Estudo da usinagem por torneamento de ligas de alumínio

The non-ferrous materials have got so many mechanical, physical and chemical advantageous properties so that is provided to them consolidated position in industry. In this context, aluminium alloys have been seen a lot on many applications of engineering areas – specially on automotive, aeronautical and aerospace due to their main properties such as low density, high corrosion resistance, favorable structure weight / material resistance relation, among others characteristics that are mencioned through this study. This study aims to analyze the aluminium alloys behavior on a general context when they are used on turning process, taking for examples the 6262 and 7050 aluminium alloys. In this way, the analysis studies the datas obtained during the turning tests realized on 3 steps each one; those datas are concerning the medium and total rugosities – obtained with the assistance of a portable Surface Roughness Finish Tester, as well as the chips obtained during the tests - visual analysis, and the cutting tools wear – with the assistance of an optical microscope, under different conditions of application of cutting fluids (dry machining, application of coolant in abundance and MQL – Minimum Quantity of Lubricant). The results concerning this study show detailed information about influence of cutting fluids on the machining by turning of the aluminium alloys related on this work and also about aluminium alloys in general when they are used on turning processes with different conditions from one another. By this way, it was evident the MQL technique is the best one for the 6262 alloy. However, for 7050 alloy, it was evident that the dry machining is responsible for the best results

Dimensionamento de trocadores de calor aplicados à refrigeração da água do molde de um processo de lingotamento contínuo

This study aims to determine the most suitable type of heat exchanger to be applied to the water cooling the mold of a continuous casting process. Basically been studied four types of heat exchangers: shell and tube operating in counterflow, shell and tube operating in parallel flow, plate type and operating counterflow and plates operating in parallel flow. Initially is displayed design of heat exchangers for the conditions of the proposed application. With the heat exchangers dimensioned comparisons were made in order to set the heat exchanger more suitable for application. In the study, one comes to the conclusion that the plate type heat exchangers operating shows counterflow major advantage for this application

Calor e temperatura: uma revisão dos conceitos nas diferentes abordagens físicas

This work research and analyses the formulations and concepts of heat and temperature presented in Physics textbooks. These issues are deemed important because students often have difficulties differentiating and understanding such concepts, which compromises their education. The goal is to show that well-established relationships between Physical quantities such as energy, pressure, heat and temperature, even in different theories of Classical and Quantum Physics are not enough to define either temperature or heat. It also presents simple experiments that complement the teaching and learning of these concepts

Análise preliminar para a estimativa da perda de calor sensível de um fluido homogêneo térmico em um reservatório de geometria cilindrica

This work analyzed the loss of sensible heat from one fluid to be considered homogeneous heat distribution on a thermal reservoir with cylindrical geometries composite insulating layers. We studied two thermal reservoirs with a volume of 20 liters, and the first has a layer thickness of 75 mm of expanding polyurethane foam wrapped in the polycarbonate container and the second container has only layer thickness of 5 mm of polycarbonate, as insulation of fluid of the external environment. The experimental results are compared with theoretical results obtained through a calculation script, displayed and detailed during the work development, from the theory of energy balance. The maximum error introduced between the theoretical and experimental results were 3.5% and 1.4% respectively for the Boilers with or without a polyurethane coating

Processo de fabricação de tarugos pelo método HotTop de ligas de alumínio da série 6XXX e as não conformidades desse processamento

The goal of this work is to report some problems that occur in the in the production of aluminum billets (series 6XXX) produced by the hot top process in the Alcoa aluminum Inc. The aluminum fabrication process is described from its first stage, since the mining until the reduction, smelting and treatment of the metal. One of the plant’s final product, are billets for clients that produce profiles by extrusion. The product’s final quality highly depends on the whole production process. Therefore it’s necessary to use good practices in the treatment of the metal, follow up its fabrication and control its thermal treatment, in order to meet the required standards to satisfy the clients. The billet’s production method and its variables will be detailed through temperature and casting speed, cone of water flow, cooling rate, duration of thermal treatment, degassing and metal “in line “filtering, in other words when it’s still found in its liquid state. The non-conformities of the process were studied by metallographic analysis, both macrostutural and microstructural that will be described and discussed in this work

Comparação da eficiência térmica de trocadores de calor no laboratório de sistemas térmicos da Faculdade de Engenharia

This work aims to verify and compare the efficiency of heat exchangers used in the thermal systems laboratory at Faculdade de Engenharia do Campus de Guaratinguetá - UNESP. Basically, it has been studied two types of heat exchangers: plate type, operating in parallel flow and counter-flow, shell and tube type and also operating in parallel flow and counter flow. Initially it has been presented the didactic equipment and procedures for use of these heat exchangers in the proposed experiments. With the results obtained from the experiments, comparisons were made in order to define the behavior of the heat exchangers regarding some variables. In the study, one comes to the conclusion that the results from shell and tube type of heat exchanger, used in the thermal systems lab, are superior in all conditions analyzed

Avaliação do metabolismo oxidativo em cepas de Trypanosoma cruzi naturalmente resistentes ao benzonidazol

O agente etiológico da doença de Chagas, Trypanosoma cruzi, é responsável pela infecção de milhões de pessoas na América Latina. No momento há apenas dois fármacos disponíveis, o nifurtimox (5-nitrofurano), teve o uso descontinuado no Brasil, e o benzonidazol (2-nitroimidazole), embora ambos possuam ações limitadas, visto que dependem da fase da doença, das condições fisiológicas do hospedeiro, da suscetibilidade e variabilidade genética da cepa. Assim, a busca de novas moléculas torna-se urgente e necessária, bem como a compreensão do mecanismo de resistência aos fármacos tripanocidas. Alguns estudos relatam aumento na produção de enzimas que atuam na defesa celular, as quais, provavelmente, poderiam ser responsáveis pela resistência de certas cepas do parasita. Tais enzimas têm funções importantes na sobrevivência e crescimento dos parasitas: superóxido dismutase (SOD), uma metaloenzima que elimina radicais superóxido ao convertê-los em peróxido de hidrogênio e oxigênio molecular; old yellow enzyme (OYE), que é uma NADPH flavina oxidoredutase e pode estar envolvida na redução de substâncias tripanocidas; e, peroxiredoxina (Prx), que catalisa a redução de peróxidos. O objetivo deste projeto é avaliar a suscetibilidade de diferentes cepas ao benzonidazol, clonar, sequenciar e expressar enzimas possivelmente envolvidas na resistência a este fármaco e realizar análises morfológicas serão nos parasitos após serem expostos à substância em questão. Futuramente os anticorpos policlonais obtidos a partir das proteínas recombinantes de Prx, SOD e OYE serão empregados para avaliar o nível de expressão das mesmas em parasitas tratados e não tratados com o benzonidazol.

Caracterização microestrutural de uma estrutura tubular aeronáutica submetida a sucessivos reparos de solda TIG

This work examines the possible effects of successive repair procedures on the microstructure of welded steel SAE 4130 by TIG welding process. Discussions and results were made about the metallographic analysis , non-metallic inclusions and microhardness tests , which were conducted on samples taken from the cradle engine component after the end of its life , a model airplane T-27 Tucano , made by EMBRAER and belonging were performed FAB . The choice of such component is due to the fact that this is critical to flight safety since it provides support for the aircraft engine . Thus regions of the weld metal , base metal and heat affected , with samples of the original weld bead , free of weld bead and also with four rework procedures for TIG welding zone were analyzed . It was found that after the fourth rework there is an increase in the amount of martensite , which may weaken the material with respect to resistance to fatigue. It was also found that the regions of the heat affected zone and weld metal have higher microhardness values when compared to those found in the base metal due to favoring the formation of ferritic and tempered martensite microstructures . Moreover, a welding process promotes a region with less non-metallic inclusions than metal base , which also explains the difference in the results obtained

Análise da troca de calor em sistemas de injeção de termoplásticos – um estudo de caso: polipropileno

The purpose of this work was to define the processes through which the cooling of thermoplastics parts occur inside the mold cavity in an injection process. The plastic materials have become more widespread in the automobile industry and, among its manufacturing processes, injection moulding develops quickly, allowing the manufacturing of quality parts in great volumes. Data was collected from the injection of Volkswagen Gol NF 23X (Gol Generation 5). Using approximated methods for calculation for the heat Exchange inside the mould, in the cooling system, the required water flow was determined to properly cool the parts. Comparing the obtained value with Project specifications, it was verified that the method, in spite of incurring in some mistakes, is efficient in determining the flow of cooling fluid and serves as a verification tool for the parameters defined on project, and can be applied to simple projects. The definition of the cooling system, in practice, is dependent on innumerable variables and each case must be approached in itself, since the parameters for one product may not be ideal for another

Comportamento fractal de superfícies de fadiga em ligas aeronaúticas

Fracture surfaces express sequences of events of energy release with crack propagation in metal alloys, the evolution of topographic features can indicate the lines of load action, failures during the use or processing. The quantitative fractography is an important tool in the study of fracture surfaces, because it allows their interpretation and characterization. In order to evaluate the effectiveness of the characterization of fracture surfaces grounded on concepts such as selfsimilarity and self-affinity, it used the 15-5PH steel that was characterized by metallographic and tensile tests. The metallography allows the microstructural characterization of this steel and proved the presence of the martensite phase in the slats form and a fine-grained, both in the radial and in the axial direction of the dowel. The tensile test (ASTM E8) of this material allowed the determination of the mechanical properties, so based on the obtained results it was possible to affirm that the 15-5PH steel has high mechanical properties and a good stretch. Besides, the specimens also underwent testing of crack propagation, standardized by ASTM E647-00, thus it was obtained the fracture surfaces for characterization under monofractal and multifractal approaches. In front of all the exposed it was possible to conclude that in all measurements the correlation between the crack tip position and the fractal dimension was established in accordance with changes in the thickness and in the fracture micromechanisms presents. Furthermore, the multifractal approach was more sensitive to these variations allowing a more detailed characterization of the morphology

Análise macro e micrográfica da liga AA-356 conforme a taxa de resfriamento

The present work aims to study the characteristics of the alloy Al - 7 % Si - 0 , 3Mg ( AA356 ) , more specifically characterize the macrostructure and microstructure and mechanical properties of the alloy ingots AA356 obtained in metal molds and sand molds for power studying the structures through the difference of cooling rates . This alloy is explained by the fact of referring league has excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability , high wear resistance , high strength to weight ratio, has wide application in general engineering , and particularly in the automotive and aerospace engineering . In this work we will verify this difference in properties through two different cooling rates . We monitor the solid solidification temperatures by thermocouples building with them the cooling curve as a tool that will aid us to evaluate the effectiveness of the grain refining because it achieved with some important properties of the alloy as the latent heat of solidification fraction the liquid and solid temperatures, the total solidification time, and identify the presence of inoculants for grain refinement. Thermal analysis will be supported by the study of graphic software “Origin “will be achieved where the cooling curve and its first derivative that is the cooling rate. Made thermal analysis, analysis will be made in macrographs ingots obtained for observation of macrostructures obtained in both types of ingots and also analysis of micrographs where sampling will occur in strategic positions ingots to correlate with the microstructure. Finally will be collecting data from Brinell hardness of ingots and so then correlating the properties of their respective ingots with cooling rate. We found that obtained with cast metal ingots showed superior properties to the ingots obtained with sand mold

Diversidade genética em Staphylococcus aureus resistentes à oxacilina em isolados de pacientes pediátricos do Hospital das Clínicas de Botucatu

Staphylococcus aureus é um patógeno ubíquo capaz de causar uma variedade de infecções em humanos. A resistência desse microrganismo a antibióticos como oxacilina e meticilina é um problema sério, de crescimento significativo para a terapêutica antimicrobiana clínica em pacientes acometidos por infecções estafilocócicas. A resistência à meticilina em S. aureus é decorrente da alteração do sítio de ação dos antibióticos β-lactâmicos, os quais agem através da inibição de enzimas que catalisam a síntese da parede celular. Essas enzimas são o sítio de ação das penicilinas, e por isso, passaram a ser chamadas de proteínas ligadoras de penicilinas (PBPs). O gene mecA codifica a PBP2a, que substitui a função das outras PBPs neste patógeno e confere resistência a β-lactâmicos. A PBP2a exibe uma afinidade reduzida pelo anel β-lactâmico e permite que a bactéria continue a sintetizar a parede bacteriana. Este gene faz parte de um elemento genético móvel encontrado em isolados de MRSA, designado cassete cromossômico estafilocócico mec (SCCmec), integrado ao cromossomo de S. aureus. O objetivo do estudo foi a caracterização molecular de 139 isolados de S.aureus provenientes de pacientes pediátricos com bacteremia durante o período de 1991 a 2010. Métodos moleculares foram utilizados para a determinação do perfil genético das amostras, incluindo, identificação do tipo de SCCmec, detecção do gene codificador de leucocidina de panton valentine (PVL) e similaridade clonal em gel de eletroforese em campo pulsado (PFGE). O gene mecA foi detectado em 32 (23%) amostras e houve predomínio do SCCmec IV (68,8%) em relação ao SCCmec III (31,2%). A presença de PVL foi encontrada em 18 amostras (12,9%), todas sensíveis à oxacilina. O clone epidêmico brasileiro, relacionado ao SCCmec tipo III, esteve presente na unidade neonatal do hospital... (Resumo completo, clicar acesso eletrônico abaixo)

Triagem de substâncias antifúngicas com atividade inibitória de bombas de efluxo de isolados resistentes de Cryptococcus sp

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modelagem do equilíbrio térmico de frangos de corte: um estudo da geração e transferência de calor

Pós-graduação em Zootecnia - FCAV

Estudo do comportamento em fadiga das ligas AA6005, AA6063 e AA6351

Aluminum alloys have shown great potential for the automotive industry, especially aluminum alloys 6xxx series. This category has good mechanical strength and excellent corrosion resistance, important for the areas of construction and transport. The automotive industry has always shown great interest in the study of fatigue behavior, because structural components are subjected to cyclic and vibration loads, generating cracks and fracturing. The mechanical response depends on the material properties, applications, surface condition and microstructure. In this work was study the fatigue behavior of high cycle of machined bodies (not polished) and the effect of roughness on the fatigue life for three aluminum alloys of 6xxx series: AA6005, AA6351 and AA606, all in the T6 condition . S / N curves were made from fatigue tests in rotating bending (R = -1). The influence of roughness was studied by measuring the roughness of each specimen. Was compare the fatigue behavior of polished specimen and not polished specimens. The fractured surfaces of samples were observed by MEV, and it was observed that most of nucleation sites for fatigue crack is initiated below the surface