248 resultados para Bolted joints


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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Engenharia Mecânica - FEIS

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Experimental investigations were carried out using a Nd:YAG laser operating in pulsed mode for welding a lap joint between thin foil and thick sheet. The pulse energy was varied from 1.5 to 3.0 J at increments of 0.25 J with a 4 ms pulse duration. The base material used for this study was AISI 316L foils with 100 mu m thickness and sheet with 3.0 mm thickness. The welds were analysed by optical and electronic microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to join thin foil and thick sheet with good quality. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. The process appeared to be very sensitive to the gap between couples. Large voids delimited by the molten zone boundary were observed in joints welded with high pulse energy.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The aim of this study was to value the possibility to join, for pulsed Nd:YAG laser welding, thin foils lap joints for sealing components in corrosive environment. Experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser weld to examine the influence of the pulse energy in the characteristics of the weld fillet. The pulse energy was varied from 1.0 to 2.5 J at increments of 0.25 J with a 4 ms pulse duration. The base materials used for this study were AISI 316L stainless steel and Ni-based alloys foils with 100 mu m thickness. The welds were analyzed by electronic and optical microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to thin foil weld quality because it can generate good mechanical properties and reduce discontinuities in weld joints. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. In all the specimens, fracture occurred in the top foil heat-affected zone next to the fusion line. The microhardness was almost uniform across the parent metal, HAZ and weld metal. A slight increase in the fusion zone and heat-affected zone compared to those measured in the base metal was observed. This is related to the microstructural refinement in the fusion zone, induced by rapid cooling of the laser welding. The process appeared to be very sensitive to the gap between couples.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Taekwondo practice has been associated with physical and biomechanical overloads, which are related to occurrence of sports injuries (SI). However, etiological and nosographic information about SI are limited and conflicting. This study analyzed and characterized the SI in Taekwondo athletes, according to gender. Casuistic integrated 22 athletes, 12 men and 10 women, athletes from São Paulo State Team of Taekwondo, adult category, with 23,6±6,8 years, body weight of 66,0±13,1 kg and 1,72±0,09 m of height. Reported morbidity survey was used to obtain retroactive information to 2009 season. Nosographic variables were analyzed using Goodman’s Test for contrasts among multinomial populations. All athletes reported injuries in the season; 56 cases were registered, determining an injury rate of 2.54 SI/athlete; 26 events (46.4%) occurred in males (2.17 SI/athlete), and 30 (53.6%) were related to women (3.00 SI/athlete). There were predominance of injuries in joints (35,7%) and muscles (39,3%); both genders presented injuries in lower members (82.1%, p<0.01), predominant in combat situations (80.4%, p<0.05), during the preparatory period of training (73.2%). There was a higher treatment request among male athletes (73.1%), which showed high asymptomatic return (69.2%); the female group referred similar proportions of absence and presence of treatment request, collaborating for the greater symptomatic return of these athletes (70.0%). In conclusion, the results support predominance of muscles and joints injuries in lower segments, derived from fighting, involving female athletes.

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This article portrays Supervised Curricular Training experiences in Paulistas Universities by means of learning portfolios. The reflections presented indicate the pathways of experiences with this feature didactic-pedagogical motivator of qualitative advances in cultural formation of students and teachers of the Pedagogy Course. The methodological approach was chosen for consistent in the defense of necessary joints of dialogical, reflexive and emancipatory dimensions in training teachers for Early Childhood Education, and to contribute in the mediation of the activities carried out by undergraduates, with individualized follow in the formation of each one of them. The experience, stand out learnings regarding limits of this practice and the significant advances realized in each student, by means of their written work, sharing of knowledge, the interlocution between them and the teachers and the link with theory and practice through the Internship Supervised and the use of learning portfolios.