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- Comparação da solucão numérica de equações constitutivas para ligas com memória der formaPublication . Hilário, Jean César; Andrade, Carlos A.R.; Braz-César, Manuel; Borges, AdailtonA utilização de materiais inteligentes vêm se tornando essencial para o aperfeiçoamento de aplicações existentes e o desenvolvimento de novas tecnologias. As ligas com memória de forma fazem parte desta classe de materiais, onde as suas características ímpares possibilitam a aplicação como por exemplo: amortecedores, sensores e atuadores. Tendo como objetivo a aplicação destas ligas, será necessário a possibilidade de simular fielmente o comportamento destas, de forma a diminuir custos relacionados com produção de protótipos e o respectivo tempo necessário para produzi-los. O presente trabalho vem comparar as soluções apresentada por dois modelos constitutivos para a mesma liga de Níquel-Titânio, utilizando um algoritmo implementado em Matlab® e o software comercial Ansys® Workbench™. Os resultados apresentam as diferenças quantitativas nos modelos e a respectiva análise mostra os fenômenos que foram levados em conta durante a simulação. Pelo que são necessários ensaios experimentais para a validação dos fenômenos mencionados, calibração dos modelos e comparação para assim identificar o modelo mais representativo na representação do comportamento real da liga.
- Evaluation of cost-optimal retrofit investment in buildings: the case of Bragança fire station, PortugalPublication . Cova, Sónia; Andrade, Carlos A.R.; Soares, Orlando; Lopes, JorgeOffice buildings built before the entry into force of the first thermal regulation in 1991 constitute a relevant group for analysing the energy performance of the Portuguese building sector. A dynamic energy simulation was used to assess the energy performance of an existing office building located in the town of Bragança, Portugal. Four energy efficiency measures were selected and a financial evaluation through the internal rate of return (IRR) method was undertaken to choose the best retrofit option for improving the building’s energy performance. An investment package consisting of the roof insulation and a new equipment for the domestic hot water system presented an IRR higher than the discount rate used in the analysis, and, thus, a positive financial return. The results of the study also suggest that the EU’s comparative methodology framework is not particularly suitable for assessing building retrofit investment at the private investor’s perspective and further refinement in the cost-effective approach to renovations is needed to help stimulate building’s energy renovation market. Suggestions for further studies conducted for office buildings in the different climate zones in Portugal are also proposed.
- Experimental methods in building acoustics for evaluating the flanking transmissionPublication . Andrade, Carlos A.R.All the scientific work must have at the beginning presupposes and assumptions clarified, that could lead to an objective more easily to accomplish. In this line of thought, the present work is to achieve and clarify those presupposes and assumptions. The design of building and his constructions techniques must be built in such a way that the noise perceived by the occupants is kept down to a level that will not threaten their health and satisfactory living conditions. The acoustical comfort is nowadays one of the main issues for the satisfaction and integration on the society. This has more relevance in developed countries. There are many places where the normal human living is developed: home, work, leaser places, etc, has there are many forms of sound power that disturb those places. However, where the sound perturbation must not reach intolerable levels (acoustical comfort) are in buildings, especially in living buildings. Nowadays is known that sound could be transmitted by structural vibration or by other paths than the separating element of the dwellings. These paths could increase the sound levels of the adjoining rooms with a bigger importance than the supposed a few years ago. The present and future works are more a contribution to obtain better acoustical conditions in buildings and put to the scientific community more knowledge and “savoir faire”. Firstly a search was made in reviews, books and papers specialized in the areas of knowledge of building acoustics and flanking transmission. The information recovered was treated to clarify all the present work done till the moment and to put us in the center of the issue. Secondly several measurements were performed in an old building of the university (in situ measures), by pressure method and intensity method. Those measures were then treated, processed, compared and finally discussed to accomplish the main objective of this work, which is getting an objective theme to the future doctoral thesis.
- Desempenho energético do edifício dos Bombeiros Voluntários de BragançaPublication . Cova, Sónia; Andrade, Carlos A.R.; Soares, OrlandoAtualmente o consumo energético dos edifícios é um tema de elevada importância, pois estes são os principais responsáveis pelo consumo de energia global, logo pelo aumento da poluição, emissão de gases e aquecimento global. Consequentemente as fontes de energia fósseis escasseiam rapidamente, e o seu período de renovação é lento, não conseguindo acompanhar o aumento da procura para suprir as necessidades energéticas. Torna-se fundamental tomar medidas para reduzir o impacto do consumo global de energia, incitando a uma utilização racional da energia, promovendo a eficiência energética e o desenvolvimento sustentável. Este artigo pretende demonstrar uma metodologia para avaliar o desempenho energético do edifício dos Bombeiros Voluntários de Bragança através da simulação dinâmica multizona, com recurso a um programa acreditado pela Norma ASHRAE 140-2004, que no caso em estudo foi o DesignBuilder'" que usa como motor de cálculo o EnergyPlus®. Para a modelação do edifício foi necessário realizar um levantamento de todas as soluções construtivas, das cargas elétricas e térmicas, assim como dos perfis de utilização/atividade em todas as zonas do edifício, para fazer uma caraterização exaustiva e aproximada da realidade do edifício. Com os resultados obtidos foi possível efetuar a avaliação do desempenho energético do edifício, verificando que existe um grande desperdício de energia devido às perdas pela envolvente e à baixa eficiência dos sistemas de produção de AQS. Além disso, são avaliadas as implementações de medidas de melhoria que visam, por um lado, melhorar as condições e conforto dos utilizadores e, por outro, a redução dos consumos da energia do edifício.
- Determination of the drag coefficient of an autonomous solar lighting column using wind tunnel simulation and computational analysisPublication . Dias, Vitor Hugo da Silva; Andrade, Carlos A.R.; Andrade, Carlos A.R.; Roque, João; Rosa, Sérgio; Gomes, Francisco Augusto AparecidoPhotovoltaic solar panels have many applications and among them are the autonomous solar lighting columns, which has been growing in popularity in urban and rural enviroments. These columns are installed in open regions and have their structure exposed to the mechanical actions imposed by the wind, so they need to be correctly designed to support them. There are aerodynamic variables that must be determined for the design of these columns, especially the drag coefficient, a property linked to the geometry of a body, which represents its interaction with a flowing fluid. Due to the complexity of determining these variables, experimental methods are constantly used to obtain these values. Classically, wind tunnel simulations are used for this purpose, but they can be expensive and difficult to perform, so that fluid computational analysis has been widely applied to replace physical analysis. In this work, the drag coefficient of an autonomous solar illumination column is determined by wind tunnel simulations and computational analysis using various body positions in relation to the direction of flow. The drag coefficient determined using wind tunnel simulations varies between 0.65 and 0.80 while for computational methods it varies between 0.43 and 0.73. With the obtained results it is possible to perform a verification of the fidelity of the data obtained by computational means when compared to those obtained through the wind tunnel simulations obtaining an average error of 9.2% and 27.2% for the computational methods used.
- Estudio vibro-acústico y intensimétrico de las transmissiones por flancos en edifícios.Publication . Andrade, Carlos A.R.El esfuerzo que se ha realizado al estudiar las prestaciones acústicas de algunas soluciones constructivas sencillas propias del sur de Europa, haciendo especial hincapié en el efecto de las transmisiones indirectas.
- Determination of the drag coefficient of an autonomous solar lighting column using wind tunnel simulation and computational analysisPublication . Dias, Vitor Hugo da Silva; Andrade, Carlos A.R.; Rosa, Sergio; Roque, João; Francisco, GomesThe Sun is the largest source of energy available and many studies for the development of technologies capable of harnessing this energy are constantly being conducted. Among the technologies developed are photovoltaic solar panels that have many applications and among them are the autonomous solar lighting columns that have been growing in popularity especially in urban and industrial environments. These columns are installed in open regions and have their structure exposed to the mechanical actions imposed by the wind, so they need to be correctly designed to support them. There are aerodynamic variables that must be determined for the design of these columns, especially the drag coefficient, a property linked to the geometry of a body, which represents its interaction with a flowing fluid. Due to the complexity of determining these variables, experimental methods are constantly used to obtain these values. Classically, wind tunnel simulations are used for this purpose, but they can be expensive and difficult to perform. Fluid dynamic computational analysis has been widely applied to replace physical analysis. In this work, the drag coefficient of an autonomous solar lighting column is determined by wind tunnel simulations and computational analysis. With the obtained results, a comparison is made to verify the fidelity of the data obtained by computational means when compared to those obtained through the wind tunnel simulations.
- Estudo numérico e experimental de uma liga com memória de formaPublication . Hilário, Jean César; Andrade, Carlos A.R.; Braz-César, Manuel; Borges, AntónioO trabalho desenvolvido no âmbito do Instituto Politécnico de Bragança engloba a caracterização do comportamento superelástico de uma liga com memória de forma (LMF) tendo maioritariamente em sua composição Níquel e Titânio. Através de estudos experimentais e calibração de modelos numéricos pretendemos simular o comportamento ímpar das ligas, com o intuito de possibilitar o desenvolvimento de dispositivos capazes de atenuar vibrações indesejadas de altas amplitudes, como em fenômenos de flutter ou sismos.
- Matlab® algorithm to simulate the dynamic behavior of an NiTi alloy through Ansys® APDL modelsPublication . Hilário, Jean César; Braz-César, Manuel; Andrade, Carlos A.R.; Borges, AdailtonIn recent years, technological advances related with the so-called intelligent materials have been exploited for problem solving in many engineering fields. In this regard, shape memory alloys (SMA) seem suitable for medical and engineering applications and many others. These alloys have the ability to return the original form after an apparently plastic deformation by applying heat and the also ability to perform phase changes with voltage variations under a specific temperature. These properties allow the development of a hysteretic loop with energy dissipation, which can be used as a damping element in a vibratory system. In this paper, a MATLAB® algorithm was developed to create an interface with the Ansys® APDL™ software that simulate the dynamic behavior of a SMA. The software is capable to obtain the cyclical behavior of a vibratory mechanical system based on the energy dissipation properties of the SMA. The results shown that the free vibration of a mass-damper (alloy) system presents the energy dissipation related in magnitude with the area of the hysteresis loop until the deformation caused by the motion which does not correspond to a voltage required to initiate the (direct) phase transformation of the material, thus reducing the displacement to a constant level.
- Analysis of heat balance in a light steel frame residence with different insulating thicknessPublication . Consoli, Isabel Oberderfer; Andrade, Carlos A.R.; Tabalipa, Ney LyzandroSustainability and efficiency in buildings are concepts that have been recently growing and developing. Its application in several buildings has become mandatory in many countries around the world. One of the major challenges faced by sustainable buildings is the achievement of satisfactory levels in efficiency terms, without negatively impacting the economics. The residential construction sector has great potential for energy savings and is also where building strategies need to be carefully planned, as they seek to meet the needs of residents not only in the present, but also over time. Residential design must be done thoroughly and must include the analysis of all climate variables involved. In order to verify a residential building envelope behaviour regarding energy and thermal efficiency, this paper intended to evaluate through software Design Builder®, walls and roofs with a rock wool layer, placed in a Light Steel Frame (LSF) house.
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