128 resultados para compression ratio


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This paper presents a new technique to model interfaces by means of degenerated solid finite elements, i.e., elements with a very high aspect ratio, with the smallest dimension corresponding to the thickness of the interfaces. It is shown that, as the aspect ratio increases, the element strains also increase, approaching the kinematics of the strong discontinuity. A tensile damage constitutive relation between strains and stresses is proposed to describe the nonlinear behavior of the interfaces associated with crack opening. To represent crack propagation, couples of triangular interface elements are introduced in between all regular (bulk) elements of the original mesh. With this technique the analyses can be performed integrally in the context of the continuum mechanics and complex crack patterns involving multiple cracks can be simulated without the need of tracking algorithms. Numerical tests are performed to show the applicability of the proposed technique, studding also aspects related to mesh objectivity.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The connections in the wood structures are the places with high concentrations of stresses and therefore are more fragile than the rest of the structure. The connections between pieces of wood can be made by metal pins (nails or screws). The compression and embedment strength has significant influence on the calculation of the connections. The main aim of this work was to evaluate the compression and embedment strength in the directions parallel, inclined at 45° and normal to the grain, using standard specimens according to ABNT NBR 7190/1997 standard. The compression and embedment strength were initially evaluated according to ABNT NBR 7190/1997, which admits the deformation of 2‰ as limit of embedment and the ratio between the ultimate strength and the area of application of load in the specimen for the compressive strength. Afterward, the embedment strength was evaluated by the EUROCEDE 5 /1995 European standard, which use the limit of 5 mm of the displacement for the embedment. Specimens of Pinus oocarpa, Cumaru and Pinus taeda were used in tests to calibration of equipment and specimens of Pinus taeda and Eucalipto citriodora were used to compare the results of strength. The results of strength were evaluated based on statistical analysis. The results of compressive strength for the Pinus taeda showed no significant differences in embedment strength in the directions parallel and normal to the grain. For the Eucalipto citriodora only in the direction parallel to grain the compression strength was not significant compared with the embedment strength. For both species, only the parallel compression strength and inclined at 45o to the grain, which were to the grain, which were admitted the strain of 2‰ were not significantly different compared with the compression strength determined according to ABNT NBR 7190/1997. The normal compression strength obtained according to ABNT NBR 7190/1997 and ultimate compression strength not ...

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The search for a more aware use of available raw materials has led to a need to create more sustainable products. The use of natural fibers to reinforce cement, for instance, has been widely studied in the past decades because of the possibility that they can improve material properties such as thermal resistance and to compression, besides conferring a decrease in their total weight. This present study aimed at to conduct preliminary studies on the thermal resistance of the composite cement - Cellulose Pulp, using waste from the pulp and paper industry. Through experiments, it was found that the composite manufactured using the ratio 30 % Portland cement and 70 % pulp, showed satisfactory results regarding its thermal resistance, so it could be considered as a potential thermal insulation material, for use in constructions