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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Property-microstructural relationships in GFRP

Guild, Felicity Jean January 1978 (has links)
This work consists of an investigation into the microstructure and mechanical behaviour of glass fibre reinforced polyester resin beams. The volume fraction occupied by glass fibres was 20-30%, which is that typically used in boat building. The beams tested were all unidirectional, with fibres oriented parallel or perpendicular to the long axis of the beam. Various techniques have been developed which may be applicable to other composite materials. The microstructure of the beams was investigated by observation of cross-sections using a Quantimet 720 Image Analysing Computer. Volume fractions and the distribution. of fibre cross-sectional areas were measured. Methods have been developed for the quantitative definition of the microstructure, in terms of the fibre arrangement. Cracks were grown in four-point flexural loading while monitoring acoustic emission. The acoustic emission circuit was built in the laboratory, and designed to monitor fibre failures only, one count being associated with one fibre failure. The processes of crack growth were further investigated by observation of fracture surfaces using a scanning electron microscope and measurement of crack profiles. The factors controlling the processes of crack growth have been elucidated. The material condition was monitored by specific damping capacity measurements. A free-free rig with excitation at the ends of the beam was developed. In addition measurements were made using a cantilever rig. Simple analyses involving the solution of the classical wave equation were carried out; a receptance analysis was also developed which allows the undamaged and cracked portions of the beam to be separated in the analysis. Invisible cracks, which had been indicated by acoustic emission, were successfully detected in both rigs. The correlation between recorded acoustic emissions and specific damping capacity measurements supports the validity of both techniques. Some correlation between properties and measured microstructures has been obtained here. These quantitative methods for the measurement of the microstructure of composite materials should prove very useful in a wide range of applications.
2

Etude du mécanisme de dispersion de charge dans une résine polyester : Synthèse de nouveaux dispersants / Study of filler dispersion mechanism in polyester resin : Synthesis of new dispersants

Schuller, Anne-Sophie 28 September 2009 (has links)
Afin d'optimiser les propriétés d'un composite polymère chargé, il est possible de procéder à un greffage de la charge afin de la rendre compatible avec le milieu continu dans laquelle elle est dispersée. Le sujet de recherche consiste à étudier et optimiser le mécanisme de greffage de molécules organiques à la surface de charges minérales.Développé il y a quelques années par la société GTI Process (groupe Mader), le "giral" est une formulation qui permet d'une part d'obtenir une bonne dispersion entre une charge et une matrice polymère et d'autre part d'augmenter les propriétés mécaniques du matériau composite final. Il se compose d'un silane, d'un acide méthacrylique et d'un dispersant. Toutefois, le mécanisme existant lors de l'ajout de giral dans une formulation charge/résine n'a pas été identifié. Nous nous sommes proposé de le comprendre. Après avoir identifié les interactions entre la surface de la silice et les constituants du giral, il nous a paru intéressant de faire évoluer la formulation du dispersant.Dans un premier temps, ce mécanisme a été étudié sur une charge témoin bien maîtrisée : la silice.La silice retenue a l'avantage de posséder une surface spécifique importante. Des analyses thermogravimétrique et infrarouge ont été réalisées sur différents échantillons (synthétisés à partir de silice et d'un ou plusieurs constituants du giral) afin de déterminer les espèces adsorbées ou greffées à la surface de la silice. Des analyses RMN du solide 13C et 29Si ont également été réalisées dans le but de déterminer les liaisons mises en jeu. En parallèle, des études en CGI (Chromatographie Gazeuse Inverse) ont été menées.Dans un second temps, des nouvelles structures ont été développées pour améliorer le dispersant contenu dans la formulation du Giral puis la formulation en synthétisant un seul composé qui regroupe toutes les fonctionnalités requises pour disperser la silice dans une résine polyester. De plus, ces nouvelles structures vont permettre d’augmenter les propriétés mécaniques du matériau composite final. Tous les composés synthétisés, dans ce travail, ont un squelette polymère qui est la polycaprolactone. L’architecture, la composition, la taille et la structure de ces polymères ont été optimisées suivant la charge à disperser. Nous avons ainsi synthétisé une large gamme de dispersants modèles fonctionnalisés et étudié leur comportement dans l'application. D'autre part, seules les méthodes de synthèse en masse, plus adaptées pour une production industrielle, ont été retenues. Ces polymères ont tout d'abord été synthétisés en laboratoire puis dans le milieu industriel. Une fois les polymères synthétisés, plusieurs essais ont été réalisés pour connaître leur influence au niveau des propriétés mécaniques du matériau composite final, déterminer les structures les plus adaptées pour répondre aux contraintes mécaniques, et connaître les quantités nécessaires pour obtenir les meilleurs résultats. Des mesures de viscosité et des essais mécaniques (essais de traction et de flexion 3 points) ont été réalisés. L'utilisation de ces composés développés au cours de ce travail de thèse ont permis de diminuer la viscosité d’une résine polyester chargée et ainsi de pouvoir augmenter le taux de charge. De plus, les faciès de rupture ont été observés par microscopie électronique à balayage afin d'observer la cohésion entre les charges et la matrice polymère du composite. La rupture apparaît au niveau de la charge et du polymère. L'efficacité de ces nouvelles structures dans l’application s'est avérée comparable, voire meilleure par rapport au dispersant de référence et au giral. / To increase the properties of a composite based with polymer and tiller, it is possible to modify the tiller surface to make it compatible with the polymer in which it is dispersed. The aim is to study and optimize the mechanism of organic molecules grafting on mineral fillers surface. Developed several years ago by GTI Process (Mader group), the "giral" i s a formulation that allows a good dispersion between the tiller and the polymer matrix and also an increase of the final composite material mechanical properties. "Giral" is composed of a silane, a methacrylic acid and a dispersant. However, its mechanism with a mixture based on tiller and pol yester resin has not been identified, we proposed to understand it. After identifying the interaction between the surface of silica and "giral" components, it seemed interesting to modify the dispersant. In a first part, the "giral" mechanism has been studied on silica which is a well-known tiller. Silica used has a high specific surface area. Thermogravimetric and infrared analysis have been performed on different samples (synthesized from silica modified by one or more "giral"components) to determine the adsorbed or grafted species on silica surface. NMR analyses of 13C and 29 Si solid and Inverse gas chromatography studies were also conducted. In a second part, new structures have been developed to improve the dispersant in the "giral" formulation and the formulation itself by synthesizing a single compound that includes all the features required for the dispersion of silica in polyester resin. Moreover, these new structures will help to increase the mechanical properties of the final composite material. All compounds synthesized in this work, have a polymer backbone which is polycaprolactone. The architecture, composition, size and structure of these polymers were optimized according to the tiller used. We have synthesized functionalized dispersants and studied their behavior in the application. On the other hand, only syntheses by mass, more suitable for industrial production, were selected. These polymers have been first synthesized in the laboratory and then in industry. Once the polymers synthesized several tests were done to determine their influence in the final composite material mechanical properties, the most appropriate structures to mechanical stress, and the amounts required for best results. Viscosity measurements and mechanical tests were done. These new dispersants developed have reduced the viscosity of the mixture based on polyester resin and tiller, and thus can increase the tiller rate. Furthermore, the fracture surfaces were observed by scanning electron microscopy to observe cohesion between the tiller and the polymer matrix. The effectiveness of these new structures in the application are comparable or even better to the "giral" formulation.
3

Technologická analýza využitelnosti nových typů termosetických materiálů pro konstrukci světlometů / Technological analysis of the usability of new thermosetting materials for the construction of headlamps

Rašner, Martin January 2019 (has links)
The diploma thesis presents the usability of a new thermosetting material BMC for the construction of a car headlight. In the theoretical part there are described headlights, basic characteristics and properties of plastics focussing on polymer composite materials and material testing. The practical part deals with the processing of test samples for mechanical testing by compression moulding and also with the production of real samples of reflectors and carrier frames by injection moulding. The evaluation is based on comparison of the results of the performed tests of alternative material and the currently used BMC TETRADUR TD 492/2 in HELLA Autotechnik Nova s.r.o. Basic physical-mechanical properties such as strength, stiffness, toughness and hardness are tested and monitored. The reflectors and carrier frames are assembled into the headlight and then tested according to legal and customers´ requirements for climate and vibration resistance and photometry.
4

Vliv povrchových úprav skleněných vláken na mechanickou odezvu GF/polyester kompozitu / The influence of surface modification of glass fibers on mechanical response of the GF/polyester composite

Janeček, Pavel January 2008 (has links)
The diploma thesis is aimed at an influence of surface modifications of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber reinforced composites. Glass fibers were used as reinforcements and polyester resin was the matrix. The sample of composite consisted of polymer matrix in a form of cylindrical body placed on bundle of glass fibers. The design of the sample was constructed with respect to results of Finite Element Analysis (FEA). The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface. Untreated glass fibers, fibers with commercial sizing, and fibers modified by deposition of plasma polymer film using Plasma-Enhanced Chemical Vapor Deposition (PECVD) at different deposition conditions were used for fabrication of composite samples. The fibers and composite samples were analyzed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM).
5

Efeito do material da face nas propriedades mecânicas de painéis sanduíche para aplicação rodoviária

Garbin, Daniel Fernando January 2017 (has links)
Painéis sanduíche são largamente utilizadas em diversas aplicações de engenharia e o estudo de suas propriedades é fundamental para a ampliação de sua utilização. Neste trabalho, foram estudados painéis sanduíche com núcleo de poliuretano e faces de fibra de vidro fabricados pelo processo de laminação contínua. Na primeira configuração, as faces do painel foram fabricadas com manta de fibra de vidro e resina poliéster, com 39% de teor de vidro em massa e espessura de 1,9 mm. Na segunda configuração, as faces do painel foram fabricadas com tecido de fibra de vidro e resina poliéster, com 54% de teor de vidro em massa e espessura de 1,2 mm. Realizou-se o cálculo das propriedades mecânicas de cada compósito no programa MECH-Gcomp. As propriedades do núcleo foram retiradas, inicialmente, da literatura. Então, foi possível realizar a avaliação dos painéis pelo método dos elementos finitos utilizando elementos sólidos, comparando o comportamento dos dois tipos de painéis em relação aos carregamentos de compressão de núcleo, de compressão longitudinal e de flexão. Foram realizados ensaios nas faces isoladas e também nos painéis sanduíche completos. Para as faces, os ensaios foram de teor mássico de fibra de vidro, tração, compressão e cisalhamento Iosipescu, conforme as normas ASTM D5630, D3039/D3039M, D6641/D6641M e D7078/D7078M, respectivamente. Já para os painéis sanduíche, foram realizados os ensaios de compressão de núcleo, compressão longitudinal (edgewise) e cisalhamento do núcleo utilizando flexão, conforme as normas ASTM C365/C365M, C364/C364M e C393/C393M, respectivamente. Após os ensaios, foram calibrados os modelos do MEF, permitindo que os mesmos possam calcular outras configurações similares de painel sanduíche. Foi utilizado o programa Autodesk Simulation Composite Design para realizar a validação do ensaio de cisalhamento do núcleo. Concluiu-se que a análise de elementos finitos foi confiável em representar de forma realista o comportamento dos painéis sanduíche e a redução na espessura das faces do painel pode ser compensada com o aumento da sua resistência mecânica e rigidez por meio do aumento no teor mássico de reforço e trabalhando com a orientação do mesmo. / Sandwich panels are widely used in a variety of engineering applications and the study of their properties is fundamental for the expansion of their use. In this work, we studied sandwich panels with polyurethane core and fiberglass faces manufactured by the continuous lamination process. In the first configuration, the panel faces were made of fiberglass and polyester resin, with 39% glass content by mass and 1.9 mm thickness. In the second configuration, the panel faces were fabricated from fiberglass fabric and polyester resin, with 54% glass content by mass and 1.2 mm thickness. The mechanical properties of each composite were calculated in the MECH-Gcomp software. The properties of the core were initially taken from the literature. Then, it was possible to evaluate the panels by the finite element method using solid elements, comparing the behavior of the two types of panels in relation to the core compression loads, edgewise compression and bending. Tests were performed on the faces and also on the complete sandwich panels. For the faces, the tests were fiberglass mass content, tensile, compression and Iosipescu shear, according to ASTM D5630, D3039/D3039M, D6641/D6641M and D7078/D7078M, respectively. For sandwich panels, core compression, edgewise compression and core shear using bending tests were performed according to ASTM C365/C365M, C364/C364M and C393/C393M, respectively. After the tests, the FEM models were calibrated, allowing them to calculate other similar sandwich panel configurations. It was used Autodesk Simulation Composite Design software to validate the core shear test. It was concluded that the analysis of finite elements was reliable in realistically representing the behavior of the sandwich panels and the reduction in the thickness of the panel faces can be compensated with the increase of its mechanical resistance and stiffness by increasing the mass content of reinforcement and working with the orientation of the same.
6

Efeito do material da face nas propriedades mecânicas de painéis sanduíche para aplicação rodoviária

Garbin, Daniel Fernando January 2017 (has links)
Painéis sanduíche são largamente utilizadas em diversas aplicações de engenharia e o estudo de suas propriedades é fundamental para a ampliação de sua utilização. Neste trabalho, foram estudados painéis sanduíche com núcleo de poliuretano e faces de fibra de vidro fabricados pelo processo de laminação contínua. Na primeira configuração, as faces do painel foram fabricadas com manta de fibra de vidro e resina poliéster, com 39% de teor de vidro em massa e espessura de 1,9 mm. Na segunda configuração, as faces do painel foram fabricadas com tecido de fibra de vidro e resina poliéster, com 54% de teor de vidro em massa e espessura de 1,2 mm. Realizou-se o cálculo das propriedades mecânicas de cada compósito no programa MECH-Gcomp. As propriedades do núcleo foram retiradas, inicialmente, da literatura. Então, foi possível realizar a avaliação dos painéis pelo método dos elementos finitos utilizando elementos sólidos, comparando o comportamento dos dois tipos de painéis em relação aos carregamentos de compressão de núcleo, de compressão longitudinal e de flexão. Foram realizados ensaios nas faces isoladas e também nos painéis sanduíche completos. Para as faces, os ensaios foram de teor mássico de fibra de vidro, tração, compressão e cisalhamento Iosipescu, conforme as normas ASTM D5630, D3039/D3039M, D6641/D6641M e D7078/D7078M, respectivamente. Já para os painéis sanduíche, foram realizados os ensaios de compressão de núcleo, compressão longitudinal (edgewise) e cisalhamento do núcleo utilizando flexão, conforme as normas ASTM C365/C365M, C364/C364M e C393/C393M, respectivamente. Após os ensaios, foram calibrados os modelos do MEF, permitindo que os mesmos possam calcular outras configurações similares de painel sanduíche. Foi utilizado o programa Autodesk Simulation Composite Design para realizar a validação do ensaio de cisalhamento do núcleo. Concluiu-se que a análise de elementos finitos foi confiável em representar de forma realista o comportamento dos painéis sanduíche e a redução na espessura das faces do painel pode ser compensada com o aumento da sua resistência mecânica e rigidez por meio do aumento no teor mássico de reforço e trabalhando com a orientação do mesmo. / Sandwich panels are widely used in a variety of engineering applications and the study of their properties is fundamental for the expansion of their use. In this work, we studied sandwich panels with polyurethane core and fiberglass faces manufactured by the continuous lamination process. In the first configuration, the panel faces were made of fiberglass and polyester resin, with 39% glass content by mass and 1.9 mm thickness. In the second configuration, the panel faces were fabricated from fiberglass fabric and polyester resin, with 54% glass content by mass and 1.2 mm thickness. The mechanical properties of each composite were calculated in the MECH-Gcomp software. The properties of the core were initially taken from the literature. Then, it was possible to evaluate the panels by the finite element method using solid elements, comparing the behavior of the two types of panels in relation to the core compression loads, edgewise compression and bending. Tests were performed on the faces and also on the complete sandwich panels. For the faces, the tests were fiberglass mass content, tensile, compression and Iosipescu shear, according to ASTM D5630, D3039/D3039M, D6641/D6641M and D7078/D7078M, respectively. For sandwich panels, core compression, edgewise compression and core shear using bending tests were performed according to ASTM C365/C365M, C364/C364M and C393/C393M, respectively. After the tests, the FEM models were calibrated, allowing them to calculate other similar sandwich panel configurations. It was used Autodesk Simulation Composite Design software to validate the core shear test. It was concluded that the analysis of finite elements was reliable in realistically representing the behavior of the sandwich panels and the reduction in the thickness of the panel faces can be compensated with the increase of its mechanical resistance and stiffness by increasing the mass content of reinforcement and working with the orientation of the same.
7

Développement de vernis d'isolation électrique présentant des propriétés thermomécaniques améliorées à 180°C / Development of electrical insulating varnishes with improved thermomechanical properties

Heib, Bertrand 11 January 2011 (has links)
Cette thèse porte sur le développement de résines polyesterimides insaturés pour des applications de type vernis d'imprégnation pour isolation électrique. Il s’agit de matériaux polymères thermodurcissables, qui assurent la double fonction d'isolant et d'agent de cohésion du système isolé. Ils se différencient en classes thermiques, qui définissent leur température maximale d'utilisation. Dans le cadre de cette étude, nous cherchons à développer des produits de classe thermique supérieure ou égale à 180°C. Une première partie de cette étude a porté sur l'amélioration de deux produits commerciaux à base de polyesters insaturés à fonctions terminales imides. Notre attention s'est portée sur la modification de leur structure chimique, afin de voir comment les différents précurseurs utilisés influencent les propriétés des résines. Une seconde partie a consisté à développer de nouvelles résines à base de polyesterimides insaturés, à partir de trois types de précurseurs imides difonctionnels. / This thesis focuses on the development of unsaturated polyesterimide resins as impregnating varnishes for electrical insulation applications. These thermosetting polymer materials provide the dual function of insulating and cohesion agent of the isolated system. They differ in thermal classes, which define their maximum operating temperature. In this study, we tried to develop products with a thermal class above or equal to 180°C. The first part of this study focused on the improvement of two commercial products based on imide-endcapped unsaturated polyester. Our attention turned to the modification of their chemical structure, to see how the different precursors used affect the thermal and mechanical properties of resins. A second part was to develop new unsaturated polyesterimide resins, using three types of difunctional imide precursors.
8

A influência de cargas particuladas nas propriedades mecânicas de compósitos com resina poliéster insaturadas / Effect of fillers on mechanical properties of polymeric composites

Dalibor, Ingo Hermann 28 February 2013 (has links)
Made available in DSpace on 2016-12-08T17:19:20Z (GMT). No. of bitstreams: 1 Ingo H Dalibor.pdf: 1064360 bytes, checksum: e76ccd8c14da5a15a2f117ade49f4b1f (MD5) Previous issue date: 2013-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Particulate fillers have a broad application in the composites industry, mainly for cost reduction. But fillers may have also an influence on mechanical properties like strength, stiffness and strain. The scope of this dissertation is the mechanical characterization of particulate composites changing concentration from 1% to 20% in volume with an PVC rod as reinforcement. Initially pull out tests were applied to determine critical length of reinforcement. Critical length measures load transfer on interface between matrix and reinforcement, which is main factor to improve composite s strength. Critical length as a function of filler concentration showed a remarkable similarity for all fillers studied. At about 5% volume fraction all curves showed a minimum, it means, the shear strength is a maximum in this point. Finally, mechanical properties in flexural tests without PVC reinforcement were determined showing at low filler concentration significant variation. Statistical significance tests showed mechanical properties aren t a linear function to concentration. Flexural tests on particulate composite with PVC reinforcement showed strength reduction, but on elastic modulus and strain, different effects were realized, depending on filler used. It means, a 3 phase composite may have a synergy or dissociative effect when filler and reinforcement were applied together. / A carga particulada, normalmente utilizada para redução de custos, pode ter influência nas propriedades mecânicas dos compósitos com matriz de poliéster insaturado. Foram confeccionados corpos de prova com concentração volumétrica variando entre 1 e 20% na matriz de poliéster. Inicialmente foi analisada a força de adesão na interface do reforço e a matriz. Com a força de adesão é transferida a tensão da matriz para o reforço, ocorrendo um aumento da resistência do compósito. A força de adesão pode ser determinada pelo comprimento crítico do reforço, neste caso uma haste de PVC, através de um ensaio de arrancamento, conhecido também como pull out . A curva do comprimento crítico em função da concentração de carga mostrou uma notável semelhança com todas as cargas testadas, havendo um mínimo em torno da concentração volumétrica nominal de 5%. Posteriormente, através de ensaios de flexão, foram determinadas as propriedades mecânicas do compósito, que são o módulo de elasticidade, resistência e a deformação máxima nas concentrações acima mencionadas. Os ensaios foram realizados sem e com a haste de PVC. Os efeitos das cargas foram muito distintos em cada caso. O melhor resultado foi obtido no módulo de elasticidade do compósito com a matriz poliéster com carga de vidro moído na concentração de 5% em volume e uma haste de PVC. Nos outros casos as cargas testadas tiveram efeito negativo nas propriedades. A haste de PVC trouxe um efeito positivo apenas na deformação máxima sem a utilização de carga na matriz. Em todos os outros casos o efeito da haste de PVC foi negativo.
9

Comp?sito refor?ado com sisal para aplica??o na moda

Oliveira, Jos? Orlando de 30 March 2012 (has links)
Made available in DSpace on 2014-12-17T14:58:14Z (GMT). No. of bitstreams: 1 JoseOO_DISSERT.pdf: 1240113 bytes, checksum: dbf41a478040a880c57e2dbf04e10cda (MD5) Previous issue date: 2012-03-30 / The objective of this research is the fabrication of a composite reinforced with dyed sisal fiber and polyester matrix for application in the fields such as, fashion, clothing, interior textiles; fashion accessories are some of the examples. For the fabrication of the composite, the sisal fibers were subjected to processes such as: chemical treatment with sodium hydroxide (NaOH) in the removal of impurities; bleaching for removing the yellowish color of the natural fiber and dyeing with direct dyes to confer the colors blue, green and orange. The search for new technologies ecologically correct has become a major concern in recent decades. Studies show that composite polymer reinforced by natural fibers is suitable for a large number of applications, and its use is advantageous in terms of economic and ecological. The dyed fibers were cut to a length of 30 mm, is used in the confection of webs. For this purpose, a web preparer by immersion, developed in the Laboratory of Chemical Textile of UFRN. The composite sheets measuring 300 x 300 x3 mm were molded by compression, with unsaturated orthophthalic polyester as matrix, and the samples in sizes 150 x 25 x 3 mm were cut with the aid of a laser machine, to be subjected to traction and flexion. The mechanical properties of traction and flexion in three points were performed in the Laboratory of metal and mechanical tests of Materials Engineering of UFRN. The resulting samples from the tests were evaluated in scanning electron microscope (SEM) at CTGas RN. On the basis of the analysis of the results from the mechanical tests, it was observed that the composite had good mechanical behavior, both in traction as in flexion. Furthermore, it was observed that in the water absorption test, the samples had a different percentage among themselves, this occurred due to the variation of density found in the fibre webs. The images of the SEM showed the failures from the manufacturing process and the adhesion of fibre/matrix. When the samples were prepared with the dyed fibers to be applied in fashion, the results were positive, and it can be concluded that the main objective of this work was achieved / A busca por novas tecnologias ecologicamente corretas tem se tornado uma grande preocupa??o nas ?ltimas d?cadas. Estudos comprovam que comp?sitos polim?ricos refor?ados por fibras naturais s?o adequadas a um grande n?mero de aplica??es e seu uso ? vantajoso em termos econ?micos e ecol?gicos. O objetivo desta pesquisa ? a fabrica??o de um comp?sito refor?ado com fibra de sisal tingida e matriz de poli?ster para aplica??o na moda: vestu?rio, t?xteis lar, acess?rios de moda etc. Para o seu beneficiamento, as fibras de sisal foram submetidas aos diversos processos: tratamento qu?mico com hidr?xido de s?dio (NaOH) na retirada das impurezas; alvejamento para remo??o da cor amarelada natural da fibra e tingimento com corantes diretos para conferir as cores azul, verde e alaranjado. As fibras tingidas foram cortadas com comprimento de 30 mm e utilizadas na confec??o das mantas. Para isso utilizou-se um preparador de manta por imers?o, desenvolvido no Laborat?rio de Qu?mico T?xtil da UFRN. Os comp?sitos medindo 300 x 300 x 3 mm foram moldados por compress?o, com poli?ster insaturado ortoft?lico como matriz, e as amostras nos tamanhos 150 x25 x3 mm foram cortadas com aux?lio de uma m?quina ? laser, para serem submetidas ? an?lise mec?nica de tra??o e flex?o. As propriedades mec?nicas de tra??o e flex?o em tr?s pontos foram realizadas no Laborat?rio de Metais e Ensaios Mec?nicos de Engenharia de Materiais da UFRN. As amostras resultantes das propriedades mec?nicas foram avaliadas no Microscopio Eletronico de Varredura (MEV) no CTG?s RN. Com base nas an?lises dos resultados dos ensaios mec?nicos, observou-se que os compositos tiveram bom comportamento mec?nico, tanto na tra??o como na flex?o. Tamb?m observou-se que no ensaio de absor??o de ?gua, as amostras tiveram um percentual diferente entre si, isso ocorreu devido ? varia??o da densidade encontrada nas mantas. As imagens do MEV mostraram as falhas provenientes do processo de fabrica??o e a ades?o fibra/matriz. Quando foram preparadas as amostras com as fibras tingidas para serem aplicadas na moda, os resultados foram positivos e pode-se concluir que o objetivo principal do presente trabalho foi atingido
10

Efeito do material da face nas propriedades mecânicas de painéis sanduíche para aplicação rodoviária

Garbin, Daniel Fernando January 2017 (has links)
Painéis sanduíche são largamente utilizadas em diversas aplicações de engenharia e o estudo de suas propriedades é fundamental para a ampliação de sua utilização. Neste trabalho, foram estudados painéis sanduíche com núcleo de poliuretano e faces de fibra de vidro fabricados pelo processo de laminação contínua. Na primeira configuração, as faces do painel foram fabricadas com manta de fibra de vidro e resina poliéster, com 39% de teor de vidro em massa e espessura de 1,9 mm. Na segunda configuração, as faces do painel foram fabricadas com tecido de fibra de vidro e resina poliéster, com 54% de teor de vidro em massa e espessura de 1,2 mm. Realizou-se o cálculo das propriedades mecânicas de cada compósito no programa MECH-Gcomp. As propriedades do núcleo foram retiradas, inicialmente, da literatura. Então, foi possível realizar a avaliação dos painéis pelo método dos elementos finitos utilizando elementos sólidos, comparando o comportamento dos dois tipos de painéis em relação aos carregamentos de compressão de núcleo, de compressão longitudinal e de flexão. Foram realizados ensaios nas faces isoladas e também nos painéis sanduíche completos. Para as faces, os ensaios foram de teor mássico de fibra de vidro, tração, compressão e cisalhamento Iosipescu, conforme as normas ASTM D5630, D3039/D3039M, D6641/D6641M e D7078/D7078M, respectivamente. Já para os painéis sanduíche, foram realizados os ensaios de compressão de núcleo, compressão longitudinal (edgewise) e cisalhamento do núcleo utilizando flexão, conforme as normas ASTM C365/C365M, C364/C364M e C393/C393M, respectivamente. Após os ensaios, foram calibrados os modelos do MEF, permitindo que os mesmos possam calcular outras configurações similares de painel sanduíche. Foi utilizado o programa Autodesk Simulation Composite Design para realizar a validação do ensaio de cisalhamento do núcleo. Concluiu-se que a análise de elementos finitos foi confiável em representar de forma realista o comportamento dos painéis sanduíche e a redução na espessura das faces do painel pode ser compensada com o aumento da sua resistência mecânica e rigidez por meio do aumento no teor mássico de reforço e trabalhando com a orientação do mesmo. / Sandwich panels are widely used in a variety of engineering applications and the study of their properties is fundamental for the expansion of their use. In this work, we studied sandwich panels with polyurethane core and fiberglass faces manufactured by the continuous lamination process. In the first configuration, the panel faces were made of fiberglass and polyester resin, with 39% glass content by mass and 1.9 mm thickness. In the second configuration, the panel faces were fabricated from fiberglass fabric and polyester resin, with 54% glass content by mass and 1.2 mm thickness. The mechanical properties of each composite were calculated in the MECH-Gcomp software. The properties of the core were initially taken from the literature. Then, it was possible to evaluate the panels by the finite element method using solid elements, comparing the behavior of the two types of panels in relation to the core compression loads, edgewise compression and bending. Tests were performed on the faces and also on the complete sandwich panels. For the faces, the tests were fiberglass mass content, tensile, compression and Iosipescu shear, according to ASTM D5630, D3039/D3039M, D6641/D6641M and D7078/D7078M, respectively. For sandwich panels, core compression, edgewise compression and core shear using bending tests were performed according to ASTM C365/C365M, C364/C364M and C393/C393M, respectively. After the tests, the FEM models were calibrated, allowing them to calculate other similar sandwich panel configurations. It was used Autodesk Simulation Composite Design software to validate the core shear test. It was concluded that the analysis of finite elements was reliable in realistically representing the behavior of the sandwich panels and the reduction in the thickness of the panel faces can be compensated with the increase of its mechanical resistance and stiffness by increasing the mass content of reinforcement and working with the orientation of the same.

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