171 resultados para modulus of rupture


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The glued-laminated lumber (glulam) technique is an efficient process for making rational use of wood. Fiber-Reinforced Polymers (FRPs) associated with glulam beams provide significant gains in terms of strength and stiffness, and also alter the mode of rupture of these structural elements. In this context, this paper presents a theoretical model for designing reinforced glulam beams. The model allows for the calculation of the bending moment, the hypothetical distribution of linear strains along the height of the beam, and considers the wood has a linear elastic fragile behavior in tension parallel to the fibers and bilinear in compression parallel to the fibers, initially elastic and subsequently inelastic, with a negative decline in the stress-strain diagram. The stiffness was calculated by the transformed section method. Twelve non-reinforced and fiberglass reinforced glulam beams were evaluated experimentally to validate the proposed theoretical model. The results obtained indicate good congruence between the experimental and theoretical values.

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Aramid fiber reinforced polymer composites have been used in a wide variety of applications, such as aerospace, marine, sporting equipment and in the defense sector, due to their outstanding properties at low density. The most widely adopted procedure to investigate the repair of composites has been by repairing damages simulated in composite specimens. This work presents the structural repair influence on tensile and fatigue properties of a typical aramid fiber/epoxy composite used in the aerospace industry. According to this work, the aramid/epoxy composites with and without repair present tensile strength values of 618 and 680MPa, respectively, and tensile modulus of 26.5 and 30.1 GPa, respectively. Therefore, the fatigue results show that in loads higher than 170 MPa, both composites present a low life cycle (lower than 200,000 cycles) and the repaired aramid/epoxy composite presented low fatigue resistance in low and high cycle when compared with non-repaired composite. With these results, it is possible to observe a decrease of the measured mechanical properties of the repaired composites.

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After concluding the main phase of commercial exploration of latex (about 30 years ago), rubber wood plantations can be utilized as an alternative source of wood for sawmills and other wood based products with more aggregate value; tendency already confirmed in countries of southeastern Asia. The main purpose of this research was to evaluate the influence of dynamic modulus of elasticity veneers on the mechanical performance in the bending of plywood made from Hevea brasiliensis. For this study, rubber tree veneers were sorted in three classes of dynamic modulus of elasticity: low (from 4887-7323 MPa), medium (from 8200-8948 MPa) and high (from 10979-13010 MPa). Panels were produced according to five treatments with different veneer classes and arrangements. Results showed significant effect of the treatments in the mechanical performance in the bending of panels. Panels with better mechanical performance were produced exclusively with medium and high dynamic modulus of elasticity. Panels made with low modulus of elasticity veneers presented lower mechanical performance even when combined with high modulus of elasticity veneers.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Ciências Sociais - FFC

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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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)