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  • ItemErrata
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    (2023-04-01) Silveira, Marcos Paulo Motta [UNESP]; Ramos, Nathália de Carvalho [UNESP]; Lopes, Guilherme da Rocha Scalzer [UNESP]; Tribst, João Paulo Mendes; Bottino, Marco Antonio [UNESP]; Universidade Estadual Paulista (UNESP); University of Taubaté (UNITAU); The University of Amsterdam and Vrije Universiteit
    Error in Figure In the original publication [1], there was a mistake in Figure 2 as published. “Aging” labels referring to “Yes” and “No” on the figure were switched. The corrected Figure 2 appears below. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.
  • ItemArtigo
    Aeroelastic energy harvesting in flutter condition increases with combined nonlinear stiffness and nonlinear piezoelectrical coupling
    (2023-02-01) Amaral, Ana Carolina Godoy [UNESP]; De Marqui, Carlos; Silveira, Marcos [UNESP]; Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP)
    The dynamic behaviour of an aeroelastic energy harvester using a piezoelectric transducer is studied. An important question in applications of energy harvesting is how to increase the efficiency of energy conversion. The study of both mechanical and electrical nonlinear terms has proven important in this context, both to provide more accurate models and to aid the design of purposely nonlinear systems. Here, the influence of plunge cubic nonlinear stiffness and nonlinear piezoelectrical coupling is investigated with respect to flutter speed, mechanical and electrical power. Different combinations of nonlinear terms are explored and compared to the linear case. The influence of the nonlinear coefficients and of the parameters of the electrical domain on the behaviour of the system are analysed analytically via the method of multiple scales (MMS) and numerically via a fourth-order Runge–Kutta method (RK). A Poincaré section method is proposed to determine the period of oscillations of the nonlinear systems at flutter. The results indicate that nonlinear stiffness has more influence in increasing flutter speed, and nonlinear piezoelectrical coupling has more influence in increasing electrical power. More energy is transferred from the pitch motion than from the plunge motion. Flutter speed, mechanical and electrical power increase with nonlinear stiffness, indicating that neglecting this characteristic can lead to underestimation of flutter speed and harvested energy.
  • ItemArtigo
    Application of MQL with cooled air and wheel cleaning jet for greener grinding process
    (2023-03-01) Daniel, Douglas Maiochi [UNESP]; Moraes, Douglas Lyra de [UNESP]; Garcia, Mateus Vinicius [UNESP]; Lopes, José Claudio [UNESP]; Rodriguez, Rafael Lemes [UNESP]; Ribeiro, Fernando Sabino Fonteque [UNESP]; Sanchez, Luiz Eduardo de Angelo [UNESP]; Bianchi, Eduardo Carlos [UNESP]; Universidade Estadual Paulista (UNESP)
    Metalworking fluids (MWF) or flooded process based on mineral oil are widely used in industry, which is unsustainable and causes damage to employees and the environment, in addition to making up a significant part of the machining cost. On the other hand, abrasive machining methods, such as grinding, are increasingly used for their excellent finish and geometric precision but use large quantities of metalworking fluids. This work evaluates the alternative methods Minimum Lubricant Quantity (MQL), MQL + Cooled Air (CA), MQL + Wheel Cleaning Jet (WCJ), and MQL + Cooled WCJ in the grinding of AISI 4340 steel compared to the application of flooded process. Surface roughness, roundness error, G ratio, grinding power, specific energy, microhardness, cost per piece, and carbon emission tests were applied. From the results, MQL reduced the cost of grinding around 90% and carbon emission by 67% compared to grinding with flooded process. The MQL + CWCJ produced the best results of surface quality compared to other alternative techniques, significantly approaching the results of the flooded process.
  • ItemArtigo
    Dynamic analysis of an electromagnetic vibration absorber in a non-ideal system
    (2023-01-01) Petrocino, Eduardo Abuhamad [UNESP]; Balthazar, José Manoel [UNESP]; Tusset, Ângelo Marcelo; Gonçalves, Paulo José Paupitz [UNESP]; Silveira, Marcos [UNESP]; Universidade Estadual Paulista (UNESP); Federal University of Technology – Paraná
    A dynamic system usually used in engineering are rotating machines fixed to flexible structures, and an excessive vibration known as the Sommerfeld effect may occur in the passage of the resonance. This research aims to analyze an electromagnetic absorber in a non-ideal system, a simple model for the analysis of the first mode of a beam. In this context, an investigation of the dynamic behavior of a cantilever beam with a dc motor coupled to its free end, having an unbalanced mass on its axis, providing a non-ideal energy source. A permanent magnet is attached to this same free end, which is immersed inside a coil attached to the base. In this step, an analysis of the dynamic behavior is carried out by means of an analytical solution approximated by the averaging method and by numerical computational simulations. The absorber reduces the phenomena caused by the Sommerfeld effect and reduces the region of instability.
  • ItemTrabalho apresentado em evento
    Strain Energy Approach for Nonlinear Stiffness Coeffcients in the Design of Periodic Structures
    (2023-01-01) Cruz, Rodrigo dos Santos [UNESP]; Silveira, Marcos [UNESP]; Universidade Estadual Paulista (UNESP)
    In this work, we explore the dynamic behaviour of a discrete model of a periodic structure under harmonic input with nonlinear stiffness. The periodic structure has a unit cell with three degrees of freedom. We devise an approach that replaces the linear stiffness characteristic of the structure with a nonlinear one in which the nonlinear stiffness coefficients provide the same strain energy. The effect of this approach on the frequency response is analysed using numerical simulation, focusing on band gaps. The approach to determining nonlinear stiffness coefficients is based on the concept of equivalent elastic strain energy. This is different from the common approach found in the literature of adding a cubic term to the linear one, resulting in an increase in the elastic deformation energy of the system. Once the strain energy of the linear system is determined, a family of possible nonlinear stiffness coefficients is found, parameterised by the ratio between the linear and cubic coefficients. This approach can be used with hardening or softening stiffness characteristics. With the nonlinear stiffness coefficients defined, the dynamic response of the metastructure shows the usual shift to high and low frequencies. In addition, some frequency ranges are shown where vibration levels can be greatly reduced when the ratio of nonlinear stiffness coefficients is increased, compared to the case where there are only linear springs. Also, it is shown that the addition of the nonlinear component in the structure can increase or decrease the distance between the resonant frequencies.
  • ItemArtigo
    Bond Strength between Different Zirconia-Based Ceramics and Resin Cement before and after Aging
    (2022-10-01) Silveira, Marcos Paulo Motta [UNESP]; Ramos, Nathália de Carvalho [UNESP]; Lopes, Guilherme da Rocha Scalzer [UNESP]; Tribst, João Paulo Mendes; Bottino, Marco Antonio [UNESP]; Universidade Estadual Paulista (UNESP); University of Taubaté (UNITAU); The University of Amsterdam and Vrije Universiteit
    The objective of this study was to evaluate the bond strength of different stabilized zirconias with resin cement and evaluate the susceptibility to thermal aging of the adhesive interface. Zirconia discs (Vita Zahnfabrik, Bad Säckingen, Germany) were obtained: 3Y-TZP first generation (translucent), 3Y-TZP third generation (high-translucent), 4Y-PSZ (super-translucent), and 5Y-PSZ (extra-translucent). Each disc had its surface polished with a standardized protocol. The specimens were cleaned and sintered according to the manufacturer’s recommendation (conventionally: ~12 h). However, 3Y-TZP groups were subdivided into subgroups and sintered following the speed sintering process (~80 min). After their sintering shrinkage, the dimensions of the final discs were 12 mm × 2 mm. The specimens were blasted with 50 μm aluminum oxide (1 cm distance, 2 bar pressure, and 2 s/cm²), cleaned, and silanized with an MDP primer. After the surface treatment, a resin cement cylinder was built on the ceramic surface (Ø = 1 mm; h = 2 mm). Half of the specimens of each group were subjected to a microshear bond strength test in a universal testing machine after 24 h of cementation, while the other half were subjected to thermocycling prior to the bond strength test (6000 cycles; 5 °C–55 °C, 30 s for each bath). Bond strength data were submitted to two-way ANOVA and Tukey’s test (95%), as well as Weibull analysis, to determine adhesive reliability. Bond strength was statistically different among the materials, and only 3Y-TZP third generation and 4Y-PSZ were not affected by thermal aging. The speed sintering method was statistically similar to the conventional process for 3Y-TZP first generation. However, 3Y-TZP third generation showed higher immediate bond strength when speed sintered. The Weibull modulus was superior for conventional 3Y-TZP third generation and 4Y-PSZ. In this study, thermal aging caused a degradation of the adhesive interfaces of 3Y-TZP first generation and 5Y-PSZ with the resin cement; however, it did not affect the interfaces of 3Y-TZP third generation and 4Y-PSZ. The speed sintering method did not affect the long-term bond strength with the resin cement. Adhesive reliability was superior for 3Y-TZP third generation and 4Y-PSZ.
  • ItemArtigo
    ZrO2-CNT composite production through reducing atmosphere
    (2022-10-01) Neto, Vicente Gerlin; Pereira, Cristian Guilherme Barbosa [UNESP]; Faglioni, Felipe Dias [UNESP]; Fortulan, Carlos Alberto; Foschini, Cesar Renato [UNESP]; Science and Technology of São Paulo – IFSP; Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP)
    Zirconia (ZrO2) is a well-known and widely used ceramic in engineering applications and is even termed as ‘ceramic steel’ in its tetragonal stabilised phase (TZP). However, even the tetragonal zirconia has some issues with low fracture toughness and attempts to enhance its toughness have been researched thoroughly. A recent and promising toughening method is the addition of other components to the TZP ceramic matrix. Different additives are used with nanocomponents as a major means of zirconia toughening, using advanced sintering and processing techniques such as flash sintering and spark plasma sintering. This work aims to produce a composite with zirconia matrix adding nanocomponents (carbon nanotubes) to modify and analyse the composite properties, using common methods of processing and sintering. With said common methods (furnace sintering and hydrothermal mixing), we produced ZrO2-CNT composites with 1.0 and 2.0% in weight of CNTs and analysed the nanotubes’ presence and their influence on the composite properties after sintering. The composite showed good results, with CNTs’ integrity achieved in the composites, as observed by scanning electron microscopy. Composite density was as high as 96% with 1.0 wt% of CNTs and, for mechanical properties, hardness suffered a little loss in the composites when compared to the pure zirconia.
  • ItemArtigo
    Advanced ceramic grinding process combined to hazard mitigation to the employees’ health by using an alternative lubri-refrigeration technique
    (2023-01-01) Fernandes, Lucas de Martini [UNESP]; Javaroni, Rafael Liberatti [UNESP]; Rodrigues, Matheus de Souza [UNESP]; Ávila, Benício Nacif [UNESP]; Moraes, Douglas Lyra de [UNESP]; Ribeiro, Fernando Sabino Fonteque; Rodrigues, Alessandro Roger; França, Thiago Valle [UNESP]; Sanchez, Luiz Eduardo de Angelo [UNESP]; Bianchi, Eduardo Carlos [UNESP]; Lopes, José Claudio [UNESP]; Universidade Estadual Paulista (UNESP); Science and Technology of Paraná; Universidade de São Paulo (USP)
    The sustainable industry is becoming a global trend that aims to align productivity, quality, and environmental preservation. In the grinding process, the need arises to develop new technologies to replace cutting fluids, which are highly toxic substances. The minimum quantity of lubrication (MQL) technique is alternative lubrication and cooling method that makes machining more ecological. However, its application is still tiny due to its low cooling power and cleaning of the workpiece-tool interface. On the other hand, the grinding conditions improve when associated with the wheel cleaning jet (WCJ) system, which consists of applying an inclined compressed air jet on the grinding wheel, avoiding clogging and the adhesion of chips on the surface of the grinding wheel. From this perspective, this work aims to perform a comparative analysis between the flood method and the MQL and MQL + WCJ techniques, in the external cylindrical grinding of alumina ceramic (Al2O3), at feed rates of 0.25, 0.50, and 0.75 mm/min. The output parameters analyzed will be diametrical wheel wear, G-ratio, surface roughness, roundness error, grinding power, cost, and pollution analysis. The G-ratio was 40% better using MQL + WCJ compared to MQL, while the grinding cost per piece with MQL + WCJ represented about 24% of the price of the conventional method. The results show that the association of WCJ to MQL improves the efficiency of the MQL technique, guaranteeing good results and being an eco-friendly technique.
  • ItemArtigo
    Analysis of the Inconel 718 properties after roller burnishing
    (2022-01-01) Casarin, Samuel José [UNESP]; de Godoi, Eduardo Luiz; de Angelo Sanchez, Luiz Eduardo [UNESP]; de Alcântara, Anne Caroline Melo [UNESP]; Gonçalves, Aparecido Carlos [UNESP]; Universidade Estadual Paulista (UNESP); Estrada Municipal Paulo Eduardo de Almeida Prado
    Experimental studies were performed to investigate the influence of roller burnishing (RB) parameters, as the temperature and the number of RB operations, on the subsurface microstructures and microhardness, surface roughness and roundness deviation of the Inconel 718 alloy. The experimental results indicate that the RB enhance the surface quality, reduces the surface roughness by 76.7% and increase the microhardness by 20.9% compared to the turned part. RB affects the microstructural morphology of the subsurface grains and improves roundness deviation of Inconel 718 parts. The presence of precipitates in the plastic deformation zone contributes to increase the mechanical strength of the subsurface. The RB operation, both at room temperature and at 310°C, proved to be very efficient in reducing the surface roughness of the Inconel 718. About roundness deviation, the increase of the RB temperature induces a greater specimen roundness deviation, and the hot RB operation is not favourable to improve the circularity of the specimen.
  • ItemArtigo
    Evaluating the optimized lubri-cooling technique for various cutting conditions in through-feed centerless grinding process
    (2023-04-01) Neto, Luiz Maurício Gonçalves; Rodriguez, Rafael Lemes [UNESP]; Lopes, José Claudio [UNESP]; Ribeiro, Fernando Sabino Fonteque [UNESP]; de Moraes, Douglas Lyra [UNESP]; de Angelo Sanchez, Luiz Eduardo [UNESP]; de Mello, Hamilton José [UNESP]; Bianchi, Eduardo Carlos [UNESP]; Schaeffler Technologies AG & Co. Herzogenaurach; Universidade Estadual Paulista (UNESP)
    The centerless grinding process is a fast and efficient process for precision batch and mass production grinding. This process employs wide wheels which allow substantial removal rates, and another additional advantage is that centers are not required as in center grinding. Wide wheels yield to lower wheel wear and higher accuracy for long periods, particularly when using in-process gauging. Many materials and parts of various shapes and sizes are produced by the centerless grinding, in particular, for bearing and automotive industries. In grinding process, the application of metal working fluid (MWF) in order to avoid thermal damages and excessive form deviation are indispensable. In this regard, this work aims to contribute to optimization of machining process through-feed by the study of centerless grinding process under the application of the optimized lubri-cooling technique by a novel multitubular nozzle for various cutting conditions. The multitubular nozzle was employed with emulsion (ME) and compressed air simultaneously (ME + CA) and with conventional nozzle (CN) application for a stock material removal (SMR) of 0.10 and 0.03 mm. All techniques were tested for three different flow rates: 10, 20, and 40 L/min. Surface roughness of the ground surface, roundness deviation, and SEM images of roundness deviation were analyzed. As a result, the ME + CA optimized application produced lower results than CN nozzles in general and the increase of surface roughness values is also produced by higher feed rate values which results in thicker chips in grinding process.
  • ItemArtigo
    Sustainable thinking toward to industry's future combined with new knowledge on greenhouse effect mitigation generated by the grinding process
    (2023-02-01) Lopes, José Claudio [UNESP]; Carvalho, Guilherme Antonio de [UNESP]; Moretti, Guilherme Bressan [UNESP]; Ávila, Benício Nacif [UNESP]; Rodrigues, Matheus de Souza [UNESP]; Garcia, Mateus Vinícius [UNESP]; Ribeiro, Fernando Sabino Fonteque; Rodrigues, Alessandro Roger; Sanchez, Luiz Eduardo de Angelo [UNESP]; Bianchi, Eduardo Carlos [UNESP]; Universidade Estadual Paulista (UNESP); Jacarezinho Campus; Universidade de São Paulo (USP)
    Grinding is a machining process applied in the manufacture of components that require an excellent surface finish and high geometric and dimensional precision, being applied in the final stages of component manufacturing. Due to its high heat generation, grinding needs adequate lubrication and cooling methods, aiming to meet the demands of the ground component as well as to mitigate the environmental impacts resulting from the application of cutting fluids. Allied with this, the growing demand for new materials, such as advanced ceramics, has become a new challenge for grinding. In addition to being chemically and thermally stable, advanced ceramics are highly resistant to wear, making grinding this type of material difficult. Traditionally, cutting fluids have alkanolamines, nitrosamines, volatile organic compounds, mineral oils, hydrocarbons and heavy metals in their composition. Thus requiring proper disposal to inhibit groundwater and soil contamination, reducing immediate and long-term damage to the planet and society. That said, it is extremely important that scientific and technological advances in machining processes, especially grinding, allow for cleaner machining through techniques that reduce the need to apply large volumes of cutting fluid. In this sense, the minimum quantity lubrication technique (MQL) consists of applying a small amount of oil through a jet of compressed air, achieving results similar to the flood method in many cases. However, the lower cooling capacity of MQL is an obstacle to overcome. Thus, this work analyzed advanced grinding ceramics using a diamond grinding wheel combined with a new technology responsible for cleaning the grinding wheel (WCJ) under four different angles (0°, 30°, 60° and 90°). Surface roughness, roundness error, diametral wear of the grinding wheel, G ratio, grinding power, grinding cost analysis, and pollutant CO2 emissions involving each application were evaluated. As a result, the flood lubri-refrigeration method showed the best performance in roughness and surface roundness error values. However, the MQL + WCJ 30° presented similar results about the flooding method, proving competitive for industrial use. Furthermore, MQL applications led to lower CO2 pollution values than the flood method, making it a great green alternative for the environment.
  • ItemArtigo
    Time-Domain Analysis of Acoustic Emission Signals during the First Layer Manufacturing in FFF Process †
    (2022-01-01) Lopes, Thiago Glissoi [UNESP]; Aguiar, Paulo Roberto [UNESP]; França, Thiago Valle [UNESP]; Conceição Júnior, Pedro de Oliveira; Soares Junior, Cristiano [UNESP]; Antonio, Zaqueu Ricardo Fernando [UNESP]; Universidade Estadual Paulista (UNESP); Universidade de São Paulo (USP)
    Additive manufacturing (AM) has been playing a crucial role in the fourth industrial revolution. Sensor-based monitoring technologies are essential for detecting defects and providing feedback for process control. Acoustic emission (AE) sensors have been used for a long time in a wide range of processes and fields, but they are still a challenge in AM processes. This work presents a study on the AE signals in the time-domain—raw and root mean square (RMS) values—regarding their behavior during the manufacture of a single-layer part in the fused filament fabrication process for two infill patterns. The tests were conducted on a cartesian 3D printer using polylactic acid material. The AE sensor was attached to the printer table through a magnetic coupling, and the signal was collected by an oscilloscope at 1 MHz sampling frequency. It was found that the raw AE signals behaved quite differently not just for the two infill patterns, but within the same pattern. The raw and RMS AE signals contained many spikes along the whole process, but the higher ones were those generally occurring at the end and/or start of a fabrication line. The RMS values, however, were useful for finding the start and end times of each fabricated line for both patterns. The mean RMS values showed nearly constant but distinct averages for the extruder-only, table-only and extruder–table movements.
  • ItemArtigo
    Eco-friendly thinking toward mitigating the greenhouse effect applied to the alumina grinding process
    (2023-02-01) Domingues, Bruno Biondo [UNESP]; Rodriguez, Rafael Lemes [UNESP]; Souza, Guilherme Guerra de [UNESP]; Ávila, Benício Nacif [UNESP]; Rodrigues, Matheus de Souza [UNESP]; Ribeiro, Fernando Sabino Fonteque; Rodrigues, Alessandro Roger; Sanchez, Luiz Eduardo de Angelo [UNESP]; Bianchi, Eduardo Carlos [UNESP]; Lopes, José Claudio [UNESP]; Universidade Estadual Paulista (UNESP); Science and Technology of Paraná; Universidade de São Paulo (USP)
    The grinding process manufactures parts with geometric and dimensional precision and surface finish. During the procedure, material removal requires high energy and generates heat in the cutting zone. The grinding of advanced ceramics, such as alumina (Al2O3, 97% purity), is even more complex and economically expensive due to its mechanical properties. Thus, cooling and lubrication techniques are needed to control temperatures. The conventional flood technique is currently the most used, but it has a high environmental impact combined with unhealthy chemical agents in the cutting fluid. As a result, cutting fluids are the inputs that pose the most significant risks and damage to the environment and human health. Applying atomized and pressurized cutting fluid directly to the cutting zone has shown manufacturing potential compared to the conventional flood technique to solve these problems. Despite this, the minimum quantity of lubricant (MQL) technique does not provide good thermal dissipation compared to traditional methods, requiring the inclusion of auxiliary systems. In addition, one of these techniques deals with adding different proportions of water to the mixture, aiming to improve the heat transfer of the process and minimize the phenomenon of clogging the surface of the grinding wheel. Thus, this study analyzed the performance of a diamond grinding wheel in the advanced process of ceramic grinding using different proportions of cutting fluid applied to the MQL system, as follows: MQL + Pure (Pure—100% cutting fluid), MQL + 50% (50% cutting fluid and 50% water), MQL + 25% (25% cutting fluid and 75% water), and MQL + 15% (15% cutting fluid and 85% water) compared to the flood technique. Thus, surface roughness, soil surface topography by confocal microscopy analysis, roundness error, diametral grinding wheel wear, G-ratio, grinding cost analyses, and CO2 pollution analyses were evaluated. In addition, MQL applications revealed fewer pollutants. Furthermore, they were more economical application conditions from the grinding cost analysis, making them a great eco-friendly alternative for use in the industrial sector.
  • ItemTrabalho apresentado em evento
    On the Pipe Localization Based on the Unwrapped Phase of Ground Surface Vibration Between a Roving Pair of Sensors
    (2023-01-01) Iwanaga, Mauricio Kiotsune [UNESP]; Brennan, Michael John [UNESP]; Scussel, Oscar; de Almeida, Fabrício César Lobato [UNESP]; Karimi, Mahmoud; Universidade Estadual Paulista (UNESP); University of Southampton; University of Technology Sydney
    Buried pipes are used worldwide to transport water. Although they are convenient, a large amount of water is wasted during the transportation. To minimize such a problem, water companies apply different technologies to locate leaks in their pipe networks, where the buried pipe is usually located first. Electromagnetic techniques can be used to locate buried pipes, but their performance is limited by the moisture content of the surrounding soil. Active vibro-acoustic techniques have also been investigated to locate buried pipes, in which vibro-acoustic energy is introduced into the soil by an excitation source. Although they are promising, their practical application can be expensive and complex due to the setup of an excitation mechanism. The aim of this paper is to present a passive vibro-acoustic localization technique for buried water pipes, in which a leak is the source of excitation. The localization technique is based on the calculation of an approximate slope for the unwrapped phase between a pair of sensors placed on the ground surface. The performance of the two-sensor technique is tested with two datasets, one extracted from a numerical model of the buried pipe system and the other extracted from an experiment carried out on a test rig. The results highlight the potential of the two-sensor technique in locating buried water pipes.
  • ItemTrabalho apresentado em evento
    An Investigation into the Factors Affecting the Bandwidth of Measured Leak Noise in Buried Plastic Water Pipes
    (2023-01-01) Scussel, Oscar; Brennan, Michael J. [UNESP]; de Almeida, Fabricio C. L. [UNESP]; Iwanaga, Mauricio K. [UNESP]; Muggleton, Jennifer M.; Joseph, Phillip F.; Gao, Yan; University of Southampton; Universidade Estadual Paulista (UNESP); Chinese Academy of Sciences
    Inspection and preservation of buried water pipelines is of importance in the modern world. The wastage of water due to leaks is a global problem and existing technologies/methods to detect leaks in buried pipelines still face challenges, such as how to predict the bandwidth of measured leak noise using acoustic correlators, and what are the main factors affecting this frequency range. The leak noise bandwidth is useful information for operators to know before carrying out tests in the field, and currently there is no practical way of predicting this frequency range. This paper presents an approach to predict the bandwidth and investigates the main factors affecting it such as the distance between the sensors, wave speed and attenuation of the fluid-dominated wave, which is the main carrier of leak noise. To achieve this, a water-pipe-soil-sensor model is represented in terms of filters, allowing an investigation into the corresponding physical/geometric characteristics that affect the bandwidth of the measured leak noise. It is shown that the dominant factors are the material and geometry of the pipe, the properties of the surrounding soil and the type of transducer used.
  • ItemArtigo
    Green manufacturing concept applied to the grinding process of advanced ceramics using an alternative lubri-refrigeration technique
    (2022-12-01) Talon, Anthony Gaspar [UNESP]; Sato, Bruno Kenta [UNESP]; Rodrigues, Matheus de Souza [UNESP]; Ávila, Benício Nacif [UNESP]; Cuesta, Jorge Luiz [UNESP]; Ribeiro, Fernando Sabino Fonteque; Rodrigues, Alessandro Roger; Sanchez, Luiz Eduardo de Angelo [UNESP]; Bianchi, Eduardo Carlos [UNESP]; Lopes, José Claudio [UNESP]; Universidade Estadual Paulista (UNESP); Science and Technology of Paraná; Universidade de São Paulo (USP)
    The growing demand for current and future projects lacks materials development and their manufacturing process, mainly when they need to be used in inert applications, where no physical or chemical reaction can interact with the elements around them. In this context, ceramic materials have stood out in applications that demand high resistance to temperature and wear, such as engine components and in situations where greater stability and chemical compatibility are required, such as prostheses and medical components. However, the manufacture of ceramic components is expensive and slow, given that the traditional manufacturing procedure for ceramic components is based on sintering. This process limits productivity and does not provide the final component with the high dimensional and shape quality required in more specific applications. However, there is still a lack of studies on the large-scale manufacturing processes of these products, mainly related to their grinding. Therefore, it is crucial to study the best ways of processing materials that will soon be essential to the mechanical, electronic, and biological industries. Furthermore, studies about advanced ceramics have become increasingly indispensable, based on factors such as high added values due to the difficulty of manufacturing combined with the high environmental impact caused by this process. However, advanced ceramics are materials with difficult to machine because of their high hardness and fragility properties, becoming required manufacturing processes more complex, such as grinding. Therefore, this paper explored several conditions applied to advanced ceramic, approaching the main variables used by worldwide industries, being: surface roughness (Ra), roundness error, diametral wheel wear, G-ratio, grinding power, and analysis costs process. The grinding process used in the research was of kind plunge combined with a diamond wheel applied to four different feed rates: 0.25, 0.50, 0.75, and 1.00 mm/min, in which two systems by application of cutting fluid in the process were also used: flood and MQL lubri-refrigeration techniques, with a flow rate of 15 l/min and 100 ml/h, respectively. The results indicated that the final conditions were affected by the increase in feed rate for both situations. Nonetheless, they were superior to those when the flood technique was used. However, the cost analysis process indicated that the drastic reduction of the amount of cutting fluid applied by the MQL provides better economic conditions when compared to the flood application technique, becoming this technique viable for industry application.
  • ItemArtigo
    Nonlinear numerical analysis and averaging method applied atomic force microscopy with viscoelastic term
    (2022-12-01) Ribeiro, Mauricio A.; Kurina, Galina A.; Tusset, Angelo M.; Balthazar, Jose M. [UNESP]; Universidade Tecnológica Federal do Paraná; Universidade Estadual Paulista (UNESP); Computer Science and Central of Russian Academy of Science
    We investigated the nonlinear behavior of an atomic force microscopy system with the contribution of the medium viscoelasticity term. Atomic force microscopy is one of the most used techniques for analyzing the surface topology of samples of interest. We propose a mathematical model for the nonlinear dynamics of the probe and we also assign a term that describes the viscoelasticity of the medium in which the probe is inserted. For our numerical analysis of nonlinear dynamics, we used the Lyapunov Exponent, Bifurcation Diagram, phase maps and Poincaré maps. We also determine a solution for a set of parameters using perturbation theory. In this paper, it is also shown that using higher approximations of averaging method, which allows to solve systems of differential equations with slowly changing variables instead systems with fast change of variables, is very effective to study dynamics of an atomic force microscopy.
  • ItemArtigo
    Optimization of Ceramics Grinding
    (Intech Europe, 2011-01-01) Bianchi, Eduardo Carlos [UNESP]; Aguiar, Paulo Roberto de [UNESP]; Diniz, Anselmo Eduardo; Canarim, Rubens Chinali [UNESP]; Sikalidis, C.; Universidade Estadual Paulista (UNESP); Universidade Estadual de Campinas (UNICAMP)
  • ItemArtigo
    Application of Minimum Quantity Lubrication in Grinding
    (Iste Ltd, 2010-01-01) Bianchi, Eduardo Carlos [UNESP]; Aguiar, Paulo Roberto de [UNESP]; Silva, Leonardo Roberto da; Canarim, Rubens Chinali [UNESP]; Davim, J. P.; Universidade Estadual Paulista (UNESP); CEFET
    This chapter deals with the application of minimum quantity lubrication (MQL) in grinding. This work aims to present some previous research results of the application of MQL in grinding by considering material to be ground (steels or ceramics) and type of grinding (surface, internal, and external cylindrical grinding).
  • ItemArtigo
    An experimental and numerical investigation of absorber positioning in a natural convection solar drying system
    (2022-09-01) Predolin, Rodrigo Eduardo [UNESP]; Ito, Mario Cesar [UNESP]; Palma, Geraldo Luiz [UNESP]; Scalon, Vicente Luiz [UNESP]; Universidade Estadual Paulista (UNESP)
    The known advantages of drying food are long term preservation, weight reduction and, consequently, minimizing the transportation and storage costs. Drying technology can also spoil the conditions for microbial growth. In this study, an indirect solar dryer with natural convection was developed, constructed and experimentally investigated for using in remote regions. It comprises three main parts: an absorber plate with 0.5 m2 surface area, a dryer chamber and an exhaust duct. The absorber plate position can be modified in this device and change the airflow conditions from over the upper face only to the upper and lower face (double passage). Tests changing this position increased the product humidity removal rate from 0.47 g/min to 0.56 g/min, the total water removal over the day from 185 g to 220 g and the average daily thermal efficiency from 8.5% to 19.8%. The equipment performance evaluation was possible due to the presence of temperature, humidity and atmospheric pressure sensors positioned at the air inlet and outlet. A turbine-type anemometer at the air outlet was used for airflow measurements. The other three temperature sensors placed on the absorber plate and a load cell located in the drying chamber are also used. The evaporation process was recorded based on load cells installed in the drying chamber. Another model was also applied to calculate the same parameter using the mass balance. A CFD model was build to compare with the experimental results and good agreement was found. Comparison for different solar dryer setups show a better efficiency when the absorber plate is positioned in the middle of the inlet flow.