IPS - ESTS – DEM - Artigos científicos
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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 do processo de gestão de projetos: um estudo de caso no setor da metalomecânicaPublication . Condeixa, Rui; Costa, Olga
- 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.
- 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.
- Applying design of experiments to a compression refrigeration cycle.Publication . Costa, Ricardo; Garcia, João
- Avaliação do risco de incêndio: Aplicação no núcleo antigo da vila da MoitaPublication . Gomes, Hugo; Costa, Olga
- Broader terms curriculum mapping: using natural language processing and visual-supported communication to create representative program planning experiencesPublication . Duarte, Rogério; Nobre, A.; Pimentel, Fernando; Jacquinet, MarcAccreditation bodies call for curriculum development processes that are open to all stakeholders, reflecting viewpoints of students, industry, university faculty, and society. However, communication difficulties between faculty and non-faculty groups leave an immense collaboration potential unexplored. Using the classification of learning objectives, natural language processing, and data visualization, this paper presents a quantitative method that delivers program plan representations that are universal, self-explanatory, and empowering; promoting stronger links between program courses and curriculum development open to all stakeholders. A simple example shows how the method contributes to representative program planning experiences and a case study is used to confirm the method’s accuracy and utility.
- A case study for decentralized heat storage solutions in the agroindustry sector using phase change materialsPublication . Simão, Carlos; Murta-Pina, João; Oliveira, João Pedro; Coelho, Luis Manuel Rodrigues; Pássaro, João; Ferreira, Diogo; Reboredo, Fernando; Jorge, Tiago; Figueiredo, PedroThe development of thermal energy storage solutions (TES) in agroindustry allows reduc- tion of production costs and improvement of operation sustainability. Such solutions require high storage capacity and the ability to adapt to existing equipment. The use of phase change materials (PCMs), which are able to store thermal energy as latent heat, creates new opportunities for heat storage solutions (LHS, latent heat storage) with higher energy density and improved performance when compared to sensible heat storage. New architectures are envisaged where heat storage is distributed throughout the production chain, creating prospects for the integration of renewable generation and recovery of industrial heat waste. This work aims to investigate the benefits of decentralized thermal storage architecture, directly incorporating PCM into the existing equipment of an agroindustry production line. To assess the feasibility and potential gain in the adoption of this TES/LHS distributed solution, a tempering and mixing equipment for food granules is selected as a case study, representing a larger cluster operating under the operation paradigm of water jacket heating. The behavior of the equipment, incorporating an inorganic PCM, is modeled and analyzed in the ANSYS Fluent software. Subsequently, a prototype is instrumented and used in laboratory tests, allowing for data collection and validation of the simulation model. This case study presents a demonstration of the increase in storage capacity and the extension of the discharge process when compared to a conventional solution that uses water for sensible heat storage.
- Classroom ventilation with manual opening of windows: Findings from a two-year-long experimental study of a Portuguese secondary schoolPublication . Duarte, Rogério; Gomes, Maria da Glória; Rodrigues, António Moret