona) como iniciador. Em cada comp?sito foram cortadas doze amostras aleatoriamente, com as dimens?es 150x25x3 mm, para avalia??o atrav?s de ensaios mec?nicos (resist?ncia ? tra??o e ? flex?o, absor??o d agua e microscopia eletr?nica de varredura). Os ensaios de tra??o e flex?o em tr?s pontos foram realizados no Laborat?rio de Metais e Ensaios Mec?nicos - UFRN. Todas as an?lises estavam de acordo com as normas da ASTM. As amostras resultantes dos ensaios mec?nicas foram avaliadas no MEV. Com base nos resultados dos ensaios mec?nicos, observou-se que o comp?sito refor?ado com as duas fibras em conjunto (poli?ster+modal) apresentou um melhor comportamento quando foram expostos a carregamentos tanto de tra??o quanto de flex?o. No ensaio de absor??o d agua foi poss?vel observar um equilibribio na absor??o de umidade do comp?sito com modal e poli?ster, devido a uni?o das duas fibras. Nas imagens do MEV foi poss?vel ver as regi?es de ruptura do comp?sito e a ades?o entre a fibra e a matriz

Made available in DSpace on 2014-12-17T14:58:19Z (GMT). No. of bitstreams: 1 CamilaCS_DISSERT.pdf: 2789090 bytes, checksum: 9ef229c63f260457515e8c401747ce25 (MD5) Previous issue date: 2012-08-10 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This study aims to evaluate the mechanical properties of polymer matrix composites reinforced with sisal fabric bidirectional tissue (Agave sisalana,) and E-glass fibers, containing the following configuration: a polymer matrix hybrid composite (Polyester Resin orthophalic) reinforced with three (3) layers of glass fibers and alternating-2 (two) layers of bidirectional sisal fabric, and finally a composite of polymer matrix reinforced with five (5) layers of glass fiber mat-type E. For this purpose as first step, the preparation of by sisal, since they are not on the market. The composites were made by manual lamination (Hand lay-up) and evaluated for tensile properties and three point bending both in the dry, and wet conditions aswele as immersed in oil. Macroscopic and microscopic characteristics of the materialsweve awalysed, after the completion of the mechanical tests. After the studies, it was proven that the sisal fiber decreases the tensile stiffness of the material above 50% for both situations studied the tensile strength of the material decreases by approximately 40% for the cases mentioned, and when compared to the specific strength stiffness values drop to 14.6% and 29.02% respectively for the dry state only. Constants for bending the values were are to approximately 50% to 25% for strength and stiffness of the material for the cases dry, wet and immersed in oil. Under the influence of tension fluids do not interfere in the stiffness of the material for the bending tests, the same does not occur with the resistance, and these values are modified only in the cases stiffness and flexural strength / Este trabalho tem como objetivo avaliar as propriedades mec?nicas de comp?sitos de matriz polim?rica refor?ados com tecidos bidirecionais de sisal (Agave Sisalana,) e fibras de vidro E, contendo estes materiais a seguinte configura??o: um comp?sito h?brido de matriz polim?rica (Resina Poli?ster Ortoft?lica) refor?ado com 3 (tr?s) camadas de fibras de vidro e intercalando as 2 (duas) camadas de tecido bidirecional de sisal, e por fim um comp?sito de matriz polim?rica refor?ado com 5 (cinco) camadas de manta de fibras de vidro do tipo E. Para tanto teve se como primeira etapa a confec??o dos tecidos de sisal, j? que estes n?o se encontram no mercado. Os comp?sitos foram confeccionados de acordo com o processo de lamina??o manual (Hand lay-up) e avaliadas as propriedades de tra??o uniaxial e flex?o em tr?s pontos do material tanto em estado seco, como para o material imerso em ?gua destilada e imerso em petr?leo e as caracter?sticas macrosc?picas e microsc?picas dos materiais ap?s a realiza??o dos ensaios mec?nicos, t5amb?m j? realizados. Ap?s a realiza??o dos estudos foi observado que a fibra de sisal diminui a rigidez do material ? tra??o acima de 50 % para ambas as situa??es estudadas, a resist?ncia ? tra??o do material diminui em aproximadamente 40% para os casos citados, sendo que quando comparado ? resist?ncia e rigidez especificas esses valores caem para 14,6% e 29,02 % respectivamente s? para o estado seco. Quando observados as constantes para flex?o esses valores passam a serem de aproximadamente 50 % para a resist?ncia e 25% para a rigidez do material para os casos secos, ?mido e imerso em petr?leo

Made available in DSpace on 2014-12-17T14:58:20Z (GMT). No. of bitstreams: 1 AnaCMCB_DISSERT.pdf: 5204946 bytes, checksum: 70bedde30acbc8578034105c8c4fc24e (MD5) Previous issue date: 2013-07-25 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The utilization of synthetic fibers for plastic reinforcement is more and more frequent and this growing interest requires that their mechanic behavior under the most variable conditions of structural applications be known. The use of such materials in the open and exposed to the elements is one of them. In this case, it becomes extremely necessary to study their mechanical properties (strength, stiffness) and the mechanism of fracture by which the environment aging them out. In order to do that, the material must be submitted to hot steam and ultraviolet radiation exposure cycles, according to periods of time determined by the norms. This study proposal deals with the investigation of accelerated environmental aging in two laminated polymeric composites reinforced by hybrid woven made up of synthetic fibers. The configurations of the laminated composites are defined as: one laminate reinforced with hybrid woven of glass fibers/E and Kevlar fibers/49 (LHVK) and the other laminate is reinforced with hybrid tissue of glass fibers/E and of carbon fibers AS4 (LHVC). The woven are plane and bidirectional. Both laminates are impregnated with a thermofix resin called Derakane 470-300 Epoxy Vinyl-Ester and they form a total of four layers. The laminates were industrially manufactured and were made through the process of hand-lay-up. Comparative analyses were carried out between their mechanical properties by submitting specimen to uniaxial loading tractions and three-point flexion. The specimen were tested both from their original state, that is, without being environmentally aging out, and after environmental aging. This last state was reached by using the environmental aging chamber / O interesse na utiliza??o dos pl?sticos refor?ados por fibras sint?ticas ? cada vez mais crescente e esse grande interesse na utiliza??o dos mesmos faz com que seja necess?rio o conhecimento do comportamento mec?nico desses materiais sob as mais variadas condi??es de aplica??o estrutural. Dentre estas pode ser destacada a aplica??o desses materiais em situa??es em o elemento encontra-se exposto ? intemp?rie, e nesse caso os estudos das propriedades mec?nicas (resist?ncia, rigidez) al?m do mecanismo fratura frente ao envelhecimento ambiental s?o de extrema necessidade. Para tanto, submeter o material ? per?odos c?clicos de exposi??o ao vapor aquecido e ? de radia??o ultravioleta, por tempo definido em norma, se faz necess?rio. A presente proposta de trabalho de investiga??o consiste no estudo do envelhecimento ambiental acelerado em dois laminados comp?sitos polim?ricos refor?ados por tecidos h?bridos ? base de fibras sint?ticas. As configura??es dos laminados comp?sitos s?o definidas como: um laminado refor?ado com tecido h?brido de fibras de vidro/E e de fibras kevlar/49 (LHVK) e outro laminado refor?ado com tecido h?brido de fibras de vidro/E e de fibras de carbono AS4 (LHVC). Os tecidos s?o dos tipos planos e bidirecionais. Ambos os laminados foram impregnados a base de resina termofixa Derakane 470-300 Ep?xi Vinil-Ester e constitu?dos com quatro camadas no total. Os laminados t?m fabrica??o industrial e foram obtidos atrav?s do processo de lamina??o manual (Hand-lay-up). Foram realizados estudos comparativos entre as propriedades mec?nicas sob a a??o dos carregamentos de tra??o uniaxial e flex?o em tr?s pontos, nas condi??es dos corpos de prova sem o efeito do envelhecimento ambiental (estado original) e sob o efeito desse envelhecimento (estado envelhecido). O envelhecimento ambiental foi acelerado atrav?s do uso da c?mara de envelhecimento

Made available in DSpace on 2014-12-17T14:58:21Z (GMT). No. of bitstreams: 1 FaisyPPS_DISSERT_Capa_ate _pag30.pdf: 3190627 bytes, checksum: 6b8c39ddf6fc3949b555ea3b2beef8a3 (MD5) Previous issue date: 2013-03-15 / The need to build durable structures and resistant to harsh environments enabled the development of high strength concrete, these activities generate a high cement consumption, which implies factor in CO2 emissions. Often the desired strength is not achieved using only the cement composition. This study aims to evaluate the influence of pozzolans with the addition of metakaolin on the physical mechanics of high strength concrete comparing them with the standard formulation. Assays were performed to characterize the aggregates according to NBR 7211, evaluation of cement and coarse aggregate through the trials of petrography (NBR 15577-3/08) and alkali-aggregate reaction (NBR 15577-05/08). Specimens were fabricated according to NBR 5738-1/04 with additions of 0%, 4%, 6%, 8% and 10% of metakaolin for cement mortars CP V in the formulations. For evaluation of the concrete hardened in fresh state and scattering assays were performed and compressive strength in accordance with the NBR 7223/1992 and NBR 5739-8/94 respectively. The results of the characterization of aggregates showed good characteristics regarding size analysis and petrography, as well as potentially innocuous as the alkali-aggregate reaction. As to the test of resistance to compression, all the formulations with the addition of metakaolin showed higher value at 28 days of disruption compared with the standard formulation. These results present an alternative to reduce CO2 emissions, and improvements in the quality and durability of concrete, because the fine particle size of metakaolin provides an optimal compression of the mass directly influencing the strength and rheology of the dough / A necessidade de construir estruturas dur?veis e resistentes a ambientes agressivos proporcionou o desenvolvimento do concreto de alta resist?ncia, tais atividades geram um alto consumo de cimento, fator que implica na emiss?o CO2. Muitas vezes a resist?ncia desejada n?o ? atingida utilizando apenas o cimento na composi??o. Este trabalho tem como objetivo avaliar a influ?ncia das pozolanas com a adi??o de metacaulim nas caracter?sticas f?sico mec?nicas do concreto de alta resist?ncia comparando-as com a formula??o padr?o. Foram realizados ensaios de caracteriza??o dos agregados de acordo com a norma NBR 7211, avalia??o do cimento e agregado gra?do atrav?s dos ensaios de petrografia (NBR 15577 - 3/08) e rea??o alcali-agregado (NBR 15577-05/08). Foram confeccionados corpos de prova de acordo com a norma NBR 5738-1/04 com adi??es de 0%, 4%, 6%, 8% e 10% de metacaulim em substitui??o ao cimento CP V nas formula??es. Para avalia??o do concreto no estado fresco e endurecido foram realizados ensaios de espalhamento e resist?ncia ? compress?o de acordo com as normas NBR 7223/1992 e NBR 5739-8/94 respectivamente. Os resultados da caracteriza??o dos agregados apresentaram boas caracter?sticas quanto ? an?lise granulom?trica e petrografia, bem como potencialmente in?cuos quanto ? rea??o alcali-agregado. Quanto ao ensaio de resist?ncia ? compress?o, todas as formula??es com adi??o de metacaulim apresentaram valor superior aos 28 dias de ruptura quando comparadas com a formula??o padr?o. Estes resultados apresentam uma alternativa de redu??o da emiss?o de CO2, al?m de melhorias na qualidade e durabilidade do concreto, pois a fina granulometria do metacaulim proporciona uma ?tima compacta??o da massa influenciando diretamente na resist?ncia mec?nica e reologia da massa