http://repositorio.ufc.br/handle/riufc/22104 2026-04-09T23:09:42Z http://repositorio.ufc.br/handle/riufc/83134 Título: Desempenho e segurança de cilindros de pressão Tipo 4 para armazenamento de hidrogênio: uma abordagem de simulação computacional Autor(es): Rodrigues, Milena Peixoto Abstract: Within the scope of the safety and performance of Type 4 pressure vessels for green hydrogen storage, the structural, thermal, modal, and fracture response was analyzed using computational simulation via ANSYS Workbench, based on the criteria of the ASME Section X, Appendix 8 standard. A cylinder composed of an HDPE liner, T700/Epoxy composite, and an Aluminum 6061 T6 boss (outer radius 150 mm, length 650 mm) was modeled using 1/8th symmetry. The analyses included: static structural simulation under 70 MPa internal pressure; steady-state thermal analysis with 85°C in-ternal and 28°C external temperatures; modal analysis for identifying natural frequenci-es; and fracture analysis involving the introduction of a 1 mm x 3 mm semi-elliptical crack in the composite. The structural analysis results indicated a maximum principal stress of 1630 MPa before the crack (exceeding the estimated allowable limit of ~991 MPa) and 1.397E4 MPa at the crack tip, with a maximum deformation of ~14 mm. The thermal analysis confirmed operation at the 85°C limit in the liner. The modal analysis identified the first 6 natural frequencies (between ~1083 Hz and ~2570 Hz), with slight alterations due to the crack. The fracture analysis resulted in maximum Stress Intensity Factors of KI ≈ 142 MPa√m, KII ≈ ±30 MPa√m, and KIII ≈ -46 MPa√m (absolute va-lue), indicating critical mixed-mode loading in the depth direction. Therefore, computa-tional simulation is demonstrated as an essential tool for assessing safety, identifying critical stress and temperature points near standard limits, and quantifying the signifi-cant impact of defects, highlighting the need for design optimization. Tipo: TCC 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/83133 Título: Estudo da suscetibilidade à corrosão de aços carbono em meio de NaCl 3,5% utilizados como armaduras de tração em risers Autor(es): Pontes, Nívea Maria Ribeiro Abstract: This study aimed to evaluate the corrosion susceptibility of carbon steels used as tensile reinforcements in flexible risers, which are critical structures in offshore operations within the oil and gas industry. The research focused on two types of carbon steel, with carbon contents of 0.27% and 0.80%, under simulated exposure conditions to corrosive environments using sodium chloride (NaCl) solution with and without carbon dioxide (CO₂), and subjecting the samples to temperatures of 25 C and 40 C. To this end, electrochemical tests were conducted, including Open Circuit Potential (OCP), Electrochemical Imp edance Spectroscopy (EIS), Potentiodynamic Polarization (PP), and Electrochemical Frequency Modulation (EFM), along with microstructural analysis before and after testing. The results showed that the steel with higher carbon content (0.80%C) exhibited greater susceptibility to corrosion, especially in the presence of CO₂, due to the formation of unstable corrosion products and lower resistance to current flow. In contrast, t he 0.27%C steel demonstrated superior performance, as evidenced by larger semici rcles in Nyquist plots and lower corrosion current density. Microstructural analysis supported the electrochemical data, revealing greater degradation on the surfaces of the higher carbon specimens. These findings underscore the importance of selecting app ropriate carbon content in steels used in aggressive environments, contributing to corrosion mitigation strategies and enhancing the durability of structural components. Tipo: TCC 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/83132 Título: Recuperação de minerais de altos valores em refratários siderúrgicos de pós-consumo. Autor(es): Fernandes, Thiago Nascimento Abstract: Refractory materials are of critical importance to various industrial sectors, particularly the steel industry, which accounts for 70% of consumption, followed by the cement industry with 9%, and non-ferrous metallurgy with 4%, among others. Over the years, a reduction in both production and specific consumption of refractory materials has been observed, mainly due to improvements in the operational parameters of end users and the development of new refractory materials with enhanced thermal and mechanical properties. Nevertheless, despite the decline in these indicators, certain challenges persist within the refractory sector. The main issues include the disposal methods of post-mortem refractory materials and the CO₂ emissions associated with the production of virgin raw materials. For instance, zirconia (ZrO₂) is noted for having the highest production cost and carbon emissions during its manufacturing process. Based on this scenario, the present study qualitatively investigates a hypothesis regarding particle size ranges that exhibit higher concentrations of zirconia (ZrO₂), tabular alumina (Al₂O₃-⍺), fused magnesia (MgO), and silicon carbide (SiC), derived from their respective post-consumer refractory products. Following four processing stages—comminution, screening, and particle size classification—it is hypothesized that minerals with higher hardness (ZrO₂, Al₂O₃-⍺, and SiC) tend to concentrate in coarser fractions, specifically above 9.5 mm. Meanwhile, fused MgO, with intermediate hardness, is found in higher concentrations in particle size fractions above 2.360 mm. Tipo: TCC 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/83129 Título: Análise de óleo lubrificante como ferramenta de diagnóstico preditivo em caixas multiplicadoras de aerogeradores: estudo de caso na empresa 8.2 Renewables Brasil. Autor(es): Oliveira, Gustavo Carvalho de Abstract: The growing demand for wind energy drives the need for maintenance strategies that ensure the availability and reliability of wind turbines. The gearbox is one of the most critical and costly components of this system, operating under severe conditions. This study aims to demonstrate the effectiveness of lubricating oil analysis as a predictive maintenance tool in gearboxes of Siemens-Gamesa G97 wind turbines with 12 years of operation. Based on the author's practical experience at the 8.2 Renewables Brasil company, laboratory reports of synthetic oil samples (Shell Omala S3 Wind) were interpreted, analyzing physicochemical parameters and the presence of contaminants. The methodology consisted of classifying the results into "Normal", "Attention", and "Replace" categories, based on pre-established technical limits. The results of a case study involving six turbines revealed that the main indicators leading to corrective actions were elevated zinc (Zn) content, indicative of additive degradation, and high solid particle contamination (ISO 4406 standard). The study concludes that the continuous monitoring of the lubricant allows for the early detection of conditions that lead to severe failures, enabling planned corrective actions that reduce operational costs, increase component lifespan, and optimize the maintenance management of wind assets. Tipo: TCC 2025-01-01T00:00:00Z