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Análise numérica de uma ligação mista viga-pilar com chapa passante
(Universidade Federal de São Carlos, 2014-04-14) Santos, Tiago José dos; Nardin, Silvana de; https://lattes.cnpq.br/5587716781980132; https://lattes.cnpq.br/2301103903408062
Among all of the existing structural systems, the steel-concrete composite elements outstands because it takes advantage of the properties of both materials in the same element. Unlike the system in reinforced concrete cast in situ, the steel-concrete composite system is not monolithic, and therefore the global behavior of the structure is mainly linked to the behavior of the connections. Currently, the beam-column connections have been the subject of theoretical and experimental studies to better understand their structural behavior. This concern has become even bigger with the introduction of requirements on steel-concrete composite connections in the Brazilian standard ABNT NBR 8800:2008. In order to contribute to this subject, in this work is studied by numerical modeling, a detail of a composite beam-column connection with shear plate using numerical models. The numerical analysis performed in the computer package ANSYS® was divided in two phases: validation of the numerical model from experimental results and subsequent parametric analysis. Despite of the simplifications adopted in the numerical simulation, the results were satisfactory and representative of the experimental behavior, especially for Force vs. Displacement at the end of the beam. Once validated the numerical model, a parametric study was conducted in order to evaluate the influence of some parameters on the bearing capacity of connections, such as the concrete slab reinforcement ratio, the slab thickness and the steel beam depth. The results of the parametric analysis showed that the variation of the slab thickness was the parameter with more influence on the bearing capacity of the composite connection with shear plate.
Estudo da cinética de oxidação em altas temperaturas da liga SV15 aplicada na fabricação de sedes de válvulas de escape de motores automotivos
(Universidade Federal de São Carlos, 2014-04-14) Alano, José Henrique; Kuri, Sebastião Elias; https://lattes.cnpq.br/6842072916153866; https://lattes.cnpq.br/0138403357197508
The SV15 alloy is applied in the production of the exhaust valve seats of automotive engines. The conditions of service in which the part is submitted require materials resistant to oxidation because of high temperature and aggressive atmosphere in which the material is exposed. The evaluation of high-temperature oxidation of the SV15 alloy is important therefore contributing in the selection or not of the material in other applications as severe as the automotive engine. The high-temperature oxidation in the alloy SV15 was studied by thermogravimetry in an atmosphere of O2 for a period of one hour at temperatures of 660°C, 740°C, 860°C and 900°C. The microstructure and chemical composition of the alloy were determined by scanning electron microscopy (SEM), and the phases present in the alloy were studied by X-ray diffraction (XRD). The SEM technique was also used to assess the microstructure, morphology, thickness and chemical composition of the oxide layer. To determine the phases presented by the oxide layer were used the techniques of Fourier transform infrared spectroscopy (FTIR), FT-Raman and XRD. The oxides formed at 660°C and 740°C follow the linear rate law, while the layers formed at 860°C and 900°C showed two stages of oxidation, an initial linear stage and a second parabolic stage. The first stage of oxidation showed an oxide formed mainly by NiCr2O4 while the second stage was composed of Cr2O3. The oxidation mechanism in the first stage of oxidation was controlled by the reaction rate of the oxygen with the metallic substrate, while the second stage of oxidation was controlled by reducing the diffusion of Ni+2 through the NiCr2O4 layer.