No abstract

This study compared the variation of the dynamic elastic modulus (E) of three types of composite pipes made by the filament winding process and a steel alloy specimen, according to signal source changes. The specimens were produced with three different winding angles, i.e., ±50°, ±52.5°, and ±55°. The moduli were obtained through a known signal source and the angular variation, according to two sensors positioned over the specimen's surface. In a previous article, the variation in the velocity of acoustic emission (AE) signals, performed in the same type of pipes, was discussed based on the standards for glass fiber-reinforced epoxy (GFRE) filament wound specimens. This work took these preliminary findings to compare with the results found for steel alloy pipes (SAE 1020). This data was used with appropriate equations to determine the dynamic elastic moduli of each material. It was found that, even for small angular differences, the modulus changes position concerning the lamination angle. Thus, the lower the quality control, the lower the final product with composite materials. As expected, for isotropic materials such as steel alloys, the modulus remains constant along the angles, while for anisotropic ones, it is dependent on the principal directions of stress and strain, or on the other hand, dependent on the correlation between the angular wave velocity of the AE signals.

No mundo todo é antigo o interesse por substituir a madeira nativa por madeira de reflorestamento de crescimento rápido, visando maiores quantidades de material em menor tempo sem perdas em suas propriedades resistivas. Esta pesquisa consiste na comparação do comportamento de peças estruturais in natura com peças estruturais tratadas com resina poliuretana, à base de mamona, em relação à resistência à tração e a flexão, igualmente serão feitos testes para verificar a taxa de absorção e inchamento da madeira após o tratamento com a resina. O tratamento dado as peças estruturais visam melhorar o comportamento mecânico das mesmas. A resina poliuretana bicomponente à base óleo de mamona, fabricada pela empresa Imperveg, foi utilizada no tratamento das peças. Foram realizadas avaliações segundo a NBR7190 (1997) visando caracterizar as propriedades físicas e mecânicas das peças de madeira e os resultados obtidos foram submetidos à análise estatística pelos métodos Anova e Regressão Linear. Palavras-chave: Resina poliuretana à base de Óleo de Mamona, madeira engenheirada, tração.

The impacts caused by RCCs are growing exponentially each year, which is why it is necessary to create measures to mitigate and minimize such an effect. The purpose of this research was to evaluate the physicalmechanical properties of the concrete from the gradual replacement of the natural fine aggregate by the recycled aggregate. The recycled concrete was made with substitutions of 20, 40, 60, 80 and 100% of recycled aggregate, whose water / cement factor was 0.7. Test specimens were produced and after the cure time of 7, 14 and 28 days the specimens were ruptured. It was possible to analyze that with the increase of the recycled aggregate substitution, the concrete strength increased, but did not reach an average resistance of 20 Mpa. Therefore it is possible to conclude that the use of recycled aggregate in the manufacture of low resistance concrete is.

This study relies on comparing the behavior of structural timber pieces in naturawith pieces treated with castor oil-based polyurethane resin, with regard to the resistance to axial compression. The treatment attempts to improve the mechanical behavior of the wood and, to this end, two species will be compared: Pinus and Eucalyptus. Evaluations will be carried out according to NBR7190(1997)aiming to characterize physical and mechanical properties of the pieces and the results will be submitted to the statistical analysis by the Anova and Linear Regression methods