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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

An?lise de crit?rios de falhas em l?minas refor?adas com tecidos unidirecionais de fibra de curau?

Ferreira, Lucemaide Batista Miranda 06 August 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T23:20:44Z No. of bitstreams: 1 LucemaideBatistaMirandaFerreira_TESE.pdf: 4494748 bytes, checksum: f35753b1191ecb306cd0973efb042a35 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T23:33:29Z (GMT) No. of bitstreams: 1 LucemaideBatistaMirandaFerreira_TESE.pdf: 4494748 bytes, checksum: f35753b1191ecb306cd0973efb042a35 (MD5) / Made available in DSpace on 2016-06-01T23:33:29Z (GMT). No. of bitstreams: 1 LucemaideBatistaMirandaFerreira_TESE.pdf: 4494748 bytes, checksum: f35753b1191ecb306cd0973efb042a35 (MD5) Previous issue date: 2015-08-06 / O presente trabalho tem como objetivo fazer uma an?lise das propriedades mec?nicas e do comportamento mec?nico de duas l?minas refor?adas com tecido unidirecional de fibra de curau? com diferentes fra??es volum?tricas, baseado em crit?rios de falha definidos em literatura. Os comp?sitos, que apresentam matriz polim?rica e refor?o com tecido unidirecional de fibra de curau?, foram submetidos a ensaios de tra??o e cisalhamento em uma s?rie de corpos de provas normatizados cuja orienta??o das fibras direcionadas em ?ngulos de 0?, 10?, 20?, 75? e 90? para a l?mina com fra??o volum?trica de 30% e 0?, 30?, 45?, 60?, e 90? para a l?mina com fra??o volum?trica de 22%, para ensaios de tra??o e para ensaio de cisalhamento a orienta??o do ?ngulo do refor?o foi de 90?. Os ensaios foram executados em uma m?quina universal de tra??o e coletados os dados das propriedades mec?nicas dos corpos de prova dos comp?sitos. Estes dados experimentais foram inseridos nas equa??es te?ricas que definem os crit?rios de falha, como tamb?m, tratados graficamente para an?lise dos resultados e compara??o entre os ?ngulos de orienta??o do refor?o. Constatou-se uma grande dispers?o entre os dados experimentais do m?dulo de Elasticidade e do Coeficiente de Poisson em rela??o ao comportamento te?rico principalmente para a l?mina com menor fra??o volum?trica. O comp?sito com orienta??o de refor?o a 0? apresentou a maior resist?ncia ? tra??o em rela??o ?s demais inclina??es para as duas l?minas. No entanto, em rela??o aos crit?rios de falha as l?minas tiveram comportamentos diferentes. Para a l?mina com fra??o volum?trica 30%, os quatro crit?rios estudados nesta Tese apresentaram boa concord?ncia em termos de resist?ncia, mas para a l?mina com fra??o volum?trica de 22%, apenas o crit?rio de Tsai-Will e Hashin apresentaram boa concord?ncia. . / This study aims to analyze the mechanical properties and the mechanical behavior of two laminas reinforced with unidirectional fabric curau? with different fiber volume fractions, based on failure criteria defined in the literature. The composites which have polymeric matrix and reinforcement with unidirectional fabric curaua fiber, were submitted to tensile and shear tests at a series of specimens standardized whose fiber orientation directed at angles of 0?, 10?, 20?, 75? and 90? to the lamina with volume fraction of 30% and 0?, 30 ?, 45 ?, 60 ?, and 90 ? to the lamina with volume fraction of 22% to tensile tests and shear tests the direction of strengthening the angle was 90 ? to the x axis (direction of the applied load). The tests were performed in a universal machine traction and collected the data of mechanical properties of the composite specimens. These experimental data were entered in the theoretical equations that define the failure criteria, as well as graphically treated to analyze the results and compare the enhanced orientation angles. It found major disparities between the experimental data of elastic modulus and Poisson's ratio in relation to the theoretical behavior primarily to the lamina with a lower volume fraction. The composite reinforcement orientation at 0 ? showed the highest tensile strength compared to other inclinations for the two laminas. However, regarding the failure criteria laminas have different behaviors. To the lamina with volume fraction 30%, the four criteria studied in this thesis showed equivalent results in terms of resistance and to the blade with volume fraction of 22%, only the maximum stress criterion was not satisfactory in representing experiemtais data.

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