Engenharia Mecânica
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/23
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9 resultados
Resultados da Pesquisa
- Effect of hybrid manufacturing (am-machining) on the residual stress and pitting corrosion resistance of 316L stainless steel(2022-10-05) Ed Claudio Bordinassi; MHURCHADHA, S. U.; SERIACOPI, V.; Sergio Delijaicov; LEBRÃO, S. M. G.; THOMAS, K.; BATALHA, K.; RAGHAVENDRA, R.© 2022, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The use of additive manufacturing (AM) has grown exponentially in recent years and has many advantages, including feasibility, over other conventional processes in many current applications. The use of a second process, for example, machining, improves the surface finish and in this case, the use of two processes is known as hybrid manufacturing. Heat treatments are often performed on parts generated by the AM process, mainly to relieve the residual stresses generated, but for some materials, this can decrease the pitting corrosion resistance of the parts. The objective of this study is to analyze the effect of hybrid manufacturing (AM + machining) on residual stresses and pitting resistance corrosion, which can bring advantages to piece properties without the use of heat treatment. 316L stainless steel parts are generated by direct laser metal sintering (DLMS), with subsequent milling using a complete factorial planning for the design of the experiments. The cutting speed, feed rate, cutting depth, use of the cutting fluid and laser power in the DLMS process are all varied. Residual stresses are measured by X-ray diffraction and the blind hole method, with polarization curves raised by a potentiostat. The results show that it is possible to reduce the residual surface stresses in the parts, even for compressive stresses, and to improve the pitting corrosion resistance, when compared to the part without milling, depending on the cutting parameters used.
- Optimal coordination strategy to form and dissolve truck platoons on a highway stretch(2022) DE SOUZA MENDES, A.; Fabrizio Leonardi; DE TOLEDO FLEURY, A.© 2022, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.This paper presents a coordination strategy to optimally form and dissolve N-truck platoons on a highway stretch. Truck platooning, a set of trucks driving with small inter-vehicle distances, can benefit the transportation sector by reducing the overall fuel consumption and greenhouse gas emissions while increasing traffic throughput. However, different itineraries and delivery time restrictions may limit the opportunities to from platoons on a large scale. Therefore, a coordination strategy must be capable of merging scattered trucks and splitting the platoon considering the constraints from each participant to avoid penalties. To address this issue, an optimization problem is formulated to provide optimal speed profiles for an unlimited number of trucks during the merging, platooning and splitting phases of the coordination. An equivalent single stretch representation is presented to simplify complex road networks using appropriate merging and splitting constraints. The resulting optimal speed profiles are presented for 2, 3 and 10 trucks highlighting the capability to handle different desired traveling speeds without compromising the itinerary of each truck and allowing the overtake of trucks directly in the optimization problem. Sensitivity analyses are used to investigate the savings potential according to the main parameters of the coordination. Finally, the proposed algorithm is evaluated in a simulation study using validated vehicle and consumption models with real road topography data. In a 100 km Brazilian highway stretch, scenarios with two and three scattered trucks with substantial initial separation distances are evaluated and present energy efficient maneuvers under the proposed coordination strategy.
- Thermodynamic analysis and optimization of a multi-stage compression system for CO2 injection unit: NSGA-II and gradient-based methods(2021-10-10) ALLAHYARZADEH-BIDGOLI, A.; DE MELO, P. E. B.; DEZAN, D. J.; SALTARA, F.; SALVIANO, O.; YANAGIHARA, J. I.© 2021, The Brazilian Society of Mechanical Sciences and Engineering.The injection of CO2 into oil reservoirs is used by the oil and gas industry for enhanced oil recovery (EOR) and/or the reduction of environmental impact. The compression systems used for this task work with CO2 in supercritical conditions, and the equipment used is energy intensive. The application of an optimization procedure designed to find the optimum operating conditions leads to reduced energy consumption, lower exergy destruction, and reduced CO2 emissions. First, this work presents two thermodynamic models to estimate the amount of power necessary for a multi-stage CO2 compression system in floating production storage and offloading (FPSO) using accurate polytropic relationships and equations of state. Second, a thermodynamic analysis using the first and second laws of thermodynamics is conducted to identify possible improvements in energy consumption and the sources of the compression unit’s irreversibilities. In the final step, optimization procedures, using two methods with different approaches, are implemented to minimize the total power consumption. As the number of stages and the pressure drop between them influence the total power required by the compressors, these are considered as the input parameters used to obtain the inlet pressure at each stage. Three different compositions with variations in CO2 content, i.e., pure CO2, pure CH 4, and 70% CO2 + 30% CH 4, are also investigated as three different operating scenarios. The optimal configurations and pressure ratios result in a reduction in power consumption of up to 9.65%, mitigation of CO2 emissions by up to 1.95 t/h, and savings in exergy loss of up to 23.9%, when compared with conventional operating conditions.
- Could an absorption refrigeration system be driven by the engine exhaust gas and cooling fluid of a minibus?(2021-12-05) RANIERI, M. A.; MANIERI, G.; MADY, C. E. K.; Cyro Albuquerque© 2021, The Brazilian Society of Mechanical Sciences and Engineering.This study evaluates the possibility of recovering energy from the cooling and exhaust systems of an internal combustion engine as a source input for an absorption refrigeration system. Sensors were installed in a minibus to measure the temperature and mass flow of the exhaust gas. Their signals, together with those of the vehicle’s built-in sensors, were acquired during tests under different conditions: warm-up, city route, and highway route. Simulations of a lithium bromide absorption refrigeration cycle were performed using the experimental data as input. In the model, a fraction of the engine cooling fluid and exhaust gas was considered as the generator’s energy source. Hence, recuperative heat exchangers were included with an auxiliary water circuit between the generator and exhaust system. The results showed an average cooling capacity of 1.5 kW during the initial warm-up phase, reaching 7.2 kW under road-route driving conditions. In the city, where minibusses are used most, a cooling capacity of 3.6 kW was found, that is, 68% of the cooling demand in vehicles in this category. To operate under these conditions and during the warm-up period, an alternative system would have to be added as an electrical heater. Moreover, the system requires a controller to bypass a fraction of the available exhaust gas during high engine demands.
- Phenomenological model of particulate matter emission from direct injection diesel engines(2005-07-05) ARGACHOY, C.; PIMENTA, A. P.A new phenomenological model is introduced by applying established conceptual models for direct injection combustion to develop a mathematical description of events. The model has the capability to predict particulate mass output, as well as a particulate mass history over a single combustion event. The model was developed in a Matlab-Simulink environment to promote modularity. Results of particulate mass output from single cylinder laboratory engine, and six-cylinder vehicular engine were used to determine the validity of the predictions made. Although predicted values do not perfectly match measured values, there is certainly reasonable agreement. Copyright © 2005 by ABCM.
- μ-synthesis for unmanned underwater vehicles current disturbance rejection(2011) DE SOUZA, E. C.; MARUYAMA, N.This note focuses attention on a novel approach to disturbance rejection when the μ-synthesis control procedure is applied to Unmanned Underwater Vehicles (UUVs). Environmental external disturbances simplify to ocean current for a totally submerged vehicle and greatly contributes for hydrodynamical loads and the tether cable disturbance. Our case scenario deals with the incorporation of the sea current disturbance to the plant model employed for control design. In the proposed design method, we substitute the structured unmodeled dynamics uncertainty, which is generally difficult to come up with and eventually utilized to represent external disturbances, by parametric uncertainty, relatively easier and straightforward to come by. The sea-current load parameters are, therefore, treated as parametric uncertainty and fit in the μ design framework. Assuming that both vehicle motion and current direction lie in the horizontal plane, the incoming (to vehicle) current vector sets a horizontal circumference sector in which it may vary. When in the 3D space, current uncertainty renders a cone in space. For validation purposes, the linear controller is simulated with the nonlinear vehicle model.
- Exergy efficiency on incremental stationary bicycle test: A new indicator of exercise performance?(2019-12-01) MADY, C. E. K.; IGARASHI, T. L.; Cyro Albuquerque; SANTOS-SILVA, P. R.; FERNANDWS, A. J.; HERNANDEZ, A. J.© 2019, The Brazilian Society of Mechanical Sciences and Engineering.The first and second laws of the thermodynamics were applied to the human body to evaluate the performance of subjects under different training levels. Ten cyclists were evaluated in the stationary bicycle with the indirect calorimetry analysis to obtain the metabolism on an energy and exergy basis. A distinguishing feature of this article is the evaluation of the exergy efficiency of the body with the knowledge of the real performed power and the internal temperature (measured tympanic temperature and calculated esophagus temperature). Regarding the skin temperature, an infrared camera was used to measure different parts of the body. Therefore, the phenomenological behavior of the body was assessed and used as a basis to apply the exergy analysis. Results indicate that the destroyed exergy can be an indicator of performance when compared with maximum oxygen consumption. Nevertheless, more experiments must be carried out to proper state if there is a correlation. Eventually, the exergy efficiency was calculated for all subjects, and its value was around 23 to 28%.
- Exergy efficiency on incremental stationary bicycle test: A new indicator of exercise performance?(2019-11-16) MADY, CARLOS EDUARDO KEUTENEDJIAN; IGARASHI, TATIANE LIE; Cyro Albuquerque; SANTOS-SILVA, PAULO ROBERTO; FERNANDES, TIAGO LAZZARETTI; HERNANDEZ, ARNALDO JOSEThe frst and second laws of the thermodynamics were applied to the human body to evaluate the performance of subjects under diferent training levels. Ten cyclists were evaluated in the stationary bicycle with the indirect calorimetry analysis to obtain the metabolism on an energy and exergy basis. A distinguishing feature of this article is the evaluation of the exergy efciency of the body with the knowledge of the real performed power and the internal temperature (measured tympanic temperature and calculated esophagus temperature). Regarding the skin temperature, an infrared camera was used to measure diferent parts of the body. Therefore, the phenomenological behavior of the body was assessed and used as a basis to apply the exergy analysis. Results indicate that the destroyed exergy can be an indicator of performance when compared with maximum oxygen consumption. Nevertheless, more experiments must be carried out to proper state if there is a correlation. Eventually, the exergy efciency was calculated for all subjects, and its value was around 23 to 28%.
- Effect of the hardening rules on the creep age forming prediction of 7050 aluminum alloy with experimental verification(2018) Oliveira M.C.; Delijaicov S.; Bortolussi R.© 2018, The Brazilian Society of Mechanical Sciences and Engineering.The creep age forming (CAF) has been used in the aerospace sector due to its attractive characteristics that allows producing a component with low residual stress. The process has been studied from the finite-element simulations which are used mainly to predict the springback. However, to accomplish the simulation, it is necessary to set the CAF constitutive equations in the finite-element software. In addition, it is also necessary to define the hardening rule which is applied to determine the creep strain. This work aims to investigate CAF applying the finite-element analysis with the time-hardening rule and strain-hardening rule and thus predicting creep strain, stress relaxation, and springback. The finite-element simulations were accomplished in dies with single and double curvatures and the blank’s material was the alloy AA7050. Furthermore, the Marin–Pao model was implemented in the MSC.Marc software through a user subroutine. This model was fitted to the creep experimental curves and it generated good agreement with the experimental data. The results of the simulations that used the time-hardening rule were similar to the strain-hardening rule, and therefore, if it had been chosen a hardening rule, it would not have generated a significant impact in the CAF simulation results. At the end, the simulated springback was compared to the experimental springback from the literature and the percentage error ranged from 0.46% to 15.33% that indicate the proximity with the literature data. Moreover, other experimental validation was performed, and when compared to the results of this methodology, the calculated error in springback was 6.3%.