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- Aluminum-to-Steel Cladding by Explosive WeldingPublication . Carvalho, Gustavo H. S. F. L.; Galvão, Ivan; Mendes, Ricardo; Leal, Rui M.; Loureiro, AltinoThe production of aluminum-carbon steel and aluminum-stainless steel clads is challenging, and explosive welding is one of the most suitable processes to achieve them. The present work aims to investigate the coupled effect of two strategies for optimizing the production of these clads by explosive welding: the use of a low-density interlayer and the use of a low-density and low-detonation velocity explosive mixture. A broad range of techniques was used to characterize the microstructural and the mechanical properties of the welds, specifically, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, microhardness and tensile-shear testing with digital image correlation analysis. Although aluminum-carbon steel and aluminum-stainless steel have different weldabilities, clads with sound microstructure and good mechanical behavior were achieved for both combinations. These results were associated with the low values of collision point and impact velocities provided by the tested explosive mixture, which made the weldability difference between these combinations less significant. The successful testing of this explosive mixture indicates that it is suitable to be used for welding very thin flyers and/or dissimilar materials that easily form intermetallic phases.
- 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.
- Co-designing new resources to support better quality end of life care with people with dementia and family carersPublication . Macdonald, Alastair; Neves, Sandra; McLellan, Emma; Poole, MarieAs more people die with dementia, end of life care discussions are growing in importance. Alastair Macdonald and colleagues report on their study and explain how co-designing new resources could help to strengthen support at the end of life
- Desenhos animados e narrativa sequencial para crianças Surdas – Procurando comunicar, entre ouvir e visualizarPublication . Marques, Nuno fragata; Conde e Sousa, Joana; Esteves Rodrigues, AndreiaOs desenhos animados são uma forma de entretenimento apreciada por crianças e adultos em todo o mundo e desempenham um papel significativo no desenvolvimento cognitivo, emocional e social das crianças. Iremos procurar relacionar a criação de desenhos animados gestuantes em diálogo com formas de narrativa sequencial, a banda desenhada e o storyboard, como comunicação direcionada a dois públicos distintos, crianças surdas e crianças ouvintes. Partimos de um ponto de vista inclusivo que as coloca em ponto de igualdade como público-alvo a favor da identificação de pistas que ajudem à criação de narrativas e conteúdos em cinema de animação. Exploraremos a importância dos desenhos animados para crianças Surdas, fonte de acessibilidade linguística, estímulo visual e cognitivo, representação e educação. Por meio de um estudo exploratório, via pesquisa, análise e produção, procura-se perceber possibilidades visuais para explorações da representação do som. Apresentamos, como resultados, um conjunto de considerações a seguir a favor da criação de desenhos animados gestuantes, representativos da cultura surda.
- Drawing powersPublication . Poeiras, Fernando
- 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.
- Effect of explosive ratio on explosive welding quality of copper to aluminiumPublication . Loureiro, A.; Mendes, R.; Ribeiro, J. B.; Leal, R. M.The goal of this research is to study the influence of the ratio of an explosive composed of 80% ANFO and 20% matrix on the quality of dissimilar explosive welds of Cu-DHP copper to aluminium alloy 5083-H11, in flat configuration. It is analysed the influence of four explosive ratios (1.4, 1.8, 2.3 and 2.6) on the microstructure and mechanical properties of welds. It was observed that the increase in the explosive ratio gives rise to an increase of the collision point velocity (Vc) and the impact velocity (Vp) and consequently reduces the thickness of the flying plate after welding as well as produces wavy interfaces of greater amplitude. Microstructural analysis showed the formation of hard and brittle intermetallic compounds in the interface region, more obvious in welds made with higher ratio of explosive.
- 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.
- Effect of shoulder cavity and welding parameters on friction stir welding of thin copper sheetsPublication . Leal, R. M.; Sakharova, N.; Vilaça, P.; Rodrigues, D. M.; Loureiro, A.The aim of this investigation was to study the influence of shoulder cavity and welding parameters on torque, defect formation, microstructure and mechanical properties of friction stir welds in very thin sheets of deoxidised copper. Three types of tools were used: a flat shoulder tool and two tools with conical shoulder cavities of 3 and 6° respectively. The welding parameters analysed were tool rotation and traverse speeds. It was observed that the torque, the microstructure and hardness and the formation of defects in the welds are influenced mainly by tool rotation speed and, to a lesser extent, by the traverse speed and shoulder cavity. The tensile properties of welds carried out at high rotation speeds are little affected by the shoulder cavity.
- 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.
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