Programa de Pós-graduação em Engenharia Mecânica

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Análise da aplicação de revestimento duro em aço carbono com o processo FCAW com e sem injeção de arame não energizado
(Universidade Federal de Goiás, 2023-08-17) Marques, Vitória Ferreira de Oliveira; Souza, Daniel; http://lattes.cnpq.br/2132578584168482; Ferraresi, Valtair Antonio; http://lattes.cnpq.br/0727420392683160; Ferraresi, Valtair Antonio; Souza, Daniel; Lima, Aldemi Coelho; Contin, Andre
Brazil is the world’s largest producer and exporter of sugar. One of the factors that directly impact the productivity of the sugarcane and alcohol industry is the maintenance of many equipment pieces that are subject to wear mechanisms. The application of hardfacing aims to reduce the wear of these equipment pieces and, consequently, increase their lifespan, reduce downtime, and production costs. To ensure the quality of the hardfacing, a proper selection of the deposited material and process parameters must be made. The objective of this study is to evaluate the resistance to abrasive wear of hardfacings using the FCAW (Flux-Cored Arc Welding) process, both self-shielded and with the addition of non-energized wire, while also assessing two interpass temperatures between weld beads (50°C and 200°C). The goal is to improve wear resistance and reduce the occurrence of solidification cracks. Three types of consumables (FeCrC, FeCrC+Nb, and FeCrC+Ti) with a diameter of 1.6 mm were used. FeCrC was used for the energized wire, while FeCrC+Nb and FeCrC+Ti were used for the non-energized wire. The base metal used was SAE 1045. Test specimens were constructed for wear evaluation in the laboratory using a Rubber Wheel Abrasion Tester in accordance with ASTM G65-91 standard. Wear evaluation was performed based on mass loss. Hardness and microstructure analyses of the coatings were also carried out. The best results for resistance to abrasive wear were obtained with the combination of FeCrC and FeCrC+Ti (nonenergized wire). It showed better performance at both interpass temperatures compared to other wire combinations. In all combinations, the presence of M7C3 carbides was observed. The combination of FeCrC and FeCrC+Ti showed the presence of titanium carbides (TiC), while the combination of FeCrC andFeCrC+Nb exhibited niobium carbides (NbC). All combinations with an interpass temperature of 200°C demonstrated higher wear resistance compared to those with an interpass temperature of 50°C.
Análise termo fluidodinâmica de ambientes com ar-condicionado usando o código livre OpenFOAM
(Universidade Federal de Goiás, 2023-08-28) Beghelli, Júlio Modesto; Moreira, Leonardo de Queiroz; http://lattes.cnpq.br/4443143323495371; Mariano, Felipe Pamplona; http://lattes.cnpq.br/4538460201961283; Mariano, Felipe Pamplona; Moreira, Leonardo de Queiroz; Silveira Neto, Aristeu da; Santos, Dyrney Araújo dos
Ventilation, cooling and heating systems have become indispensable for occupied environments that demand thermal comfort. Thermal comfort has a direct impact on productivity, well-being, health and also on energy consumption, given that by reaching the ideal room temperature, the air conditioning reduces the compressor’s operating time. Computational Fluid Dynamics is an important tool for the study of fluid flows, because with its use it is possible to evaluate the behavior of a given fluid applied under conditions established by the user. At first, in the present research, a thermal comfort study is carried out, using the OpenFOAM software, under conditions similar to those of a reference article, in order to compare the results and validate the OpenFOAM algorithm. In the reference article, a proprietary software which requires the acquisition of a license was used, while OpenFOAM is a open source software. Therefore, this study opens opportunities for analysis of heating, ventilation and air conditioning (HVAC) systems with the use of an accessible program, allowing the optimization of the climatization of a place. Next, the optimization of ventilation systems is evaluated through a factorial design that changes the air inlet and outlet positions, in addition to the insufflation speed. It is observed that the superior positions provided the best thermal comfort results, according to the Air Diffusion Performance Index (ADPI). Finally, the behavior of a air conditioner split Hi Wall type, based on ADPI, is investigated. The results provide information that ,for environments with an exhaust fan, lower the supply speed, greater the thermal comfort. As for environments without exhaustion, ADPI is better when the air intake velocity is higher.
Avaliação de resistência mecânica e análise de forma geométrica de elementos de fixação por rosca fabricados através de manufatura aditiva
(Universidade Federal de Goiás, 2023-08-31) Prado, Thiago Menezes do; Viana, Rhander; http://lattes.cnpq.br/5270141650315822; Cunha, Daniel Fernandes da; http://lattes.cnpq.br/7364532451621106; Cunha, Daniel Fernandes da; Ziberov, Maksyn; Medeiros, Everton Coelho de; Viana, Rhander
The work addresses the mechanical tensile strength of internal fillets in specimens manufactured in PLA and ABS from additive manufacturing by Fused Deposition Modelling (FDM). Test specimens measuring 30 x 30 x 20 mm were manufactured in PLA and ABS with a 3D printer model Ender 3 V2. The through hole of the specimens has measurements M12 x 1.75. Varied parameters used were: infill (p), number of walls (w) and height of the layers (h), to enable the understanding of how the mechanical resistance of the material is affected. Thus, the present study aimed to compare the mechanical resistance of PLA and ABS polymers through tensile tests, defining which material has greater resistance and with low production cost from 3D printing. The tensile tests were carried out using a tensile machine with a maximum capacity of 600 kN, which gradually applied tension to the specimens until the material fractured or ruptured. For the result analysis, relation of resistance from the specimens was verified graphically (force x time) and statistically (ANOVA), judging the influence of variables in individual and collective content in the achieved results. Pieces printed in PLA showed a higher quality of mechanical resistance compared to those made from ABS material when graphic results obtained were verified. As a statistical result, the ANOVA analysis identified the factor with greatest influence on tests were infill (P%), being preponderant both individually and collectively, when analyzing its influence with other two variables.
Efeito da temperatura de intercamada e da adição de arame frio em manufatura aditiva por deposição a arco em aço carbono
(Universidade Federal de Goiás, 2023-02-24) Lopes, Gustavo de Castro; Ferraresi, Valtair Antonio; http://lattes.cnpq.br/0727420392683160; Ferreira Filho, Demostenes; http://lattes.cnpq.br/2814935331164390; Ferreira Filho, Demóstenes; Souza, Daniel; Reis, Ruham Pablo; Ferraresi, Valtair Antônio
Additive Manufacturing by Arc Deposition (ADM) consists in the manufacture of metallic preforms from the deposition of multilayer weld beads on a substrate, that is, from a three dimensional model, the object is divided into layers defining the trajectories in which the addition of metal will be made, with the use of a robotic manipulator. This method has advantages such as a high deposition rate and the possibility of manufacturing parts of large proportions, compared with other methods. However it still requires studies to consolidate the technique and potential for improvement and development of new procedures, such as filling strategies and cooling processes between deposited layers. The objective of this work is to study the influence of the addition of cold wire in the MADA process, comparing it with the deposition made with a single wire, observing mechanical properties such as tensile strength, hardness, in addition to the cooling time for different interpass temperatures and the geometry of the manufactured parts. A GMAW (Gas Metal Arc Welding) system was used coupled to a Motoman HP20 robotic manipulator, with multiple wires of 1.6 mm in diameter for the energized wire and 1.0 mm for the cold wire, both classified as ER70S-6. The feed speed of the cold and energized wires was 1.5 m/min and 3.0 m/min, respectively. To measure the temperature, an MLX90614ESF-DCI sensor was used, connected to an Arduino system. In addition, a mixture of Argon with 25% of Carbon dioxide was used as a shielding gas with a flow rate of 25 L/min. In order to manufacture the specimens for the tensile test, 20 layers were superimposed in a straight line, forming a wall, varying the interpass temperature between each layer, using 100ºC, 150ºC and directly, with no waiting interval between layers. The walls were made, later it was production of specimens for tensile tests was carried out, using a CNC machining center. In the preparation of the bodies for hardness tests, the same methodology was followed, followed by the sanding and polishing process. In general, a shorter cooling time was observed for the walls manufactured with the addition of cold wire when compared to depositions with a single wire. In addition, it was noted that the cold wire also influences the height and thickness of the pieces. In the mechanical tests, the cold wire did not significantly influence the hardness values. The highest values were found in the 100ºC samples. For the tensile tests, it was observed that, in general, the addition of cold wire tended to increase the maximum tensile strength of the samples.
Efeito do gás de proteção e de tratamento térmico no desgaste de revestimentos de inconel realizados pelo processo GMAW
(Universidade Federal de Goiás, 2023-01-28) Kihara, Eliane Alves; Murray, Henara Lillian Costa; http://lattes.cnpq.br/8973820249465087; Ferreira Filho, Demóstenes; http://lattes.cnpq.br/2814935331164390; Ferreira Filho, Demóstenes; Souza, Daniel; Murray, Henara Lillian Costa; Alano, José Henrique
In coastal and offshore installations, deterioration of materials due to corrosion can reduce reliability and increase the cost of maintaining engineered components. However, it is known that the surface properties of materials can be improved by applying protective coatings on the substrate, thus prolonging the useful life of engineering components in severe environments, it is worth mentioning the best costeffectiveness when performed with more noble materials, maintaining the body of the part in lower cost material, and providing sur-faces with desired properties at a more accessible cost. A nickel alloy commonly used in the coating process is Inconel 625, because, subjected to severe conditions, it has excellent mechanical properties and resistance to corrosion at elevated temperatures. Among the various coating techniques, arc welding processes are suitable methods due to their good deposition rate and reliability, but they limit the application with inert shielding gases. Thus, this work aims to evaluate the effect of shielding gas and heat treatment on the wear of coatings of Inconel 625 deposited by the GMAW process on a carbon steel surface with the intention of selecting the parameters that will provide better mechanical properties for applications in harsh environments providing improvements in maintenance and manufacturing costs. Coatings were carried out on A36 carbon steel plate with two mixtures of shielding gases (Ar + 25%CO2 and Ar +25%He), analysis was carried out on samples as welded and after heat treatment (heating for 1 h at 1000 °C and air cooling). To evaluate the coatings, Vickers hardness tests (HV), scanning electron microscopy (SEM), energy dispersion spectrometer (EDS), wavelength dispersion spectrometry (WDS), confocal wear tests by the alternating sliding method were performed. between the flat surface and the spherical counter in saline solution (10% iodized salt). The samples that used He gas showed a higher wear rate compared to the samples that used CO2 gas, this result is attributed to the formation of Laves phase and surface embrittlement. As for the heat treatment in both gases, there was a reduction in segregation and a tendency to reduce the surface hardness and reduce the wear rate.
Efeito do tempo de austenitização na evolução da microestrutura e comportamento mecânico dos aços inoxidáveis UNS S42000 e UNS S41003
(Universidade Federal de Goiás, 2023-02-28) Alves, Renata Rodrigues; Cunha, Daniel Fernandes da; http://lattes.cnpq.br/7364532451621106; Cunha, Daniel Fernandes da; Figueireido, Kleber Mendes de; Contin, André; Labiapari, Wilian da Silva
Quenching is one of the most common methods of heat treatment and aims to increase the mechanical strength of the material by transforming austenite into martensite at high temperatures, followed by rapid cooling. The formation of martensite depends on various factors, such as the time the material is held at the austenitization temperature. In the context presented and with the aim of contributing to a better understanding of the microstructure evolution and mechanical behavior of stainless steels with different carbon contents, this study aimed to investigate the effect of austenitization time followed by quenching treatment. The materials studied were low carbon steel, commercially known as UNS S41003 or 410D, and medium carbon steel, commercially known as UNS S42000 or 420A. Two heat treatment conditions were studied, in the first one, the steels were austenitized at 1000 ℃ with varying austenitization time (5 min, 30 min, 60 min, 120 min, and 240 min) and then quenched in water, while in the second condition, the samples were annealed at 800 ℃ and then austenitized at 1000 ℃ with varying austenitization time (5 min, 30 min, 60 min, 120 min, and 240 min), and finally quenched in water. Thermodynamic simulations were performed using Matcalc software to evaluate the relative stability of phases and precipitates under equilibrium conditions. It was observed that both steels would be austenitized at 1000 ℃, and the carbides dissolved, however, it was identified that the carbide dissolution depends on the austenitization time when outside of equilibrium. Despite the low carbon content, austenitization of the 410D steel was possible due to the presence of austenitizing elements such as Ni, Mn, and N, thus, both steels showed a martensitic structure after the water quenching process. It was possible to observe that with an increase in austenitization time, the martensite lath increased due to the gradual increase in grain size. The distribution of the prior austenitic grain size was found to be heterogeneous for longer times, related to the dissolution of carbides. In addition to presenting a similar microstructural evolution, both steels also exhibited similar mechanical behavior, with the material softening as the grain size increased, associated with the freer dislocation movement with increasing austenitization time. Finally, the obtained data on prior austenitic grain size and hardness were treated with a 95% confidence level. It is believed that the results of this study provide a foundation for a better understanding of the austenitization time parameter in the heat treatment of stainless steels.
Efeito dos parâmetros de usinagem na usinabilidade dos aços inoxidáveis 410D e 420A ferrítico e martensítico no processo de eletroerosão por penetração
(Universidade Federal de Goiás, 2023-02-27) Cunha, João Bosco da; Viana, Rhander; http://lattes.cnpq.br/5270141650315822; Cunha, Daniel Fernandes da; http://lattes.cnpq.br/7364532451621106; Cunha, Daniel Fernandes da; Oliveira, Deborah de; Viana, Rhander; Contin, André
Electrodischarge Machining is an unconventional machining process that has served as an alternative for machining difficult-to-machine materials and complex geometries by removing material through electrical discharges. In the electrical discharge machining (EDM) process, it is necessary to know the parameters that affect material removal, electrode wear and the surface finish of the workpiece. Knowing these parameters provides greater productivity and reduction of costs in machining process. In this context, this work seeks to establish, through a design of experiments (DOE), an analysis about the behavior of the process with different values of electrical current, electrical discharge time and the working GAP during machining AISI stainless steels 410D and 420A, supplied in annealed state. After tempering process, it changes its ferritic to martensitic microstructure. It was statistically verified that electrical current affected material removal rate (MRR), electrode wear rate (EW) and surface roughness. These data confirms literature review about using higher currents for rough machining, sacrificing the electrode tool for increasing material removal process, and smaller electrical currents for finishing machining parameters, guaranteeing the final geometry and better surface quality of the machined cavity. Heat treatment is shown by this research to have no significant influence on material removal rate, electrode wear and surface roughness.
Estudo experimental do leiaute de disposição dos materiais de absorção sonora em uma sala de aula
(Universidade Federal de Goiás, 2023-02-16) Assis, Leandro Neves de; Fagundes Neto, Marlipe Garcia; http://lattes.cnpq.br/6303674803792521; Fagundes Neto, Marlipe Garcia; Nunes, Maria Alzira de Araújo; Badan, Marco Aurélio Brazão Costa
Classrooms have the function of promoting learning through oral communication and listening. Thus, one of the main characteristics that determine the success of this function is the acoustic quality of classrooms. Speech intelligibility is one of the most relevant parameters and can be improved by minimizing external noise and reducing reverberation. One tactic to decrease the reverberation of a room is to dampen sound energy by using absorbent materials such as: padded chairs, curtains, carpets, and sound absorbing panels (SAP). However, the influence of the positioning of the elements, especially the SAP, is little studied. For the experiments of the positions with the SAP, Room 108 was used, which is located in the Mechanical Engineering building, campus II of UFG and, based on ISO 3382-2, 2 distinct points were selected for the sound source and 6 distinct points for the receptor. The data obtained was analyzed by the analysis of variance technique, aiming at identifying the most significant factors for the acoustic performance of the environment, since the following work has the general objective of investigating the arrangement of sound absorption materials in classrooms, through the acoustic parameters obtained, such as Reverberation Time, Brightness, Bass Ratio, Clarity and Definition. The results showed that the higher frequencies provided better responses in all parameters. Furthermore, in general, it was observed that the configuration with slabs placed closer to the frame and further back in the room stood out as having the best acoustic performance for the room studied. On the other hand, the configuration with slabs only closer to the board showed the worst responses, thus being characterized as the worst layout for the same room.
Modelagem e implementação de uma planta didática de manufatura robótica inspirada em planejamento automático
(Universidade Federal de Goiás, 2023-06-30) Alves, Weslley da Silva; Fonseca, João Paulo da Silva; http://lattes.cnpq.br/5217261758266411; Fonseca, João Paulo da Silva; Tavares, José Jean Paul Zanlucchi de Souza; Soares, Anderson da Silva
Current manufacturing systems have been undergoing significant technological advancements, particularly in the field of production planning and automation. The Fourth Industrial Revolution, or Industry 4.0, has already begun to enable technological innovations across various domains, especially in the manufacturing and services industries. There has been a noticeable surge in research on artificial intelligence techniques involving manufacturers seeking efficiency and speed. To achieve 'intelligent' behavior, it is inevitable to implement techniques for automated problem-solving, enabling some decision-making by the equipment and devices themselves. Automated planning, also known as 'automated planning' or 'AI Planning' in English, defines a specific type of state transition problem in which the goal is to find an admissible sequence of actions to bring the system from a certain initial state to a desired final state. The use of automated planning applied to manufacturing processes is gaining prominence in the academic sphere due to the potential to expand the use of techniques in real-world applications in modern industry. This work aims to primarily analyze data from the integration of automated planning solutions into real systems and describe a practical example based on a didactic plant that simulates a production line in a factory composed of individual cells. For the project's implementation, a programmable logic controller (PLC) was used as a model of real systems used in industrial automation, and the assembly and description steps of each station are presented. The language used for modeling the planning domain was the 'Planning Domain Definition Language' (PDDL), through the online platform 'PDDL Editor,' which is part of a set of online tools for AI Planning called 'Planning.Domains.' The modeling was distributed across five stations to facilitate solving the proposed problem for each station, thus generating five solution plans, one for each station. The results achieved from the domain modeling method in manufacturing using an online automated planning tool included the generation of solution plans for the proposed scenarios and practical implementation on the didactic bench using the 'Sequential Function Chart' (SFC) programming language. The proposed approach was compared with the classical approach, which concentrated programming logic on the PLC and used the Ladder programming language, highlighting the potential of using automated planning for Industry 4.0-related topics.
Simulações computacionais de escoamentos sobre pás de turbinas eólicas de eixo vertical utilizando em conjunto os métodos pseudoespectral de Fourier e o da fronteira imersa
(Universidade Federal de Goiás, 2023-02-27) Monteiro, Lucas Marques; Mariano, Felipe Pamplona; http://lattes.cnpq.br/4538460201961283; Mariano, Felipe Pamplona; Silva, Ana Lucia Fernandes de Lima e; Silveira Neto, Aristeu da
Changes in climate behavior over the years, accompanied by a strong increase in energy demand by countries around the world, have led authorities and researchers to improve the search for renewable, clean energy sources with low environmental impact. The development of vertical axis wind turbines is an assertive and efficient option, especially in places with low wind speeds and unavailability of large spaces. Then, the present work presents and analyzes the main fluid dynamic aspects related to vertical axis wind turbines. The objective is to investigate and estimate the performance parameters, as well as to evaluate the flow dynamics on these machines. For this, it is proposed to verify the applicability of the IMERSPEC methodology, responsible for numerical and computational modeling of these flows. It is a high-order convergence methodology with low computational cost, when compared to other high-order methodologies, resulting from the coupling of the Fourier pseudospectral method and the immersed boundary method. The imposition of the rotational movement on the turbine blades is guaranteed by a specific subroutine, implemented from a mathematical model, developed and presented in the present work. This subroutine, added to the computational platform together with the IMERSPEC methodology, contemplates the fluid-structure interaction between the turbine and the flow, allowing the estimation of performance coefficients, such as power, torque, normal force, tangential force, lift force and drag force. Initially, to validate the proposed methodology, two-dimensional flow simulations are carried out on a NACA 0012 airfoil for a Reynolds number equal to 1000. From the proposed numerical simulations, convergence and good agreement of the results presented in relation to the reference works are obtained. The behavior of the flow over the airfoil and the different modes of formation of the wakes are evaluated by the fields of velocity, pressure and vorticity, as a function of the angle of attack. Furthemore, to verify the accuracy and potentiality of the IMERSPEC methodology, an analysis is performed, therefore, for fluid dynamic problems in vertical axis turbines, still two-dimensional. The solidity of the turbine is investigated through the simulation of flows over turbines with one and three blades, composed by the airfoil NACA 0015. It also presents the influence of increasing the Reynolds number, between 100 and 1000, for flows over turbines of a single blade. In general, the results presented guarantee, with reliability and physical coherence, the applicability of the methodology in two-dimensional flows of this type.
Tratamento de superfície em substratos de aço da indústria farmacêutica via laser de CO2
(Universidade Federal de Goiás, 2023-08-31) Martins, André Carvalho; Cunha, Daniel Fernandes da; http://lattes.cnpq.br/7364532451621106; Contin, André; http://lattes.cnpq.br/5450987692265022; Contin, André; Bertholdi, Jonas; Ferreira Filho, Demóstenes; Cunha, Daniel Fernandes da
AISI 304 stainless steels play a crucial role in the pharmaceutical industry due to their resistance to chemical reactivity. However, their wear resistance is limited in high-temperature and highpressure environments. Laser treatment emerges as a promising approach to enhance their properties. In this study, a low-cost 100 W CO2 laser is used for the surface treatment of AISI 304 steels, with the addition of carbon black powder. The results showed a significant increase in surface hardness after laser treatment compared to the untreated substrate. EDS analyses revealed the presence of carbon on the surface of the substrates. In addition to the increased surface hardness, the coefficient of friction of the laser-treated samples was reduced when compared to the reference substrate. Ultimately, carbon black acted as a photoabsorbing material for radiation, a source of carbon for increasing surface hardness, and as a solid lubricant. These results demonstrate the viability of using a low-cost CO2 laser as an efficient, versatile, and rapid alternative to improve the properties of materials employed in the pharmaceutical industry.
Utilização de inteligência artificial para análise modal de uma viga engastada sob escoamento em túnel de vento
(Universidade Federal de Goiás, 2023-02-04) Rodrigues, Pedro Augusto Dias; Kitatani Junior, Sigeo; http://lattes.cnpq.br/9419723461067210; Fagundes Neto, Marlipe Garcia; http://lattes.cnpq.br/6303674803792521; Fagundes Neto, Marlipe Garcia; Pena, José Luiz Oliveira; Colherinhas, Gino Bertollucci; Kitatani Júnior, Sigeo
Wind turbines suffer severe damage due to excessive wind loads or inadequate maintenance conditions, and catastrophic failures often occur causing huge losses. A structure, such as a wind turbine, can be monitored and evaluated through its modal characteristics, where natural frequencies, for example, are characteristics that are independent of operating conditions. They change only in case of damage, i.e. when stiffness and mass change. However, for the application of modal analysis, several sensors distributed in the structure are required, which involves high instrumentation costs. In view of this, it is proposed the use of modal analysis techniques integrated with virtual sensors, which, unlike real/physical sensors, are obtained through models. In this work, the virtual sensors are determined by using an artificial intelligence of the neural network type, which together with the modal analysis allows to obtain the modal characteristics: natural frequencies, modal shapes and damping. For this purpose, it is proposed to study a fixed Euler Bernoulli beam, an approximation model of a wind turbine, where the flow loads are generated through a wind tunnel with a speed controller. The flow velocities analyzed over the beam ranged from 10 to 20 m/s. The virtual sensor for operational modal analysis was modeled using a dynamic neural network where configurations of delay number and number of neurons in the hidden layer were investigated. In sequence, the modal characteristics of the Euler Bernoulli beam are compared using experimental modal analysis, situation in which the input is known and measured, and operational modal analysis, configuration where the input is unknown and not measured. For comparative analysis, the natural frequencies obtained in the different configurations and modal techniques showed good results when compared with the values of the Euler Bernoulli beam. For the modes, the Modal Assurance Criterion (MAC) was used, where when analyzing each independent result, the MAC returns excellent modal results, but when performing a comparative analysis of the different configurations and techniques, the MAC showed low correlation. Finally, the damping ratio showed an increase for higher flow velocities, but further investigations should be carried out in future works using other operational modal analysis techniques.

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