Electromagnetic Stirring Versus Ecap: Morphological Comparison Of Al-si-cu Alloys To Make The Microstructural Refinement For Use In Ssm Processing

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)This work evaluates themorphological evolution at the semisolid state of the Al-4.0wt% Si-2.5wt% Cu alloy produced by direct chill casting under electromagnetic stirring (EMS) and by one equal channel angular pressing (ECAP) pass. The ECAP emerged as a promising technique capable of reduction and homogeneous metals microstructure imposing large deformations occurs in amatrix that contains two channels of the same cross-sectional area and forms an angle of 120 degrees. The materials were submitted to reheating treatment in condition of 60% solid fraction at treatment times of 0, 30, and 90 s. Comparing the two cases, we have the presented ECAP process that had an excellent response to the recovery and recrystallization mechanisms, and refined microstructures ideal for thixoforming were produced. Primary particle sizes of about 15 mu m and grain sizes of about 75 mu m and a circularity shape factor of more than 0.60 were obtained. The low silicon alloy, Al-4.0wt% Si-2.5wt% Cu, presented excellent refinement when processed via equal channel angular pressing, presenting good morphological stability at the semisolid state, without significant changes in size or shape of the solid particles. This fully globular structure is favourable for thixoforming processes.Sao Paulo Research Foundation (FAPESP) [2009/08478-1, 2013/09961-3, 2015/22143-3]National Council for Scientific and Technological Development (CNPq) [306896/2013-3]Coordination for the Improvement of Higher Education Personnel (CAPES)Faculty of Mechanical Engineering at the University of Campinas (UNICAMP)Federal Institute of Education, Science and Technology of Sao Paulo campus Braganca Paulista (IFSP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Electromagnetic stirring versus ECAP: morphological comparison of al-si-cu alloys to make the microstructural refinement for use in SSM processing

This work evaluates the morphological evolution at the semisolid state of the Al-4.0wt%Si-2.5wt%Cu alloy produced by direct chill casting under electromagnetic stirring (EMS) and by one equal channel angular pressing (ECAP) pass. The ECAP emerged as a promising technique capable of reduction and homogeneous metals microstructure imposing large deformations occurs in a matrix that contains two channels of the same cross-sectional area and forms an angle of 120°. The materials were submitted to reheating treatment in condition of 60% solid fraction at treatment times of 0, 30, and 90 s. Comparing the two cases, we have the presented ECAP process that had an excellent response to the recovery and recrystallization mechanisms, and refined microstructures ideal for thixoforming were produced. Primary particle sizes of about 45 μm and grain sizes of about 75 μm and a circularity shape factor of more than 0.60 were obtained. The low silicon alloy, Al-4.0wt%Si-2.5wt%Cu, presented excellent refinement when processed via equal channel angular pressing, presenting good morphological stability at the semisolid state, without significant changes in size or shape of the solid particles. This fully globular structure is favourable for thixoforming processes201617CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP306896/2013-3Não tem2009/08478-1; 2013/09961-3; 2015/22143-

Microstructural characterization of the A356 alloy in different processing routes used in the thixoforming process

This work aims to evaluate different routes of raw material production to be used in thixoforming process. The semisolid materials exhibit particular structural characteristics, such the characteristic non dendritic structure. The studies for the production of near-net-shape parts have progressed together with the studies of material weight reduction on the automobile industries production lines. In general the advantages are energy saving, manufacturing steps reduction, productivity and quality increasing. Five processing routes have been investigated (conventional casting, electromagnetic stirring, grain refinement technique and different cooling rates) through microstructural characterizations, conventional metallographic and colour metallography. The material used in this study was the A356 alloy (commercial) having a hypoeutectic structure and grain size of about 750 mm and primary dendrite arm spacing size of around 80 mm, the combination of electromagnetic stirring + grain refining + high cooling rate provided the best route processing to obtain a refined structure, with grain sizes of around 240 mm, being feasible at the thixoforming process. Note also that using conventional metallography (black and white) all routes tested showed almost the same primary dendrite arm spacing size values ie had identical characteristics. Importantly, only with the characterization via polarized colour metallography is that was achieved in fact the best processing route definition.Keywords: A356 alloy, casting, electromagnetic stirring, grain refinement, thixoforming

Influence Of The Radial Clearance Of A Squeeze Film Damper On The Vibratory Behavior Of A Single Spool Gas Turbine Designed For Unmanned Aerial Vehicle Applications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)This study presents a numerical investigation using the finite element method on the vibratory behavior of a single spool gas turbine designed for unmanned aerial vehicle applications. The shaft of the rotor-bearing system is supported on a front bearing composed of a deep groove ball bearing with a vibration absorber element and a rear squeeze film damper bearing. Three radial clearances for the squeeze film damper were analyzed to determine the best geometric configuration for the rear bearing, considering the rotordynamic performance of the entire system. Whirl speeds and unbalanced system responses were carefully evaluated to determine the best radial clearance for the squeeze film damper. After defining the best radial clearance, a transient analysis was performed to simulate the transition of the system through resonance, and a spectral map is presented to illustrate the vibratory behavior of the system considering the influence of all related important frequencies. The rotordynamic behavior of the system is predicted, and vibration problems are avoided. Its mechanical drawings were released to manufacturing, and the first prototype is in the experimental test phase, thus indicating that the numerical results presented in this study are consistent.Instituto Tecnologico de AeronauticaTGM Turbinas LtdaCAPES and CNPq [385582/2006-4]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Derivação de sistemas multiagentes industriais através do framework O-MaSE

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2013.O problema de derivação de sistemas multiagentes industriais envolve complexos aspectos. Uma derivação consiste basicamente em gerar uma instância de sistema multiagente a partir de um modelo ou arquitetura genérica, com posteriores adaptações para um certo caso particular. No caso específico, este caso particular corresponde a um dado chão-de-fábrica, a ser gerenciado pelo sistema multiagente derivado. A complexidade deste problema reside principalmente na natureza do cenário de chão-de-fábrica, que agrega inúmeros aspectos que devem ser consideradas no momento da modelagem do sistema. A presença de uma estrutura heterogênea de sistemas legados e equipamentos deve ser muito bem analisada e descrita para que o resultado final seja coerente com as características, layout e funcionamento do chão de fábrica em questão. A abordagem de solução utilizada neste trabalho para fazer frente a essa complexidade foi a de executar uma derivação com o apoio de uma metodologia especialmente desenvolvida para tal. Esta metodologia é composta por etapas criadas a partir da análise e escolha dos meta-modelos do framework O-MaSE, que comporão a metodologia propriamente dita. Além disto, para suportar os necessários requisitos, duas etapas específicas de descrição de cenários industriais foram criadas em relação ao modelo original do O-MaSE. Uma para especificar o chão de fábrica e outra para representação do conhecimento deste, o que é feito através de uma ontologia. O resultado obtido pela derivação elaborada e pela adaptação feita da O-MASE é representado pela geração de códigos-base de agentes que representam virtualmente o cenário. Com a utilização do framework O-MaSE foi possível conceber e formalizar esta metodologia via diagramas UML e outras documentações auxiliares referentes à especificação dos equipamentos.2014-08-06T17:11:39