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- Mechanical caracterisation of polyester resin and corn natural fibers compositePublication . Queijo, Luis; Rocha, JoãoThe use of natural fibers as reinforcement in polymer matrix composites is gaining popularity in the development of renewable products. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. The work deals with the characteristics of fiber composites that can offer several advantages, like low cost, weight savings and relatively good mechanical properties. It focuses on the effects of corn fibers as reinforcement agents in composites. Mechanical testing was performed to qualify the reinforcement properties of the corn fibers and consequently to compare with fiberglass composites.
- Application of the STEAM methodology for laser scanning of historic buildingsPublication . Carvalho, H.C.L.; Santos, Jorge; Lopes, Isabel Maria; Ribeiro, J.E.; Rocha, João3D laser scanning ensures consistency and objective validation of results, further increasing the level of quality and advancing problem resolution. Combining the scanner output with auxiliary programs, the scanned images become electronic mockups. This type of technology allows low-access environments to be integrated into the collection, as well as specific objects, maintaining their integrity and allowing the researcher to work virtually avoiding losses. Contributing to the guarantee of historic buildings, the study is focused on the development of a new methodology to identify the pathology and assist in the restoration of heritage.
- Mechanical properties of PLA specimens obtained by additive manufacturing process reinforced with flax fibersPublication . Paulo, Ana; Santos, Jorge; Rocha, João; Lima, Rui A.; Ribeiro, J.E.Abstract Although polylactic acid (PLA) is one of the most used materials in additive manufacturing, its mechanical properties are quite limiting for its practical application, therefore, to improve these properties it is frequent to add fibers and, in this way, create a more resistant composite material. In this paper, the authors developed PLA composites reinforced with flax fibers to evaluate the improvement of tensile and flexural strength. The experimental design of experiments was based on the L18 Taguchi array where the control factors were the extruder temperature (three levels), number of strands (three levels), infill percentage of the specimens (three levels), and whether the flax fiber had surface chemical treatment. The tensile and flexural specimens were made on a 3D printing machine and was a mold was developed to fix and align the fiber strands during the printing process. The tensile and flexural experimental tests were performed in agreement with ASTM D638.14 and ISO 14125 standards, respectively. Analyzing the results, it was verified that the surface chemical treatment (NaOH) of the fiber did not show any influence in the mechanical properties of the composites; in contrast, the infill density demonstrated a huge influence for the improvement of mechanical strength. The maximum values of tensile and bending stress were 50 MPa and 73 MPa, respectively. The natural fiber reinforcement can improve the mechanical properties of the PLA composites.
- Mechanical characterisation of cytisus scoparius natural fibres – a preliminaryPublication . Queijo, Luis; Rocha, João; Ribeiro, J.E.The use of natural fibres as reinforcement in polymeric matrix composites is gaining popularity sustained not only by a logical search of more ecological alternatives to the conventional fibres in the development of renewable products but also by economic reasons. Although the conventional glass and other synthetic fibre-reinforced plastics possess high specific strength, their fields of application are limited because of their inherent higher production cost and their lack of recycling possibilities. The use of natural fibres from autochthones plants without commercial value for “green” composites production should be enhanced once the higher value-in-use may mean increasing the content of a local material (a natural fibre) in the local production of a part (a composite) [1]. This work’s objective is to provide one first approach to mechanical characterisation of scotch broom (Cytisus Scoparius) natural fibres in order of its future use in natural fibre reinforced composites production. Fibres to be tested have been extracted from year scotch broom branches using traditional techniques that consisted in smashing the branches, a maceration period, rip them to remove the soft organic tissue and then naturally dry the obtained fibres. For natural fibres characterisation was develop a special mounting frames to allow them to be essayed according the ASTM D2343 – 09 standards [2]. From the extracted data in yield strength tests over scotch broom fibres it can be concluded that those represent a promising complimentary choice to other natural fibres in natural fibre reinforced composites manufacturing, whose application can be settled as medium strength appliances. Also, usually local non-valuable resource is explored contributing to forest residues cleaning with added benefits. This works is being followed by polymeric composite plates production, using these fibres, with a random orientation, as a first approach, and then with usual defined orientations and its testing in order to realise which mechanical characteristics can be expected as a composite.
- Use of a fab lab in STEAM education : development of information technologies inserted in a smart city context through a fablabPublication . Souza, Renato Costa de; Rocha, João; Lopes, Isabel Maria; Rocha, Catarina; Carvalho, John Maico Godoi deDois conceitos muito disseminados ao redor do globo tornaram-se obsoleto, os conceitos de cidades como as conhecemos atualmente, com demasiada exploração dos recursos naturais existentes e o conceito de educação, onde ainda se ensina como no século passado. Embora haja novas ferramentas capazes de melhorar esse cenário, como as tecnologias de informação em comunicação (TIC), elas ainda são pouco utilizadas para adequação desses conceitos à realidade em que vivemos hoje. Para isso, novas maneiras de pensar as cidades e o ensino vêm surgindo. As smart cities, o modelo de educação STEAM, as TIC's e os laboratórios de fabricação digital (fab labs), podem ser uma combinação poderosa no desenvolvimento e implementação de tecnologias capazes de ajudar nessa transição.
- Desenvolvimento de um simulador de laparoscopiaPublication . Monteiro, Stéphanie; Vilas Boas, Liliana da Silva; Rocha, João; Novo, AndréCom base no simulador de laparoscopia existente no hospital de Bragança foi proposto o desenvolvimento de um novo que incluísse novas formas de manuseamento e que incluísse atratividade para tornar o treino dos profissionais mais preciso. Exteriormente, a portabilidade foi assegurada pela escolha de uma mala leve e compacta, que permite não só a arrumação mas o transporte para a sala de simulação ou até para um local diferente do de origem. Esta mala, pintada de branco para uma melhor deteção de sujidades, é o próprio simulador, sendo adaptada para diferentes alturas consoante o treino exigido ao profissional de saúde. Na sua tampa foram realizados três furos, dois para a introdução das pinças e um para a câmara. A simulação torna-se mais prática uma vez que o simulador assegura que todos os circuitos de treino são montados numa única peça. A mala escolhida permite ainda que os recursos de treino estejam guardados, prevenindo danos ou perdas. Na base da mala podem ainda ser realizados treinos em órgãos animais, pois esta é facilmente lavável. As bases de treino estão colocadas sob um circuito elétrico onde qualquer erro cometido pelos profissionais, ou falha nas regras do nível, faz acender uma luz e posteriormente provoca o acionamento de um aviso sonoro. A base de treino é em cobre para garantir condutividade elétrica. Este sistema é baseado no sistema do Busca-Pólos, onde um pólo está ligado à pinça e outro pólo à placa de cobre e que, quando em contacto, acionam o sistema eléctrico.
- Electronic solution with joysticks for laparoscopic equipmentPublication . Costa, A. Carlos; Filho, César Ramos; Rocha, Joãolaparoscopic instruments. Many attempts of new models for handles of these equipment’s have already been proposed in an effort to combat this ergonomic problem in this type of instrument. The developed work aimed to develop an electronic solution for laparoscopic instruments in order to provide greater comfort to surgeons in the area. As a complement, a handle was manufactured to illustrate the system after downscaling for the surgeon to handle. Also, as a complement, a manual laser measuring plate was developed for future tests with the system attached to the handle. During the elaboration of the work was involved in the process the use of an Arduino Uno board among other electronic components, besides the design of parts in software, the use of 3d printing and laser cutting. The results obtained after the assembly of the electronic mechanism showed that it is possible to obtain the necessary movements for a surgical tool through an electronic drive, avoiding musculoskeletal injuries in surgeons who handle this equipment due to less repetitive efforts during operations.
- Control dos movimentos do servomotor usando o sinal EMGPublication . Krzyżanowska, Katarzyna; Duczmalewska, Aneta; Rocha, JoãoO objetivo do projeto era mover um servomotor com certo ângulo usando o sen- sor Bitalino EMG. Para esse fim, foi necessário desenvolver compatibilidade entre o sensor Bitalino EMG e a placa Arduino UNO. Além disso, o sinal bruto obtido a partir do sensor teve que ser transformado em sua forma apropriada para habilitar o controlo do servomotor. Vários conceitos e abordagens levaram a uma solução específica que con- tribuiu para o movimento do servomotor enquanto a contração muscular era detectada e ajustando o servomotor na posição inicial enquanto o músculo estava em repouso. Neste caso, com o uso de três eletrodos secos, investigou-se o músculo extensor digito- rum communis, cuja principal função é movimentar as falanges e o pulso. À medida que a eletromiografia permitiu as traduções de sinais bioelétricos em valores numéricos, a forma bruta do sinal foi deslocada e a função função módulo foi aplicada para obter apenas valores positivos. Posteriormente, o algoritmo foi usado para transformar o si- nal em forma envolvida. Tendo em conta os valores do sinal envolvido, o servomotor foi movido de acordo com a magnitude do limiar estimado. O valor limite corresponde à borda do sinal acima do qual a contração ocorreu, enquanto abaixo desse valor não foi denotada contração. O projeto serve de base para possíveis desenvolvimentos em diferentes áreas,, por exemplo, na criação de braço robótico ou prótese móvel para pessoas com deficiência. Assim, investigação mais ampla deve ser realizada a fim de proporcionar uma melhor fluência e menor tempo de reação entre a contração e os movimentos do servomotor.
- Detection of authorized genetically modified maize events: participation in an inter-laboratorial study.Publication . Rocha, João; Mafra, Isabel; Carvalho, Márcia; Amaral, Joana S.; Oliveira, BeatrizThe soybean and maize are the most important genetically modified (GM) crops (57% and 25% of global biotechnological planted area, respectively). The need to monitor and verify the presence of biotechnology-derived material in food products demands analytical methods able to detect, to identify and to quantify either the introduced DNA or the expressed protein(s). The interest of USDA/GIPSA Profiency program is to perform accurate, reliable, and reproducible testing on biotechnology-derived events.
- Moldações cerâmicas compósitasPublication . Rocha, JoãoO fabrico rápido de ferramentas, sem necessidade de maquinagem das faces de trabalho pode ser feito utilizando moIdações cerâmicas. Este processo utilizado na produção de peças de pequenas dimensões (de 50x50x25 mm até 250x250x250 mm) é mais económico que os processos convencionais de arranque de apara. Verifica-se, no entanto, que o fabrico de peças de grandes dimensões (maiores que 250x250x250 mm) tem um custo elevado. Neste trabalho, desenvolveu-se uma técnica e uma metodologia, tendo em vista o fabrico de moldações cerâmicas compósitas de grandes dimensões, superiores a 250x250x250, destinadas à produção rápida de ferramentas a baixos custos quando comparados com o processo tradicional. As propriedades destas moldações foram testadas por forma a reflectir as condições mais adequadas para resistir ao efeito do vazamento do metal liquido. Por forma a validar o processo, procedeu-se ao vazamento de 2 ferramentas metálicas em liga cobre-berílio. The fast production of tools, without the use of any machining on the work faces can be made through shaw casting. This process used in the production of parts of small dimensions (from 50x50x25 mm to 250x250x250 mm) is more economic than the conventional machining processes. It is verified, however, that the production of parts of great dimensions (bigger that 250x250x250 mm) has a high cost. In this piece of work, a technique and a methodology were specifically developed for the production of shaw casting composite of great dimensions, bigger than 250x250x250, destined to the fast production of tools, with a lower cost than the traditional process. The properties of the casting were tested in order to demonstrate the most adequate conditions to resist the effect of the pouring of the liquid metal. In order to validate the process, the pouring of 2 metallic tools in copper-beryllium alloy was executed.