ESAD.CR - Artigos em revistas internacionais
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- Mechanical behaviour of similar and dissimilar AA5182-H111 and AA6016-T4 thin friction stir weldsPublication . Leitão, C.; Leal, Rui; Rodrigues, D.M.; Loureiro, A.; Vilaça, P.The tensile behaviour of similar and dissimilar friction stir welds in 1 mm thick sheets of two aluminium alloys (AA5182-H111 and AA6016-T4) is analysed in this paper. The heterogeneity in properties across the welds was studied by performing microhardness tests and microstructural analysis. The tensile tests were performed in samples extracted longitudinal and transverse to the weld direction. It was found that the tensile behaviour of the welds depends mainly on the grain size in the TMAZ, for the AA5182-H111 alloy, and on precipitate distribution, for the AA6016-T4 alloy. In all types of welds, the HAZ preserves the same properties of the base materials. The global mechanical behaviour of the AA5182-H111 similar welds is very similar to that of the base material. However, for the AA6016-T4 similar welds and for the AA6016-T4-AA5182-H111 dissimilar welds a 10-20% strength reduction relative to the base materials and important losses in ductility were reported.
- Influence of friction stir welding parameters on the microstructural and mechanical properties of AA 6016-T4 thin weldsPublication . Rodrigues, D.M.; Loureiro, A.; Leitão, C.; Leal, Rui; Chaparro, B.M.; Vilaça, P.In present work friction stir welds produced in 1 mm thick plates of AA 6016-T4 aluminium alloy, with two different tools, were analysed and compared concerning the microstructure and mechanical properties. For each tool, the welding parameters were optimized in order to achieve non-defective welds. Assuming a relation between the welding parameters and the energy input per unit of length of the weld [Seidel TU, Reynolds AP. Visualization of the material flow in AA2195 friction stir welds using a marker insert technique. Metall Mater Trans A 2001;32A:2879-84; Sato YS, Urata M, Kokawa H. Parameters controlling microstructure and hardness during friction stir welding of precipitation-hardenable aluminum alloy 6063. Metall Mater Trans A 2002;33(3):625-35; Lim S, Kim S, Lee CG, Kim S-J. Tensile behavior of friction-stri-welded Al 6061-T651. Metall Mater Trans A 2004;35(9):2829-35; Yang B, Yan J, Sutton MA, Reynolds AP. Banded microstructure in AA2024-T351 and AA2524-T351 aluminum friction stir welds: Part I. Metallurgical studies. Mater Sci Eng A 2004;364(1-2):55-65; Peel MJ, Steuwer A, Withers PJ, Dickerson T, Shi Q, Shercliff H. Dissimilar friction stir welds in AA5083-AA6082. Part I: process parameter effects on thermal history and weld properties. Metall Mater Trans A 2006;37:2183-193; Gerlich A, Su P, Yamamoto M, North TH. Effect of welding parameters on the strain rate and microstructure of friction stir spot welded 2024 aluminum alloy. J Mater Sci 2007;42(14):5589-601; Lombard H, Hattingh DG, Steuwer A, James MN. Optimising FSW process parameters to minimise defects and maximise fatigue life in 5083-H321 aluminum alloy. Eng Fract Mech 2008;75(3-4):341-54], the welds produced were classified as "hot" and "cold welds". The results obtained showed that the "hot" welds, obtained with the maximum tool rotational speed and the minimum traverse speed, have improved mechanical properties relative to the "cold" welds that were in undermatch condition relative to the base material. The differences in mechanical properties between the two types of welds are explained based in TEM microstructural analysis. Despite the undermatched characteristics of the "cold" welds relative to the base material, formability tests demonstrated that these welds improve the drawing performance of the welded sheets.
- Bio Art meets the streets : a reflection on new forms of art engagementPublication . Santos, David Rodrigues dosPublic art, despite is extension to the urban landscapes, has been a limited artistic practice in terms of critical discussion. In this sense, is has been used as an urban form for remodelling or, instead, as an ordinary form of expansion of the artists audience. However, public art can be understood as a social awareness practice creating the need to set up a broader critical discourse contributing to a greater democratization to the artistic practice. In this sense, there has been a growing number of visual artists who believe that art and the role of public entities isn’t just the creation of permanent art objects, but rather a way to facilitate the creation of artworks that encourage actions, ideas and the intervention of the audience, making the public artwork an object that calls to social responsibility. Bio art has tried to demonstrate, through its aesthetic discourse, the need to establish a broader public discussion. Thus, in this paper we will highlight the importance of an odd art public project of Natalie Jeremijenko – One Tree(s) (2000). Through the questions raised by this artwork, we will reflect on how the intersection between art and technoscience can contribute to a greater extension of the idea of hard humanities and on how a larger critical reflection can be exercise through and beyond the art world toward a field that involves in the same discourse art, science, society and the urban network.
- Le rappeur et les «petites grandmères»: Deux ethnographies du cosmopolitisme comme médiationPublication . Fradique, TeresaComment aborder le cosmopolitisme en ce début de siècle ? Peut-on déjà en dégager des contours nouveaux ? À partir des propositions de certains textes et concepts de l’anthropologue brésilien Gilberto Velho, l’idée d’un cosmopolitisme se détachant de son opposition binaire avec le provincialisme est explorée. Deux cas ethnographiques très différents sont à l’étude : l’un repose sur l’univers urbain du rap ; l’autre, sur une expérience artistique menée auprès d’une communauté périphérique. Ici le cosmopolitisme, plus qu’un style de vie, est l’action d’un spécialiste en mouvement, d’un médiateur qui encourage le changement des statuts, des contextes culturels et, conséquemment, des visions du monde.
- Effect of friction stir processing parameters on the microstructural and electrical properties of copperPublication . Leal, Rui; Galvão, I.; Loureiro, A.; Rodrigues, D. M.Friction stir processing (FSP) is an innovative technology, based on friction stir welding (FSW) operative principles, which can be used for changing locally the microstructure and the mechanical properties of conventional materials. In this work, the copper alloy C12200 was friction stir processed using two distinct tools, i.e. a scrolled and a conical shoulder tool, in order to promote different thermomechanical conditions inside the stirred volume, and consequently, varied post-processed microstructures. The influence of the tool geometry and tool rotation and traverse speeds on the microstructural and electrical properties of the processed copper alloy was analysed. The processing conditions were found to have an important influence on the electrical conductivity of the processed material. The differences in electrical conductivity were explained based on dislocations density effects. The effect of the dislocations density on electrical conductivity of the processed material was found to prevail over the effect of the grain boundaries.
- Thermic Fits: fatos de hidroginástica para idososPublication . Bispo, Renato; Daré, Ana; Francisco, AndreaO projeto Thermic Fits parte do pressuposto que a atividade física tem um papel fundamental para o envelhecimento bemsucedido e para a promoção da saúde, autonomia e a autoconfiança da população idosa. A hidroginástica foi a atividade escolhida, por apresentar já alguma adesão por parte das pessoas idosas em Portugal, manifestando, contudo, ainda alguns problemas por resolver, nomeadamente: sentimentos de vulnerabilidade e vergonha provocados pela utilização do fato de banho, desconforto provocado pela temperatura da água, dificuldade em vestir e despir e desadequação antropométrica relativamente à diversidade corporal que se verifica neste segmento da população. Durante o projeto, foram realizados entrevistas e testes no Centro Social Paroquial de Nossa Senhora das Mercês de Carvalhal Benfeito e na Associação Humanitária dos Bombeiros Voluntários das Caldas da Rainha (Portugal), o que permitiu que modelos funcionais dos fatos de banho tivessem sido continuadamente testados, por pessoas idosas, durante várias fases do seu desenvolvimento. Este projeto foi desenvolvido no âmbito do Mestrado de Design de Produto da Escola Superior de Artes e Design do Instituto Politécnico de Leiria [ESAD.CR].
- Um percurso mediativo por algumas florestas na artePublication . Rama, Samuel José TravassosA grande floresta europeia densa e obscura desapareceu proporcionalmente ao crescimento das cidades sobretudo a partir da modernidade. Na mesma medida do desaparecimento das florestas reais dá-se o seu incremento no território da cultura em geral e nas artes plásticas em particular. A floresta assume-se assim como arquétipo ou índice do natural e é nos seus melhores exemplos da arte sempre revisitada por uma persistente expressão atravessada pelo sonho e pela nostalgia. Nas representações de florestas feitas por artistas que quiseram recuperar, do pondo de vista estético, estas paisagens a partir de dentro, podemos encontrar talvez uma das raízes mais longínquas do questionamento ou da relativização da ideia de paisagem enquanto vista ou janela, a favor de uma ideia de paisagem enquanto errância ou envolvimento. Esse questionamento parece trazer também consigo a expressão ou tradução do fundamento ético primeiro que faz reconhecer a natureza como algo absolutamente superior ao homem. Tal acontece porque a maioria das representações de florestas feitas a partir do seu interior revelam um certo carácter estético negativo que induz no espectador mobilidade, desconforto, estranhamento obrigando-o a indagar e articular juntamente estética e ética.
- Effect of explosive mixture on quality of explosive welds of copper to aluminiumPublication . Loureiro, A.; Mendes, R.; Ribeiro, J.B.; Leal, Rui; Galvão, I.The aim of this research is to investigate the influence of explosive ratio and type of sensitizer on the quality of explosive welds between copper and aluminium alloy plates. The welds were performed on a partially overlapping joint configuration using an emulsion explosive (EE) with two different sensitizers, hollow glass microspheres (HGMS) and expanded polystyrene spheres (EPS). Welds with an improved surface were achieved by using the HGMS sensitizer. A higher wave amplitude was registered in welds produced with the EPS sensitizer. In turn, the dimension of the molten pockets was influenced by the explosive ratio, increasing in size with increases in the values of this parameter. The intermetallic content of these zones varied according to the sensitizer type.Unlike the CuAl2 phase, the Cu-richer phases CuAl and Cu9Al4were only identified inwelds performed using the EPS sensitizer. An increase in hardness was observed at the interface of all welds, which resulted from both the presence of intermetallic phases and the plastic deformation of the materials promoted by the impact. This effect was most evident on the aluminium alloy side. All the welds had a greater strength than copper, i.e. the weakest material of the joint.
- The many faces of a face: Comparing stills and videos of facial expressions in eight dimensions (SAVE database)Publication . Garrido, Margarida V.; Lopes, Diniz; Prada, Marília; Rodrigues, David; Jerónimo, Rita; Mourão, Rui P.This article presents subjective rating norms for a new set of Stills And Videos of facial Expressions—the SAVE database. Twenty nonprofessional models were filmed while posing in three different facial expressions (smile, neutral, and frown). After each pose, the models completed the PANAS questionnaire, and reported more positive affect after smiling and more negative affect after frowning. From the shooting material, stills and 5 s and 10 s videos were edited (total stimulus set = 180). A different sample of 120 participants evaluated the stimuli for attractiveness, arousal, clarity, genuineness, familiarity, intensity, valence, and similarity. Overall, facial expression had a main effect in all of the evaluated dimensions, with smiling models obtaining the highest ratings. Frowning expressions were perceived as being more arousing, clearer, and more intense, but also as more negative than neutral expressions. Stimulus presentation format only influenced the ratings of attractiveness, familiarity, genuineness, and intensity. The attractiveness and familiarity ratings increased with longer exposure times, whereas genuineness decreased. The ratings in the several dimensions were correlated. The subjective norms of facial stimuli presented in this article have potential applications to the work of researchers in several research domains. Fromour database, researchers may choose the most adequate stimulus presentation format for a particular experiment, select and manipulate the dimensions of interest, and control for the remaining dimensions. The full stimulus set and descriptive results (means, standard deviations, and confidence intervals) for each stimulus per dimension are provided as supplementary material.
- Effect of the flyer material on the interface phenomena in aluminium and copper explosive weldsPublication . Carvalho, G.H.S.F.L.; Mendes, R.; Leal, R. M.; Galvão, I.; Loureiro, A.The effect of physical and mechanical properties of three different flyers on the interface phenomena of partially overlapped explosive welds, using the same base plate material, was studied. Flyers of Copper Cu-DHP and aluminium alloy 6082 (tempers T6 and O) were welded to AA6082-T6 base plates. The morphology of the weld interface is strongly influenced by the physical and mechanical properties of the flyer. In the interface of the aluminiumwelds, the use of a flyer of lower hardness and yield strength than the base plate results in asymmetrical waves, with bigger amplitude and smaller wavelength than the weld series of similar temper, and higher mechanical properties. The copper-aluminium welds presented flat interfaces, mainly because of the significant differences inmelting temperature and density between the copper flyer and the aluminiumbase plate. Considering these results and analysing several dissimilar welds carried out by other authors itwas found thatwhen the product of density and melting temperature ratios between the flyer and the base plate exceeds a certain value, there is no formation of waves at the interface of the metals. Furthermore, for the Cu-Al welds, the CuAl2 (θ) intermetallic phase was formed on the bond zone.