ISEL - Instituto Superior de Engenharia de Lisboa
URI permanente desta comunidade:
Navegar
Percorrer ISEL - Instituto Superior de Engenharia de Lisboa por Domínios Científicos e Tecnológicos (FOS) "Engenharia e Tecnologia::Engenharia Mecânica"
A mostrar 1 - 10 de 66
Resultados por página
Opções de ordenação
- Análise das condições de deposição na produção de componentes híbridos por impressão 3DPublication . Paiva, Marcelo Kendrick de; Galvão, Ivan Rodolfo Pereira Garcia de; Almeida, Pedro Lúcio Maia Marques de; Leitão, Carlos Miguel AlmeidaO desenvolvimento de juntas híbridas entre metais e polímeros tem ganhado destaque em aplicações estruturais leves, especialmente nas indústrias automotiva e aeroespacial. Esse tema é de grande importância, pois, com o surgimento de novas técnicas de ligação entre materiais, como soldadura por fricção e união mecânica, a união híbrida de materiais distintos possibilita a criação de novos materiais que combinam as características e qualidades de cada um, resultando em componentes cada vez mais leves, resistentes e confiáveis. O objetivo deste trabalho destinou-se a analisar as condições de deposição na produção de componentes híbridos (metal-polímero) por modelação por deposição fundida (FDM). Em particular, foi estudada a ligação de chapa de alumínio (Al) a Ácido Polilático (PLA) impresso. Por forma a estudar as condições de adesão na interface metal-polímero, foram testadas diferentes condições topográficas dos componentes de Al. Sobre estas superfícies foram depositadas, por prensagem a quente, películas poliméricas, que funcionarão como camadas intermédias facilitadoras da deposição de material polimérico por FDM, para se avaliar e comparar a resistência da adesão entre os materiais sob essas diferentes preparações superficiais. Foram produzidas amostras em três condições distintas, sem preparação, com lixamento, e com texturização superficial. A caracterização morfológica foi realizada por microscopia óptica e microscopia digital, se analisando as condições de deposição do material polimérico na topografia da placa de Al. Os resultados mostraram que a texturização superficial melhorou as condições de adesão da junta, em comparação com as demais condições de preparação do substrato do Al, sugerindo uma melhor ancoragem mecânica da junta. A preparação da superfície do Al demostrou ser um fator crucial para a eficiência da junta híbrida Al/PLA, revelando a importância de se realizar um controlo topográfico neste tipo de aplicação para o fabrico aditivo pelo método de FDM.
- Análise técnico-económica de soluções energéticas alternativas ao aquecimento por vapor na indústria alimentarPublication . Inverno, Inês Filipa Fernandes; Casaca, Cláudia Sofia Séneca da Luz; Teixeira, Ana Cristina PereiraA crescente preocupação com o impacto das emissões de gases com efeito estufa na intensificação do aquecimento global tem conduzido à procura de medidas que promovam a transição energética e a neutralidade carbónica. A definição de metas internacionais e nacionais para a redução das emissões obriga à reavaliação de processos industriais dependentes de combustíveis fósseis, nomeadamente os associados ao aquecimento a alta temperatura. No âmbito do estágio de natureza profissional, em colaboração com a ACET – Antero Cardoso Engenharia Termodinâmica, Lda., procedeu-se à análise técnico-económica de soluções energéticas alternativas ao aquecimento por vapor num complexo industrial de produção de margarina. O processo em estudo apresenta elevada exigência térmica, atualmente suprida por vapor gerado numa caldeira a gás natural. Foram estudadas três soluções: (i) bomba de calor amoníaco-água (R717-H2O), (ii) configuração em cascata com bomba de calor ar-água e bomba de calor água-água (ar-H2O-H2O) e (iii) caldeira elétrica de resistência. A comparação considerou consumo energético, viabilidade tecnológica e impacto económico. A bomba de calor amoníaco-água é a alternativa mais viável. Relativamente à bomba de calor ar-H2O-H2O e à caldeira elétrica de resistência, apresenta coeficiente de desempenho 2,1 e 4 vezes superior e custo total (incluindo o investimento inicial) 2,4 e 4,3 vezes inferior, traduzindo-se em poupanças estimadas de 4 931 712 € e 11 425 247 €, respetivamente. Além das vantagens energéticas e económicas, esta solução reduz o desperdício térmico e o consumo elétrico do sistema de refrigeração existente, permitindo integração térmica entre aquecimento e arrefecimento. Esta abordagem contribui para a sustentabilidade energética e para a redução da pegada carbónica da instalação industrial.
- Analysis of reinforced cork composite sandwich beamsPublication . Costa, Sérgio Filipe Marques Campos; Leite, Afonso Manuel da Costa de Sousa; Santos, Hugo Alexandre Freixial Argente dosAbstract Considering the continuous increase in the use of lightweight, biological, and renewable materials across all industries, cork—being a material that meets all these requirements while also offering exceptional mechanical characteristics such as high resistance to compression as well as to tension—generates significant interest for testing and studying its behavior in engineering applications. Thus, this study aims to carry out an experimental and numerical investigation of composite sandwich beams using cork agglomerate as the core, compare the results with previous studies and with other materials widely used today, and discuss their feasibility and limitations in potential applications. Several specimens were used, distributed into three types: T1, T2, and T3. The specimens are made of laminated composite, using epoxy resin and glass fiber fabric for the skins, and a cork agglomerate core. The different beam types also present different configurations of skin and core thicknesses and include fiber layers in the core region as well. Three-point bending tests were performed according to ASTM C393 to study their mechanical behavior, calculate their flexural stiffness, shear strength, and other relevant properties such as bending stress in the skins, critical shear stress of the core, and the shear stiffness of the sandwich structure. A numerical study based on finite element analysis of a 2D model developed in Ansys software was conducted to simulate the behavior of the specimens in the linear elastic regime and to verify the experimental results. The numerical results deviate from the experimental ones with respect to the deformed shape; however, there is a reasonable correlation in terms of the force–displacement curve in the linear elastic regime.
- Analysis on the effectiveness of the weldability window in predicting results for explosive weldingPublication . Peladinho, Duarte Miguel Gonçalves; Galvão, Ivan Rodolfo Pereira Garcia de; Carvalho, Gustavo Henrique Senna de Freitas Ligeiro de; Leal, Rui Manuel FerreiraAbstract Explosive welding (EXW) is a solid-state joining process that relies on controlled detonation to achieve metallurgical bonding between similar or dissimilar materials. Its advantages include the ability to combine metals with large differences in melting point and thermal conductivity, the near absence of a heat-affected zone, and the potential for producing large-scale joints. Nevertheless, the main limitation of EXW remains the lack of a reliable theoretical framework capable of predicting weld quality. To address this limitation, the weldability window was introduced as a graphical tool relating collision velocity and collision angle to the likelihood of a successful weld. Although widely used, this model often fails to reproduce experimental results, mainly due to the diversity of proposed equations, the boundary conditions considered during their development, and the incomplete understanding of interfacial mechanisms such as wave formation and jetting. The objective of this work is to analyse the effectiveness of the weldability window in predicting the outcomes of explosive welding by reviewing and comparing the most relevant theoretical formulations with experimental results available in the literature. The examination of these approaches highlights the assumptions behind each model and reveals important divergences regarding their applicability to different materials and welding conditions. The analysis shows that current formulations contain inconsistencies that restrict their predictive capability, resulting in discrepancies between theoretical boundaries and actual weld behaviour. These limitations emphasize the need for further refinement of the weldability window in order to provide a more accurate and reliable framework for assessing the occurrence of successful welds in explosive welding processes.
- Ardosia: simulating circuits and robotic systems in a platformPublication . Marnoto de Oliveira Campos, Francisco MateusCircuit simulation, together with practical sessions, is considered a fundamental tool to assist in the teaching of electronics. Robotics offers rich real-world applications that foster student interest in developing engineering projects. Despite the potential benefits of uniting these two realities, software tools that combine circuits and robotic systems in a single simulation platform are scarce. This article presents Ardosia, a simulation software that combines electronics and robotics in a single simulation arena. The electronic aspects of the simulation are handled by the Falstad Circuit Simulator, a software with proven success in promoting student interest and learning outcomes. Importantly, this software features significant interactive and visualization characteristics that are deemed valuable to enhance conceptual understanding. Non-electrical physics simulation is performed by a special-purpose engine, designed to simulate sensor and actuator behavior in a 2-D world. In combination, the two simulation engines yield a model where electronic circuits are embodied in the world through robot sensors and actuators interacting together and with the surroundings. Such a simulator is intended to promote the use of robotics projects in electronics education, since students will be equipped with software to conveniently design and evaluate robotic systems, through simulation, before applying their ideas in an experimental setting. This article presents an overview of Ardosia, complemented with examples of use in electronics education and a validation experiment comparing simulation with real-world data.
- Assessing the contribution of ERASMUS+ KA2 projects to the SDGs: an exploratory analysisPublication . Nogueira, João Robert; Dantas, Lucimar; Galego, Carla; Marques, PedroThis study examines the contribution of ERASMUS+ Key Action 2 (KA2) projects, funded between 2014 and 2020, to the dissemination and promotion of the United Nations Sustainable Development Goals (SDGs). A predominantly quantitative content analysis was conducted based on metadata extracted from the official European Commission database, focusing on the presence of SDG-related keywords within the titles, topics, and abstracts of the projects. In total, 24,838 KA2 projects were examined. The findings reveal a growing alignment between funded projects and certain SDGs, particularly SDG 3 (Good Health and Well-being), SDG 4 (Quality Education), SDG 13 (Climate Action), SDG 7 (Affordable and Clean Energy), and SDG 9 (Industry, Innovation, and Infrastructure). In contrast, goals such as SDG 2 (Zero Hunger), SDG 6 (Clean Water and Sanitation), and SDG 14 (Life Below Water) are scarcely represented. Overall, the results demonstrate an increasing commitment to sustainability themes over time and also highlight notable gaps in the promotion of several SDGs. This analysis offers valuable insights into the strategic alignment of ERASMUS+ funding with the 2030 Agenda and identifies opportunities for strengthening its future contributions to sustainable development.
- Assessment of decarbonization scenarios for the portuguese road sectorPublication . Salvador, João; Duarte, Gonçalo; Baptista, Patrícia C.Abstract This study presents a scenario-based modeling framework to evaluate potential decarbonization pathways for Portugal’s road transport sector. The model simulates the evolution of a light-duty vehicle (LDV) fleet under varying degrees of electrification and biofuel integration, accounting for energy consumption, CO2 emissions and market shares of alternative propulsion technologies. Coupled with projected energy mix trajectories, the framework estimates final energy demand and well-to-wheel (WTW) emissions for each scenario, benchmarking outcomes against national and European climate targets. A key structural limitation identified is the long vehicle survival rate—averaging 14 years—which constrains fleet renewal and delays the transition to full electrification. Diesel-powered light commercial vehicles exhibit even slower replacement dynamics, rendering the Portuguese targets of full electrification by 2030 highly improbable without targeted scrappage and incentive programs. Scenario analysis indicates that even with accelerated electric vehicle (EV) uptake, battery electric vehicles (BEVs) would comprise only 12% of the fleet by 2030 and 77% by 2050. Electrification scenario raises electricity demand fortyfold by 2050, stressing generation and infrastructure. Scenarios that consider diversification of energy sources reduce this strain but require triple electricity for large-scale green hydrogen and synthetic fuel production.
- Assessment of influential operational parameters in the mitigation of CO2 emissions in a power plant: case study in PortugalPublication . Balanuta, Vítor; Baptista, Patricia; Neves da Fonseca Cardoso Carreira, Fernando Paulo; Duarte, Gonçalo; Casaca, Cláudia Sofia Séneca da LuzThe European decarbonization goals and requirement for energy independence are mostly relying on intermittent renewable energy sources for electrification. A numerical model was developed to simulate the operation of a steam generator, allowing a study of the potential impacts of retrofitting existing coal-fired power plants to operate with biomass or coal–biomass mixtures on combustion parameters and CO2 emissions. The results obtained using the operational parameters of the Sines power plant indicate that a mixture of 25% coal and 75% pine sawdust allow operation at λ = 1.8, demonstrating that a small amount of coal allows operation near the coal combustion parameters (λ = 1.9). These conditions have the drawback of a reduction of 8.7% in adiabatic flame temperature but a significant reduction of 57.5% in CO2 emissions, considering the biomass as carbon-neutral.
- Assessment of influential operational parameters in the mitigation of CO2, emissions in a power plant: case study in PortugalPublication . Balanuta, Vítor; Baptista, Patrícia; Carreira, Fernando; Duarte, Gonçalo O.; Casaca, Cláudia S. S. L.The European decarbonization goals and requirement for energy independence are mostly relying on intermittent renewable energy sources for electrification. A numerical model was developed to simulate the operation of a steam generator, allowing a study of the potential impacts of retrofitting existing coal-fired power plants to operate with biomass or coal–biomass mixtures on combustion parameters and CO2 emissions. The results obtained using the operational parameters of the Sines power plant indicate that a mixture of 25% coal and 75% pine sawdust allow operation at λ = 1.8, demonstrating that a small amount of coal allows operation near the coal combustion parameters (λ = 1.9). These conditions have the drawback of a reduction of 8.7% in adiabatic flame temperature but a significant reduction of 57.5% in CO2 emissions, considering the biomass as carbon-neutral.
- Characterization of the fracture forming limits by radial extrusionPublication . Sampaio, Rui F.V.; da Fonseca Matos Pragana, João Pedro; Bragança, Ivo; Silva, Carlos; Nielsen, Chris Valentin; Martins, Paulo