Percorrer por autor "Costa, Sharlane"
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- CFD analysis of multi-layer cooling channels in three-dimensionally structured grinding wheelsPublication . Costa, Sharlane; Capela, Paulina; Hassui, Amauri; Ribeiro, J.E.; Pereira, Mário; Soares, DelfimMinimizing heat damage and surface integrity loss in grinding depends on effective cooling. Conventional techniques, however, suffer with low efficiency because of the fast air barrier restricting fluid access. Grinding wheels with internal cooling channels have been suggested to solve this; nonetheless, the impact of channel geometry and multi-layer topologies is yet unknown. This work investigates their effects on coolant flow pattern and thermal performance by means of computational fluid dynamics (CFD) simulations, experimental validation, and statistical optimization combined. The ideal arrangement was found by the Taguchi- Grey study to be 30 channels, 78 degrees inclination, 1.7 mm diameter and 2 mm interlayer distance. ANOVA determined that diameter (59.7 %) and number of channels (21.8 %) are the most influential parameters. CFD results showed that multilayer structures significantly increase fluid dispersion in the workpiece. The three-layer design stood out for providing the most uniform and dynamic fluid distribution, reducing cooling inconsistencies. Grinding tests confirmed that this configuration achieved the lowest temperatures for all different depths of cut. These findings highlight that increasing the number of flutes alone is insufficient; a three-dimensional flute structure with optimized geometry is essential to ensure efficient cooling. By integrating numerical modeling, statistical optimization, and experimental validation, this study provides a framework for designing grinding wheels with internal cooling channels, improving fluid distribution and thermal control.
- CFD and experimental investigation of channel diameter effects in structured internally cooled grinding wheelsPublication . Costa, Sharlane; Capela, Paulina; Sousa, Maria; Hassui, Amauri; Ribeiro, J.E.; Pereira, Mário; Soares, DelfimEfficient cooling and lubrication are critical in grinding due to the high specific energy and limited contact area involved. Conventional external methods often fail to penetrate the air barrier formed by the rotating wheel, leading to excessive heat generation and reduced process stability. To overcome this limitation, this study investigates vitrified alumina grinding wheels with internal cooling channels designed for directed fluid delivery. Three structured configurations were developed, all with identical total outlet area (similar to 54 mm(2)) but different channel diameters (0.6, 1.0, and 1.5 mm), to isolate the effect of channel size on fluid flow and grinding behavior. Computational fluid dynamics (CFD) simulations were performed to assess outlet velocity and surface coverage, while grinding tests quantified tangential and normal forces, temperature variation (Delta T), force ratio (F-t/F-n), and specific grinding energy. Narrow channels provided uniform surface coverage but limited jet velocity due to higher hydraulic resistance, whereas wider channels enhanced outlet velocity at the expense of flow uniformity. The intermediate configuration (& Oslash; 1.0 mm) yielded the most balanced performance, achieving up to 38 % lower tangential force and 41 % lower temperature than the & Oslash; 0.6 mm design, while maintaining low specific energy across all depths of cut. Correlation between CFD and experimental results confirmed that both jet intensity and spatial distribution govern cooling and lubrication efficiency. These insights support the design of more efficient and sustainable grinding wheels through tailored channel geometries.
- Control of the dimensional variation adjusting the thermal drying cycle of abrasive composites with incorporated PLAPublication . Costa, Sharlane; Marques, F.D.P.; Pereira, Mário J.; Ribeiro, J.E.; Soares, DelfimIn composite production, during the thermal drying cycle (T<100ºC), size variation of the composite material occurs due to thermal expansion and water elimination. However, when incorporating PLA components, produced by additive manufacturing, into the abrasive composite, the dimensional variation of the set is very large due to the higher polymer thermal expansion. During this stage, this composite, still in the green state, could not have the sufficient mechanical strength to withstand dimensional variations. These can result in crack formation. Therefore, the proper thermal cycle is a critical step. To define the convenient heating rate during the drying of composites with a PLA piece, thermomechanical analyzes were conducted. Three different heating ramps were tested, 0.1, 0.5, and 2.0 ºC/min in the most critical phase of dimensional change (up to 60 ºC), after this temperature the heating continues at 2 ºC/min. The results indicate that the slower the heating rate, the higher the absorption of the polymer's expansion by the composite. In the slower heating rate (0.1 ºC/min) it was possible to minimize the dimensional variation of the samples by more than 94%.
- Coolant flow in structured grinding wheels: CFD validation via high-speed imaging and particle trackingPublication . Costa, Sharlane; Souza, Andrews; Neves, Lucas B.; Ribeiro, J.E.; Pereira, Mário; Soares, DelfimEfficient coolant delivery is essential in grinding to control heat generation, minimize tool wear, and preserve workpiece integrity. However, Computational Fluid Dynamics (CFD) models commonly used for coolant system design remain rarely validated due to the extreme speeds and complex multiphase flows involved. This work addresses this gap by combining CFD simulations with targeted experiments to evaluate heat removal effectiveness in internally cooled grinding wheels with three channel inclinations: positive, straight, and negative. Transparent resin prototypes enabled high-speed imaging and particle tracking for flow field validation, while grinding tests measured temperature rise and mechanical loads. Results demonstrate that channel inclination strongly affects fluid acceleration, jet coherence, and penetration into the grinding zone, with the positive inclination producing the highest outlet velocities and reducing temperature rise by up to 67%. Particle tracking confirmed CFD predictions within 16% deviation, validating the model’s reliability. By establishing a direct correlation between coolant jet dynamics, heat dissipation, and process performance, this study demonstrates a methodology for the thermal optimization of internal cooling systems in rotating tools. The approach provides a pathway for improving energy efficiency, extending tool life, and reducing coolant consumption in industrial machining processes.
- Estudo da qualidade micrográfica de juntas soldadas em ligas de alumínio pelo processo MIGPublication . Costa, Sharlane; Ribeiro, J.E.; Gonçalves, José; Medeiros, Bruno BelliniO objetivo desta dissertação de mestrado é o estudo da qualidade micrográfica de juntas soldadas em ligas de alumínio pelo processo MIG robotizado. O ciclo de tratamentos realizados foi constituído por solubilização, têmpera e envelhecimento artificial. Também foi definido um intervalo de espera entre os dois últimos tratamentos afim de avaliar o efeito de um possível envelhecimento natural. Para definição do quadro de variáveis recorreu-se a literatura e a trabalhos antigos, para a solubilização foram definidas 3 temperaturas: 480, 500 e 520ºC, e tempos de 30, 60 e 90 minutos. O intervalo de espera entre a têmpera e o envelhecimento foi de 0, 12 e 24 horas. E por último, as variáveis definidas para o tratamento de envelhecimento artificial foram temperaturas de 160, 175 e 190ºC, e tempos de 6, 14 e 20 horas. Utilizando o método das matrizes ortogonais de Taguchi, definiu-se que, para o número de parâmetros selecionados, seriam necessários 18 ensaios diferentes. Para realização do estudo foram soldadas chapas da liga AA6082-T6, através do processo MIG robotizado, a seguir foram cortadas as amostras e realizados os tratamentos térmicos. Na sequência as amostras, foram caracterizadas por microscopia ótica e por medição das microdurezas na junta soldada. Verificou-se que a temperatura de solubilização tem efeito sobre os valores de dureza, amostras solubilizadas a 520ºC indicam durezas cerca de 13% maiores quando comparadas as amostras que foram solubilizadas a 480ºC. Além disso, comparando a amostra que atingiu o maior valor de microdureza com uma amostra com ausência de tratamento térmico, constatou-se um aumento de 43% na dureza média da peça.
- Experimental and numerical study to minimize the residual stresses in welding of 6082-T6 aluminum alloyPublication . Costa, Sharlane; Souza, Maria Sabrina; Braz-César, Manuel; Gonçalves, José; Ribeiro, J.E.One of the most important negative consequence in the fusion welding processes is the generation of tensile residual stresses in welded joints. The main goals of this work are to determine the optimal combination of welding parameters to minimize the residual stress level and the influence of each welding parameter in that feature to weld 6082-T6 aluminum alloy plates using the GMAW welding process. To achieve these goals was implemented the Taguchi orthogonal array (L27) to define the design of numerical and experimental tests. All combinations were simulated in the Simufactwelding 6.0 software, from which it was possible to obtain the values of maximum residual stresses. The data treatment was carried out, reaching the combination of levels for each parameter. With ANOVA analysis was found that the parameter with the greatest influence in the residual stress generation was the welding speed, while the parameter with the least influence was the torch angle. Also, to minimize the residual stresses it was observed that the optimal combination of welding parameters is welding current intensity of 202 A, welding speed of 10 mm/s, and 30° of inclination of the angular torch. The two simulations that resulted in the highest and lowest residual stresses were validated experimentally by the hole drilling method to measure the residual stresses.
- Micrographic study of weded joints in aluminium allows by mig processPublication . Costa, Sharlane; Ribeiro, J.E.; Gonçalves, José; Medeiros, Bruno B.; Izeda, António Eduardo CruzThe objective of this work is to analyze and evaluate the influence of thermal treatments of solubilization, tempering and aging sequence, made in the 6082 - T6 alloy, previously welded by the MIG (Metal Inert Gas) welding process. In this work, a microscopically analysis of the welded and a thermally treated joint is realized, to evaluate the microstructure quality and the results found by varying the time and temperature during the treatment. In addition, it is intended to verify the influence of the waiting time amongst the heat treatment of quenching and artificial aging.
- A New Grinding Wheel Design with a 3D Internal Cooling Structure SystemPublication . Costa, Sharlane; Capela, Paulina; Souza, Maria S.; Gomes, José R.; Carvalho, Luís; Pereira, Mário J.; Soares, DelfimThis work discusses challenges in conventional grinding wheels: heat-induced tool wear and workpiece thermal damage. While textured abrasive wheels improve heat dissipation, the current surface-only methods, such as those based on laser and machining, have high renewal costs. The proposed manufacturing technology introduces an innovative 3D cooling channel structure throughout the wheel, enabling various channel geometries for specific abrasive wheel applications. The production steps were designed to accommodate the conventional pressing and sintering phases. During pressing, a 3D organic structure was included in the green body. A drying cycle eliminated all present fluids, and a sintering one burnt away the structure, revealing channels in the final product. Key parameters, such as binder type/content and heating rate, were optimized for reproducibility and scalability. Wear tests showed a huge efficiency increase (>100%) in performance and durability compared of this system to conventional wheels. Hexagonal channel structures decreased the wear rates by 64%, displaying superior wear resistance. Comprehensive CFD simulations evaluated the coolant flow through the cooling channels. This new design methodology for three-dimensionally structured grinding wheels innovates the operation configuration by delivering the coolant directly where it is needed. It allows for increasing the overall efficiency by optimizing cooling, reducing tool wear, and enhancing manufacturing precision. This 3D channel structure eliminates the need for reconditioning, thus lowering the operation costs.
- Performance of 3D-structured grinding wheels with multi-layer internal cooling channelsPublication . Costa, Sharlane; Capela, Paulina; Hassui, Amauri; Ribeiro, J.E.; Pereira, Mário; Soares, DelfimGrinding is a key machining process in industries that demand high precision and surface quality. However, the conventional flood cooling method is often ineffective due to the air barrier formed by the rotating wheel, which restricts fluid access to the contact zone. This causes thermal instability, high coolant use, and environmental impact. To overcome these limitations, this study investigates alumina grinding wheels with internal cooling systems, fabricated by a novel additive route. Sacrificial 3D-printed polymer inserts were embedded during pressing and eliminated during sintering, enabling multilayered channels within a monolithic abrasive matrix. This represents the first practical application, with detailed method of production, of a fully embedded cooling system in vitrified grinding wheels. Two configurations, with one and three internal channel layers, were compared to a conventional wheel under external cooling. Controlled grinding tests on AISI 1045 steel were performed at varying depths of cut, and key variables such as cutting forces, force ratio, specific energy, and temperature variation (Delta T) were analyzed. The three-layer wheel showed the best performance, reducing tangential force by up to 49.3 %, force ratio by 21.3 %, specific energy by 50 %, and Delta T by 58.6 % compared to the conventional system. A detailed thermal profile enabled segmentation into cut-in, steady-state, and cut-out zones. The greatest benefit from internal cooling occurred in the steady-state region, with heating rates reduced by up to 78 %. These results confirm that the proposed additive manufacturing approach offers a scalable route to produce structured wheels with embedded channels, improving coolant application, process stability, and sustainability in high-performance grinding.
- Solidification and heat-treatment conditions affecting the tensile properties and fracture feature of an automotive alsimg alloyPublication . Barbosa, Carolina; Azevedo, Hugo; Costa, Sharlane; Ribeiro, J.E.; Carlos, José; Costa, Tiago; Rocha, OtavioIn this work, a study on the interrelationship between the solidification and heat-treatment processes parameters with tensile properties and fracture feature was performed with an automotive AlSiMg alloy. For that, samples of the horizontally solidified Al7Si0.3 Mg (wt.%) alloy were subjected to the T6-heat treatment, and tensile tests were performed on both investigated samples, under conditions established from the literature. The solidification conditions such as growth and cooling rates and the secondary dendritic spacing (V-L and T-R and lambda(2), respectively) and their effects on the ultimate tensile strength (sigma(UTS)) and elongation (E%) were evaluated. Higher sigma(UTS) values were observed in the heat-treated samples and finer microstructures resulted in a better E% performance. Analysis by SEM/EDS fractography on both samples showed a mix between brittle and ductile fractures, constituted by cleavage facets, secondary cracks, facets covered with micro-voids, tear ridges and dimples. This allowed the deduction of the occurrence of a transition of a transition from ductile to brittle fracture along the solidified ingot as well as the predominance of brittle fracture in the heat-treated samples.