Mestrado em Engenharia Mecânica
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- ItemDesenvolvimento de atuadores flexíveis com elastômeros dielétricos constrito por fibras com sensores de fibra óptica integrados(Universidade Federal do Espírito Santo, 2025-10-09) Silva, Alexandre Bernardo Santos da; Andrade, Rafhael Milanezi de; https://orcid.org/0000-0002-2839-3649; http://lattes.cnpq.br/9241045307171389; https://orcid.org/0009-0006-3506-046X; http://lattes.cnpq.br/1319231972690339; Leal Júnior, Arnaldo Gomes; https://orcid.org/0000-0002-9075-0619; http://lattes.cnpq.br/7246557168481527 ; Vimieiro, Claysson Bruno Santos; https://orcid.org/0000-0003-1916-0517; http://lattes.cnpq.br/0149542794493944Advances in motor rehabilitation have driven the development of technologies capable of interacting with the human body. In this context, exible actuators emerge as a promising alternative to rigid actuators, as they more closely resemble the behavior of natural muscles, enabling their application in wearable robotic joints for rehabilitation. This work presents the development of ber-constrained dielectric elastomer actuators (FCDEAs). Initially, static tests were conducted to evaluate the inuence of parameters such as pre-stretch, dimensions, and mechanical load on displacement and deformation. Subsequently, an optical ber in a serpentine con guration was embedded within the FCDEA, correlating optical power loss with displacement measured through image tracking techniques. A total of 36 tests were performed under varying geometric and mechanical conditions, along with oscillatory tests at di erent excitation ranges (0˘5V ;100mHz) and frequency-domain analyses using chirp signals and Bode diagrams. The results indicate that the developed actuators are capable of achieving 90% deformation, and the optical ber proves e ective for displacement measurement at low frequencies, showing good correlation between optical power and deformation, particularly at higher excitation amplitudes. Despite the limitations observed in static tests and the reduced accuracy of 69% in the Bode diagram, the dynamic analysis demonstrated the feasibility of the proposed approach for future applications in actuators and closed-loop control sensing systems.
- ItemPrevisão da distribuição do tamanho de gotas em escoamento de emulsões por modelo de balanço populacional: simulação numérica e experimentos(Universidade Federal do Espírito Santo, 2025-03-20) Elias, Murilo Zucatelli; Ramos, Rogério; https://orcid.org/0000-0003-4493-2435; http://lattes.cnpq.br/2975022316691139; https://orcid.org/0009-0009-7422-2101; http://lattes.cnpq.br/6373443252232198; Lage, Paulo Laranjeira da Cunha; https://orcid.org/0000-0002-0396-5508; http://lattes.cnpq.br/5576851640501227; Siqueira, Renato do Nascimento; https://orcid.org/0000-0002-8397-8180; http://lattes.cnpq.br/9791817633014124During oil production, shear and turbulence in the Ćow progressively break water droplets, leading to the formation of stable water-in-oil (W/O) emulsions. This study investigated the droplet breakup and coalescence dynamics in W/O emulsions through laboratory experiments and population balance modeling. The research was conducted using the NEMOG/UFESĆowcircuit, focusing on the impact of gate valve restrictions on the droplet size distribution (DSD). The Coulaloglou and Tavlarides (CT) and Mitre et al.(CEM) published models were applied to simulate the observed phenomena, with parameter adjustments to optimize predictions against experimental data. Results showed that the MV-01 valve, located at the circuitŠs inlet, predominantly induced droplet breakup, causing a moderate reduction in the mean droplet size. In contrast, the downstream MV-02 valve exhibited greater variability in DSD due to a signiĄcant increase in coalescence events, particularly at dispersed phase concentrations exceeding 15% v/v. The implemented models effectively predicted the DSD for water volume fractions of 5%, 10%, and 15% v/v. The CEM model demonstrated superior overall performance, even with its original parameters, although it underestimated coalescence effects at high dispersed-phase concentrations. With mean errors ψ of approximately 40% for MV-01 and 16% for MV-02 when considering the distribution. Predictions of the mean droplet diameter, De brouckere, yielded mean errors ψ below 23% for MV-01 and 9% for MV-02. The CT model showed limitations in fully describing coalescence phenomena, requiring additional adjustments under severe conditions. Factors such as water volume fractions and the heterogeneous distribution of turbulent energy were identiĄed as critical for improving predictions. Sensitivity analysis revealed that breakup and collision parameters (Cb and Cc) had the most significant inĆuence on prediction errors, whereas the coalescence efficiency parameter (Ce) had a negligible impact. Experimental results partially corroborated model predictions, with average and maximum errors comparable to those reported in the literature. The maximum error in the predicted volume-weighted mean droplet diameter (D[4,3]) was 25.6%, highlighting the need for advancements in submodels for coalescence and energy dissipation to enhance simulation accuracy.
- ItemModelagem computacional da formação de torta de filtração em filtros de manga(Universidade Federal do Espírito Santo, 2024-10-25) Zanete, Hóliver Zambon; Rocha, Sandra Mara Santana ; https://orcid.org/0000-0001-8787-7849; http://lattes.cnpq.br/9653853675618723; Siqueira, Renato do Nascimento ; https://orcid.org/; https://orcid.org/0000-0002-8397-8180; http://lattes.cnpq.br/9791817633014124; https://orcid.org/0009-0007-9184-6210; http://lattes.cnpq.br/3841315513918026; Sartim, Rafael ; https://orcid.org/0000-0002-5678-2027; http://lattes.cnpq.br/0380809249444032; Fernandes, Leandro Marochio ; https://orcid.org/0000-0003-4965-7233; http://lattes.cnpq.br/5933630468428555The growing concern about the impacts of atmospheric pollution on the environment has driven the development of efficient technologies for controlling particulate emissions. Among these technologies, bag filters stand out as effective devices for removing particles from gas streams. These filters consist of a set of filter bags, usually made of fabric or felt, that retain solid particles while clean air passes through the filtering medium. As particles deposit on the surface of the filtering medium, they form a layer known as the filtration cake. This cake increases the resistance to airflow, leading to a higher pressure drop in the system. In this context, a detailed understanding of cake formation is essential for the design and optimization of bag filters. In this work, the implementation of a subroutine based on CFD (Computational Fluid Dynamics) was proposed to predict the formation of the filtration cake in bag filters. Darcy’s law was modified to incorporate particle deposition’s effects on the filter media’s surface on its permeability. The developed subroutine was validated against experimental data available in the literature and subsequently applied to a real bag filter. Three different superficial filtration velocities (5, 10, and 15 cm/s) were evaluated. Initially, the simulations were conducted under singlephase flow conditions (without particle injection), allowing for the fluid dynamics analysis at the beginning of the filtration process. Higher filtration velocities resulted in greater pressure drop. Additionally, the effect of the energy equation on the distribution of flow along the filter surface was observed. After the convergence of the single-phase simulations, particles with a diameter of 5,7 µm and a density of 2,79 g/cm3 were injected at a rate of 0,00127 kg/s for 250 seconds. The results indicated that the formation of the cake redistributed the airflow through the bags, promoting uniformity of the flow along the section of the filter element. It was found that the filling of the filtration chamber alters the pressure drop profile at the beginning of filtration and that, after the stabilization of the particle deposition rate, the increase in pressure drop begins to exhibit linear behavior. The identification of preferential zones for cake formation can significantly contribute to the optimization of bag filter designs
- ItemMetamodelagem para análise térmica no torneamento com ferramenta de aço rápido usando redes LSTM(Universidade Federal do Espírito Santo, 2024-12-13) Santos, Hugo dos Anjos; Dutra, Júlio Cesar Sampaio; Silva, Wellington Betencurte da; Macedo, Marcelo Camargo Severo de; Abreu, Luiz Alberto da SilvaThe prediction of temperature distribution during the turning process is essential for optimizing machining operations and extending tool life. This study investigates the application of LSTM neural networks to model the temperature field in turning operations using high-speed steel tools. The research compares numerical simulations conducted with ANSYS® software against simulated data generated by the software, enabling a comprehensive analysis of heat transfer mechanisms. The results reveal that the LSTM neural network is highly effective, achieving low root mean square error (RMSE) values and processing data more efficiently compared to traditional numerical methods. This dissertation proposes a metamodel that maintains prediction accuracy while significantly reducing computational costs compared to conventional simulations. This approach has the potential to enhance thermal monitoring in industrial processes, optimizing production and improving machining quality. Additionally, the study contributes to Sustainable Development Goal (SDG) No. 9 – Industry, Innovation, and Infrastructure – by promoting innovative technologies that strengthen industrial competitiveness and sustainability.
- ItemUma proposta para medição in-line da distribuição do tamanho de gotas em escoamentos de emulsões e seu desempenho(Universidade Federal do Espírito Santo, 2024-12-03) Pimentel, Cláudio Benincá; Loureiro, Bruno Venturini; Ramos, Rogério; https://orcid.org/0000-0003-4493-2435; Siqueira, Renato do Nascimento; Silva, Fabricio Soares daOil production is generally associated with the co-production of water, and its proportion increases as wells mature. Flow disturbances such as bends, valves, and equipment, which are crucial for controlling production in a safe and sustainable manner, increase shear stresses during flow, leading to the formation of stable emulsions due to the breakage of water droplets dispersed in the oil. Stable emulsions are unfavorable for the oil and gas industry as they hinder the phase separation process (oil/gas/water), resulting in higher consumption of chemical inputs and increased maintenance costs. The efficiency of the separation process is associated with the Droplet Size Distribution (DSD). However, most DSD measurement instruments currently operate through sampling, which exposes the emulsion to the risk of altered characteristics during sample handling. In this study, a device is proposed for measuring DSD using in-line optical microscopy, obtaining DSD through a computer vision-based algorithm from micrographs of droplets dispersed in the emulsion. Experimental procedures for commissioning and performance evaluation of the device, comparing it with conventional DSD measurement techniques, are carried out in a laboratory-scale emulsion experimental circuit available at the Center for Studies in Oil&Gas Flow and Measurement- Núcleo de Estudos em Escoamento e Medição de Óleo e Gás (NEMOG/UFES). The results obtained with the device demonstrate its ability to provide accurate in-line DSD information for water-in-oil emulsions, though with a more limited measurement range compared to the laser diffraction technique. The results are assessed using dimensionless numbers such as Reynolds and Weber, allowing for extrapolation across different scales. The developed device stands out for its simplicity, speed of measurement, and capability for in-line monitoring of emulsions.