Search

Fatigue crack growth tests are conducted to assess the efficacy of the stop-hole crack repair method. This straightforward and widely adopted technique involves drilling a hole at the crack tip and subsequently enlarging it using a pin inserted into the hole. A fracture mechanics-based model is proposed to estimate the extension of fatigue life achieved through the implementation of the stop-hole technique. The model’s predictions are validated using data obtained from fatigue crack growth tests conducted on both unrepaired and repaired M(T) specimens, following the guidelines outlined in the ASTM E647 standard. The error of the fracture mechanics-based model was 1.4% in comparison with the fatigue tests.

Two-phase transient flows in emptying processes of hydraulic pipelines with entrapped air have been studied in detail in the literature through the development of different mathematical models based on rigid column models. During literature review, it was found that transient flows representing pipeline emptying processes have been rarely studied by two-dimensional and three-dimensional analysis. This research begins demonstrating the behavior of air and water in pipelines during emptying processes, and the formulation of existing mathematical models, where two scenarios are considered: i) Emptying process of a branched hydraulic conduction with air valves, and ii) Emptying process of a simple hydraulic conduction without air valves. In this master thesis, two computational fluid dynamics (CFD) models were developed to study the hydraulic-thermodynamic parameters that occur in pipe emptying processes. An introduction to CFD modeling is performed for its use in the two-dimensional and three-dimensional analysis of two-phase transient flows. Subsequently, a 2D CFD model is performed to simulate Scenario No. 1 (branched hydraulic conduction with air valves), and a 3D CFD model is performed to simulate Scenario No. 2 (simple hydraulic conduction without air valves), described above. The geometric domains, meshing, boundary conditions, numerical schemes and calculation tolerances for the numerical solution of the Navier-Stokes equations for two-phase and compressible flows are defined for numerical processing. The 2D and 3D CFD models are validated with results obtained from experimental measurements carried out by other authors, and by means of a meshing sensitivity analysis. The CFD models show good correlation with the experimental results associated with pressure patterns, velocity, water column length, and allow to visualize in greater detail transient phenomena that are not captured by the mathematical models. These CFD models are compared numerically with their re

The use of better control strategies has a great interest in all kinds of industries in recent years since it allows better use of resources and therefore becomes an important factor in reducing costs associated with reprocessing and unnecessary spending of raw materials. This research evaluates the performance of a control strategy, in which the tuning parameters of a classic controller are supplied by a fuzzy logic algorithm (Fuzzy Gain Scheduling). the behaviour of the strategy is tested in a mixer-reactor system and is compared with that achieved through the implementation of a classic controller, a dynamic matrix system, and fuzzy logic control. In the results, it can be seen that the Fuzzy Gain Scheduling strategy presents a good behaviour, improving around 25% compared with the other alternatives, this added to the advantage of being able to include previous experience on the process, in the actions that are taken by the strategy to keep desired operating ranges. © 2022 School of Engineering, Taylor's University.

Los trenes de precalentamiento son redes de intercambiadores de calor usados en las refinerías de crudo. El desempeño adecuado de este sistema representa un hito importante para la competitividad de las refinerías porque les permite disminuir los costos y cumplir con las regulaciones normativas. La disminución de la eficiencia en los intercambiadores debido a la formación de fouling suscita problemas como: aumento en los costó de operación, mayor gasto de mantenimiento, disminución en la vida útil de los equipos, riesgos de integridad de activos y mayor producción de gases de combustión. La planeación de mantenimiento para los trenes de precalentamiento es crucial para un desempeño adecuado de las refinerías, sin embargo, esto también implica serios inconvenientes para los mantenedores pues no existe una guía general que pueda ser aplicada para programar las rutinas. En este trabajo se desarrolla una estrategia de mantenimiento para un tren de precalentamiento bajo la filosofía del Mantenimiento Centrado en Eficiencia Energética (MCEE), donde se busca integrar la información proveniente de los estudios de la segunda ley de la termodinámica con variables económicas para usar parámetros establecidos o crear nuevos, con el objetivo de planificar las labores de limpieza a los intercambiadores de calor según criterios técnicos, económicos y de beneficios hacia los otros intercambiadores de la red. Esta investigación destaca por utilizar el análisis mexogeno para individualizar las relaciones entre todos los elementos de la red. Además, se modifica un parámetro (J*) sumado a la introducción dos nuevos indicadores de mantenimiento (W y X), para simplificar la toma de decisiones mediante el uso de un diagrama criticidad y una matriz de criticidad. Los resultados obtenidos designan a cinco intercambiadores como críticos porque sus mal funcionamientos individuales representa un impacto significativo para el desempeño global del tren. Estos elementos se convierten en candidato