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- An algorithm for fatigue crack growth applied to mixed and biaxial mode loadingsPublication . Baptista, Ricardo; Infante, V.; Freitas, M.Fatigue is still one of the main concerns when dealing with mechanical components failure. While it is fundamental to experimentally determine the fatigue material behavior using standard specimens, testing large and complex component geometries can be complicated. In these cases, the Finite Element Method can be a cost-effective solution but developing fatigue crack growth models is still a complicated task. In order to solve this problem, an algorithm for automatic crack propagation was developed. Using three different modules, the algorithm can generate a complex Finite Element Method model including a fatigue crack; solve this model considering complex loading conditions, by applying the superposition method; and calculate the fatigue crack propagation rate, using it to update the original model. In order to benchmark this solution two different problems were analyzed, a modified compact tension specimen and a cruciform specimen. By modifying the compact tension specimen hole location and simulating an initial crack, it was possible to understand how mixed mode conditions influence the fatigue crack path. Different load ratios and initial crack directions on the cruciform specimen were analyzed. Increasing the load ratio will increase the crack deflecting angle. The obtain solutions were compared with experimental results, showing good agreement. Therefore the developed algorithm can be used to predict the fatigue crack growth behavior on complex geometries and when different types of loads are applied to the component.
- Análise da secção E. (Produção e Consumo Alimentar)Publication . Soares, Aldina; Neto, Belmira; Farinha, Carla; Avelar, David; Alves, Elsa; Santos, Joana
- Análise das respostas obtidas ao inquérito, sobre sustentabilidade no ensino superior em Portugal, promovido pela rede campus sustentável, com foco na sustentabilidade da produção e do consumo alimentarPublication . Soares, Aldina; Neto, Belmira; Farinha, Carla; Avelar, David; Alves, Elsa; Santos, Joana
- Análise do processo de gestão de projetos: um estudo de caso no setor da metalomecânicaPublication . Condeixa, Rui; Costa, Olga
- Análise ergonómica de um posto de trabalho na indústria automóvel: reworkPublication . Amaro, Maria Délia; Costa, Olga
- Análise experimental do desempenho de envidraçados com películas de controlo solarPublication . Pereira, Júlia; Gomes, Maria da Glória; Rodrigues, António Moret; Duarte, RogérioA utilização do vidro na construção tem tido uma expressão cada vez mais significativa, resultando em rácios de envidraçado na fachada muito elevados, especialmente em edifícios não residenciais. Esta tendência deve-se às boas características estéticas e óticas do vidro que permitem a entrada de luz natural e visão para o exterior, podendo contribuir para poupanças de energia com iluminação e conforto visual. No entanto, os ganhos solares pelos envidraçados, especialmente em climas com verões quentes e prolongados, contribuem de forma muito significativa para as cargas térmicas de arrefecimento e podem originar problemas de encadeamento, perturbando a produtividade dos utilizadores. A película de controlo solar, desenvolvida para aplicação em envidraçados na indústria da construção civil, tem como objetivo principal reduzir as cargas térmicas de um espaço interior, impedindo a passagem de radiação em todo o espectro de radiação solar ou em certos comprimentos de onda específicos. Com o objetivo de avaliar a eficiência térmica e lumínica de películas de controlo solar, foi realizada uma campanha experimental no período de verão e no período de inverno em dois gabinetes semelhantes localizados em Lisboa. Um deles, considerado como gabinete de referência, não tem película aplicada no envidraçado e o outro tem aplicada uma película no envidraçado. Os resultados observados mostram que a película melhora o desempenho térmico e lumínico do ambiente interior durante o período de verão no gabinete em que está aplicada, o qual registou uma diminuição dos valores de temperatura interior comparativamente ao gabinete de referência, o que pode conduzir a uma diminuição do consumo de energia com arrefecimento. Durante o período de inverno, o gabinete com película de controlo solar apresentou valores de temperatura e de iluminação natural inferiores aos valores observados no gabinete de referência, diminuindo as condições de conforto no ambiente interior.
- Analysis of Pedestrian Short-Term Exposure on a High Traffic City StreetPublication . Garcia, João; Cerdeira, Rita; Tavares, Nelson; Coelho, Luis Manuel Rodrigues; Carvalho, M. G.
- Analysis of temporal lag in the impact of air quality on the health of children, in BarreiroPublication . Garcia, João; Cerdeira, Rita; Coelho, Luis Manuel RodriguesThe aim of this work was to study the impact of temporal lag between the exposition to air pollutants and the children admitted to the emergency room of Hospital Na Sra Rosário pediatric service, in Barreiro, Portugal, with symptoms of respiratory problems. The two variables were recorded by the medical staff and by an air quality monitoring station, in the same periods. From the results, a moderate correlation between different symptoms of respiratory diseases (sdr, cough, and asthma) and pollutants was found, reaching maximum values after temporal lags of 2 to 6 days. The strongest correlation for lag 0 (consequences on the same day) rises for the symptomatology of asthma, reaching the highest values for COmax (ρ = 0.26) and COpeak (ρ = 0.25). Also, an important correlation was found for NOx, NOx med and peak NOx (ρ = 0, 21). The correlation with PM10 shows an unrepresentative value (ρ = 0.09), being negative for O3max (ρ = 0.23) and O3peak (ρ = 0.22), as well as for SO2med (ρ = 0.12). Considering temporal lags of 1 to 8 and 15 days, overall, the maximum correlations between symptoms and NO, NO2, NOx, CO, and PM10 occur after temporal lags of 2 to 6 days, being constant or negative to SO2 and O3.
- Aplicação do Desenho de Experiências a um Ciclo de RefrigeraçãoPublication . Costa, Nuno; Garcia, João
- Applying computational fluid dynamics in the development of smart ripening rooms for traditional cheesesPublication . Alvarenga, Nuno; Martins, João; Caeiro, José; Garcia, João; Passáro, João; Coelho, Luis Manuel Rodrigues; Santos, Maria Teresa; Lampreia, Célia; Martins, António; Dias, JoãoTraditional ewe’s cheese producers face certain challenges caused by fluctuating envi- ronmental parameters inside the ripening room, which lead to lack of homogeneity in the final product. The present research discusses the application of computer fluid dynamics for simulating the distribution of environmental parameters, predicting the airflow pattern, and identifying critical areas where such parameters could cause reduced cheese quality. A new monitoring system was developed including presence sensors, temperature and humidity dataloggers, pneumatic actua- tors, microcontrollers, and microcomputers connected remotely for control, data visualization, and processing. The validation of the computer simulation and monitoring system was made with a batch of 40 ewe’s cheeses distributed in three different zones inside a prototype ripening room and ripened for 35 days. At 35 days, a physical, chemical, and microbiological characterization of cheeses was made for evaluation of the influence of environmental conditions on cheese quality. The comparison between simulated and local measurements showed close agreement, especially concerning air velocity inside the stacks of cheese. The results of Pearson’s correlation analysis and PCA concluded that temperature affected the appearance of the rind, hardness, number and area occupied by holes. Humidity affected aw and mFeret. Air velocity affected pH and the circularity of gas holes.