Estudo da fadiga em liga de alumínio aeronáutico 7475-T761

This work will address the study of fatigue conditions with constant load in an alloy of aluminum analysis 7475 - T761, so we can better understand the conditions of the aircrafts which contain this alloy in their structures. A literature review, which was discussed the concepts of fracture mechanics, fatigue, aeronautical components, chemical analysis of aluminum alloys, fatigue problems that appears in the aircrafts, metallographic analysis, and testing of optical microscopy tensile, fatigue and microhardness, surface analysis (MEV) study of the chemical composition of the alloy in question, the main causes of crashes, was performed, completing the work, analysis of data from tensile test, hardness and fatigue together with the interpretation of images of optical microscopy and scanning electron was taken. The data indicated the high mechanical strength of the alloy, along with its microstructure indicating elongated grains and high surface contour, which shows such resistance by hindering the movement of dislocations. The grooves are clearly shown in the MEV images as well as the classic with increased fatigue loading and subsequent reduction of the number of cycles to rupture behavior shown in the graphs. Therefore we observed the optimal behavior is supported by the league when subjected to fatigue loadings

Estudo do comportamento em fadiga de um tubo de aço microligado, grau API 5L X70

This work focuses on a study on the fatigue behavior of a microalloyed steel API 5L X70, used in pipes lines to transport oil and gas. These types of steels have excellent mechanical resistance values and ductility and therefore increased their study driven by increased demand for oil and especially natural gas, which consequently raises the need to build new pipelines to transport these products. The oil extraction units, composed of the risers (pipelines connecting the oil well to the ship), are dimensioned to remain installed for periods of 20 to 30 years in the marine environment, a hostile environment for high pressure, corrosion, low temperatures and the stresses caused by the movement of water and tides. For analysis, the S-N (stress versus number of cycles) curves were obtained from data collected from bodies-of-proof cylindrical longitudinal, transverse and that one removed from the weld area of the pipe, tested in accordance with ASTM E466. Tensile tests were performed for characterizing the mechanical properties of the samples and welded joints, concluded that the values meet the specifications of the standard API 5L. To characterize microstructural material, also metallographic analysis was made of regions of the base metal and the HAZ. The results of fatigue tests demonstrated a higher life for the specimens removed from the longitudinal direction the pipe, followed by those in the transverse direction and, finally, the welded joint. The origins of the fatigue cracks were determined by scanning electron microscopy (SEM)

Técnicas de caracterização microestrutural, por microscopia óptica e microscopia eletrônica de varredura, de aços bifásicos e multifásicos aplicados à indústria automobilística

This project developed microstructural characterization technics of commercial dualphase and multi-phasic (TRIP) steels that were provided by the automotive industry and are currently used as the raw material for the production of automobiles. Inserted in this context, there is the development of the advanced high strength steels in consonance with the ULSABAVC project, which aims the production of safe, economically viable and efficient in terms of fuel consumption vehicles for the 21st century. The micro-structural characterization of biphasic and multiphase steels was done by the identification and quantification of the coexistent phases. In this item, a special attention was given to the technics that were performed using optic microscopy and scanning electron microscopy. An important contribution to this work was the utilization of different alternative chemical reagents (Beraha, Heat-Tinting technics) in addition to the classical ones (Nital and LePera)already used conventionally by the UNESP's Group of Mechanical, Microstructural and Fractografic Characterization of Materials. The revealed microstructures were correlated with the materials' mechanical properties determined through traction tests, such as ultimate tensile strengths, yield strength and stretching important since the material has structural application in the automotive industry. As a result, it was observed the superiority concerning the studied mechanical properties for the biphasic and multiphasic steels when compared to the conventional carbon steels. Besides, it was perceived a large potential for the industrial scale utilization of the Heat Tinting technics in this field, seen its differentiation of the existent phases and easy reproducibility

Desenvolvimento de um novo sistema dinâmico para avaliação da liberação de fármacos

Pós-graduação em Biociências - FCLAS

Aplicação da membrana de látex natural (NRL) como suporte para cultura das células osteogênicas MC3T3-E1 para regeneração óssea guiada (GBR)

Pós-graduação em Biotecnologia - IQ

Análise de blocos de concreto com resíduo de borracha de pneu e metacaulim

Pós-graduação em Engenharia Civil - FEIS

Monitoramento de danos estruturais utilizando sensores de nanocompósitos

Pós-graduação em Engenharia Mecânica - FEIS

A palavra poética de Arnaldo Antunes

This article reflects on Arnaldo Antunes‟ (AA) poetics. For this purpose, both the contributions of Fontanille and Zilberberg regarding tensivity, as well as some ideas of Tatit regarding song semiotics. The aim is to think about how the dance between enunciation and enunciate is structured in AA within poetical architecture as exemplified here based on the analysis of the poem “Palavra”. The hypothesis is that the tension between the two central nuclei of the poem, metalanguage and erotism, are the essential compositional marc of AA poetical stylistics. The results lead to the reflection that the musical tension is the game that guarantees the movement between the density of the word and the erotic fluidity of the authorial (metalinguistic) act of production.

Gonçalves Dias, o índio e a liberdade

This article presents a reading of the poem “O canto do guerreiro” written by Antonio Gonçalves Dias. The aim is to show the existence of a dialogue between the literary‘representation of the Brazilian‘indigenous and the concept of natural man, by Jean Jacques Rousseau. Going beyond a reading upon a romantic nationalism view, such dialogue makes explicit the poet’ conscience of his hole in Brazilian Romanticism and, at same time, gives a universal dimension to his poetic work.

Effect of ultrasonic ecxitation on the ultimate tensili strength of glass ionomer cements after different water storage times

The application of ultrasound waves with a conventional dental ultrasonic scaler on glass ionomer cements surface accelerated initial setting reaction and improved the mechanical properties. Objective: This study evaluated the ultimate tensile strength of glass ionomer cements after ultrasonic excitation and different water storage times. Material and method: Twelve specimens of each material (Fuji IX GP, Ketac Molar Easymix and Vitremer) were prepared, and six of each received a 30-second ultrasound application during initial setting of the cements. After storage of the 24 hours or 30 days, the specimens were sectioned into stick to microtensile testing and the mean ultimate tensile strength values were submitted to Welch’s ANOVA and Tamhane’s test. Result: The results showed that the Vitremer presented the highest mean tensile strength. The chemically set Fuji IX GP presented significantly higher mean tensile strength after 30 days than after 24 hours of storage (p < 0.05). At 24 hours, the ultrasonically set Fuji IX GP presented significantly higher mean tensile strength than their counterparts set under standard conditions (p < 0.05). Conclusion: Treatment with ultrasound increased the tensile strength of Fuji IX GP in the early period of maturation.

Degradação de forças dos elasticos intermaxilares ortodônticos sintéticos

This study aimed to evaluate the force degradation of synthetic elastics over time using dynamic biomechanical tests in order to find clinical parameters of what size of elastic and frequency of exchange should be used in orthodontic therapy. It was used 240 elastics of Dental Morelli, sizes 1/8", 3/16", 1/4 "and 5/16", medium force, divided in four groups. In each group was measured forces at different times, from immediate to 72 hours after immersion in water at 37°C and incubated stretched to 600% of its initial inner diameter. Tensile tests were performed on a universal testing machine EMIC DL2000 submerged in distilled water maintained at 37°C. Data were analyzed using SPSS version 16.0, by the Analysis of Variance (One-Way) with Tukey´s post test. There was a greater increase in pattern of force decay of immediate measurement until 24 hours in all sizes of synthetic elastics, from which it was observed a decrease in force progressively smaller, with the exception of 5/16´´ elastic with a maximum force decay occurred at 12h. It was concluded that: the elastic synthetic Dental Morelli suffered significant force degradation over time, with reduction of approximately 70% of the initial force during 24 hours of stretching, followed by a progressively smaller decrease; the amount of stretch for a ideal force in intermaxillary therapies depends on the distance between the points of attachment of elastic, being necessary to consult the tables to choose the size, force and frequency of replacement.

Herbst esplinte metálico fundido: novo modelo de confecção com Duralay

A má oclusão de Classe II é originária de vários fatores etiológicos e uma das características mais comum desta má oclusão é a retrusão mandibular3, por esse motivo, os aparelhos de avanço mandibular são eleitos para o tratamento e correção desta má oclusão. Um destes aparelhos é o Herbst, que apresenta várias formas de ancoragens na sua confecção10. Tradicionalmente, as bandas eram o sistema de ancoragem mais usado, no entanto, pela alta frequência de quebras as mesmas foram substituídas por esplinte metálico12. Esse aparelho quando confeccionado de cromo cobalto pelo método da prótese parcial removível, apresenta como desvantagens a quantidade de passos laboratoriais e a possível contração do metal, podendo ocasionar a má adaptação da estrutura metálica à boca do paciente. Dessa forma, este artigo apresenta um novo método de confecção do aparelho de Herbst esplinte metálico fundido com uso da Duralay e liga níquel cromo. Esse método diminui os passos laboratoriais, proporciona maior resistência à tração e minimiza a contração da estrutura metálica, pois a resina química Duralay proporciona menor expansão do que a cera2.

Tratamento da má oclusão de classe II, divisão 1, na dentadura mista com apareljo extrabucal removivel

Extraoral appliances represent an alternative for correction of Class II malocclusions. The application of external force leads to tooth movement and influence the growth of the maxillomandibular complex. This article aims to present the removable headgear as an adjuvant in the treatment of Class II division 1 in the mixed dentition.

Efeito de um gel de peróxido de carbamida a 10% sobre a resistência de união de restaurações adesivas à dentina

The present study aimed to analyze the effects of tooth bleaching with 10% carbamide peroxide (CP) gel on the bond strength of resin composite restorations to dentin. Material and Methods: Twenty cavities were prepared on the buccal surface of bovine teeth. After acid etching and application of bonding agent on dentin and enamel, the cavities were restored with composite resin. The specimens were divided into groups according to treatment on the surface of enamel / restoration: G1 - control (no treatment) and G2 (10% PC gel application for 8h/day during 14 days). After this period, the teeth were cut to produce beams with 0.81 mm2 cross-sectional area, which were subjected to microtensile test. The fractures were examined with a stereomicroscope and classified as cohesive in resin or dentin, adhesive, or mixed. Results: The statistical analysis (ANOVA / χ2) revealed that the factor treatment interfered with the bond strength, which was significantly higher for specimens of G2 (p <0.05). Adhesive fractures occurred in most of specimens of both groups with values ranging from 48.3% to 75%. Mixed fractures were the second more frequent in G1 and cohesive resin failure in G2. Conclusion: It was concluded that tooth bleaching with 10% of PC increased the bond strength of adhesive restorations to dentin.

Associação de facetas diretas e fibra de reforço para restabelecimento estético do sorriso: relato de caso clínico

Esse artigo tem como objetivo demonstrar o restabelecimento estético do sorriso obtido por meio da associação de facetas diretas e fibra de reforço. As fibras de reforço são utilizadas como alternativa para substituição de elementos dentários perdidos e possuem indicações precisas, sendo empregadas em diversas especialidades da Odontologia, devido à sua capacidade de aumentar a resistência à tração dos compósitos, o que aumenta a resistência à compressão das fibras. Para o completo restabelecimento do sorriso, muitas vezes é necessário reanatomizar os dentes adjacentes, considerando as condições em que esses se apresentam. Sendo assim, o profissional deve ter conhecimento para aplicação correta da técnica e restabelecimento da estética ao paciente.