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Search Results: 1 - 10 of 304640 matches for " G.F. Batalha "
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Mechanical behaviour characterizing and simulation of polyacrylate rubber
D. dos Santos,G.F. Batalha
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: of this paper is to investigate the influence of EB radiation on the mechanical behaviour of UV curing polyacrylate rubber (ACM) and to simulate its behaviour.Design/methodology/approach: The material was irradiated by two different EB doses, 100 kGy and 250 kGy, its mechanical behaviour was investigated with the help of uniaxial, equibiaxial and planar shear experiments. The results were applied to the Ogden’s Model (1972) in order to obtain the parameters to simulate the material behaviour by finite element method (FEM) and to compare experimental and FEM curves. The structure molecular changes caused by EB were investigated with the help of infrared spectroscopy.Findings: In most cases the experimental results showed an increase in the strength at rupture and a decrease in the elongation at the rupture with increasing of radiation dose. Equibiaxial and planar shear tests presented similar behaviour like uniaxial results, in terms of elongation decrease and strength increase, with some deviations. Ogden’s Model third order provided simulated curves with similar behaviour in comparison to experimental curves. The infrared spectroscopy showed different chemical group contents in the analyzed regions, surface and middle region.Research limitations/implications: Two doses of EB radiation were applied; higher or lower doses were not investigated.Practical implications: Improved behaviour of UV curing ACM can extend the range of industrial applications, or improve its performance in known applications.Originality/value: Usually EB radiation has been used to modify polymeric structure and to improve thermal and mechanical polymers behaviour. Regarding like rubber materials EB is usually applied as an alternative form of vulcanization. UV is a new type of curing for polyacrylate rubbers, which are usually cured by thermal processes.
Surface integrity functional analysis in hard turning AISI 8620 case hardened steel through 3D topographical measurement
A. Farias,S. Delijaicov,G.F. Batalha
Archives of Materials Science and Engineering , 2010,
Abstract: Purpose: This work aims investigate the resulting machined surface condition from hard turning process of mechanical components manufactured from case hardened steel.Design/methodology/approach: The surface was examined by parameters obtained from the three-dimensional surface topography obtained with an interferometric laser instrument.Findings: The selected roughness parameters analysis intends to have a functional characterization such as bearing capacity, fluid and lubricants retention ability and contact wear resistance.Research limitations/implications: The obtained results were validated against similar ones, showing that the employed measuring techniques and analyses were correctly conducted.Practical implications: The functional bearing area curve analysis parameters indicates that the resulting surface has a good area contact, good bearing capacity and reasonable ability to fluid retention as the reduced valley depth parameter Svk not produced higher values for all conditions tested.Originality/value: The obtained results in the surface roughness measurement shows consistency with other authors results, and it shows that the technique of hardened material turning is capable of producing surfaces with functionality and quality.
Improved model to predict machined surface roughness based on the cutting vibrations signal during hard turning
S. Delijaicov,F. Leonardi,E.C. Bordinassi,G.F. Batalha
Archives of Materials Science and Engineering , 2010,
Abstract: Purpose: The objective was to study the influence of cutting vibrations in hard turning of AISI 1045 steel.Design/methodology/approach: A design of experiments using a complete factorial was used in the experiments. The specimens were tempered and quenched with 53 HRC. A piezoelectric dynamometer for turning with an acquisition data system was used in the measurements.Findings: The results showed excellent correlation between the model and results and showed that the frequency amplitudes increase the model reliability by 5%.Research limitations/implications: The instrumentation of machine and its correlation with the amplitudes of frequencies from data system acquisition could personalize the models for each experiment on the machines.Originality/value: The paper uses a commercial piece and provides important information for the improvements in the roughness of hardened steel, which is an important factor for the components surface integrity.
Integrated product and process system with continuous improvement in the auto parts industry
I.B. Silva,G.F. Batalha,M. Stipkovik Filho,F.Z. Ceccarelli
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: Quality systems (QS) update must be based on the enterprise organization to assure customer satisfaction, as Deming, Juran and Feigenbaum did in their time, to seek improvement processes to reach high quality performance. This way, the proposal of this paper is the development of quality system integration model of product and process with continuous improvement.Design/methodology/approach: To reach this goal, a Brazilian automotive parts quality system was improved through the Computer Integrated Manufacturing (CIM), Design for Manufacturing and Assembly (DFMA) and Lean Six Sigma (LSS) methodologies.Findings: The paper shows what the problems are during the factory quality system management. The results achieved in the studied company show the performance quality evolution through their indicators.Research limitations/implications: The article presents quality system problems of only one Brazilian plant of an automotive industry.Practical implications: Presented in this article should be a way to look for continuous improvement methods.Originality/value: The paper is supported on the authors’ practical experiences to improve the quality system at a Brazilian plant.
Superficial integrity analysis in a super duplex stainless steel after turning
E.C. Bordinassi,M.F . Stipkovic,G.F. Batalha,S. Delijaicov
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: Purpose of this paper was to study the main effects of the turning in the superficial integrity of theduplex stainless steel ASTM A890-Gr6A.Design/methodology/approach: The focus of the work was the finishing operations and a complete factorialplanning was used, with 2 levels and 5 factors. The tests were conducted on a turning center with carbidetools and the main entrances variables were: tool material class, feed rate, cutting depth, cutting speed andcutting fluid utilization. The answers analyzed were: micro structural analysis by optical microscopy and x-raydiffraction, cutting forces measurements by a piezoelectric dynamometer, surface roughness, residual stress byx-ray diffraction technique and the micro-hardness measurements.Findings: The results do not showed any changes in the micro structural of the material, even when the greatercutting parameters were used. All the other answers were correlated with the cutting parameters and its bettercombination was founded for the best superficial integrity. The smaller feed rate (0.1 mm/v), smaller cuttingspeed (110 m/min) and the greater cutting depth (0.5 mm) provided the smaller values for the tensile residualstress, the smaller surface roughness and the greater micro-hardness.Research limitations/implications: The correlation between all the answers was very difficult to analyzebecause there was great interaction between the factors, but for some data group it was possible.Originality/value: The paper contribute for the study of the super duplex stainless steel, considering that no oneresearches was founded for the studied topics in this material in witch presents different behavior in machiningwhen compared with another stainless steels.
Mechanical and physical properties investigation of polyurethane material obtained from renewable natural source
D.J. dos Santos,L.B. Tavares,G.F. Batalha
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: The purpose of this paper is to investigate the influence of different polyol/diisocyanate ratios on the mechanical and physical behaviours of polyurethane based polymers.Design/methodology/approach: Castor oil was mixed, as polyol, to diisocyanate in order to obtain polyurethane based polymers. Besides the ideal stoichiometry, polyol/ diisiocyanate ratio, ratios with excess/lack of diisocyanates were provided. The mechanical behaviour was investigated by uniaxial tests. Differential Scanning Calorimetry (DSC) and Thermo gravimetric Analysis (TGA) were used to investigate the thermal behaviour. The various polymeric structures, obtained by the different ratios, were analysed and compared by Infrared Spectroscopy (IR).Findings: Mechanical performance was increased proportionally to contend of diisocyanate. High levels of diisocyanate have generated elongation decreasing and CO2 formation during curing, damaging mechanical behaviour due to bubble presence. Analytical experiments have showed important changes on: polymeric structures, glass transition temperatures and behaviour at elevated temperatures.Research limitations/implications: Free acid and water contend were not taken into consideration by defining the ideal stoichiometry. The investigated formulations cannot be direct applied on practical applications; fillers and additives must be added to them, which were not taken in consideration.Practical implications: The obtained results can support development of adhesives, engineering polymers and polymeric matrix for structural composites. Stabling the relation between component ratios to their behaviours is possible to define optimal performance ranges and to avoid excess of diisocyanate on polymers.Originality/value: Deep investigation of PU based material, obtained from renewable natural source (castor oil). The results can orientate development of materials for industrial applications and researches using other oils as polyol.
Evaluation of an AlCrN coated FSW tool
G.F. Batalha a,c,A. Farias,R. Magnabosco,S. Delijaicov
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: This paper aims to evaluate the wear performance of a physical vapor deposition (PVD) coating on cemented carbide (WC) tool used in friction stir welding FSW processing of Ti alloy sheets.Design/methodology/approach: A coating of AlCrN material was applied to a WC tool in order to increase its wear resistance, thermal shock stability and hot hardness. In comparison to the conventional coatings, the AlCrN coating system had a higher resistance to abrasive wear as well as higher hot hardness and oxidation resistance. FSW processing of Ti with a coated WC tool was expected to have better performance than an uncoated tool. Back Scattering Electron (BSE) imaging mode at scanning electron microscope was used to determine the main mechanism of tool wear, which was found to be hot adhesion and inter-diffusion of tool constituents with the workpiece materials.Findings: The tool degradation was evaluated by scanning electron microscopy in order to observe the main tool wear mechanism. The real contribution of the (Al,Cr)N coating layer could not be correctly evaluated, since there is no residual trace of its components at the worn tool. What was probably found left from the coating layer was the N component which formed the nitride TiN observed by EDS mapping. The parameter conditions were probably too severe, overcoming the layer limit strength.Research limitations/implications: The research were carried out as a preliminary evaluation and this initial results in the need of a further analysis that should be performed looking for a suitable tool material and coating optimization for the FSW processing of titanium alloys.Practical implications: Despite being successfully used in other manufacturing applications like machining operations in which friction and temperature are also high, the WC tool material and the coating had an unsatisfactory wear resistance, and the AlCrN coating was totally worn during the FSW processing. This suggests that new materials and coatings are still needed for FSW tools.Originality/value: FSW process is gaining importance as an industrial joining method, but the tool wear is still an important challenge to achieve efficient and economic operation. Because of the low thermal conductivity and high chemical reactivity of Ti, tools wear rapidly due to high temperature and strong adhesion. In order to achieve higher processing speeds, reducing heat at the interface tool/work material is required, as is the use of tool materials that have little or no chemical affinity.
Experimental study of influence factors on compression stress relaxation of ACM
D.J. dos Santos,L.B. Tavares,G.F. Batalha
Journal of Achievements in Materials and Manufacturing Engineering , 2011,
Abstract: Purpose: Purpose: of this paper is to investigate the influence of electron beam (EB) radiation, temperature and deformation on the compression stress relaxation behavior of UV curing polyacrylate rubber (ACM).Design/methodology/approach: ACM plugs were obtained by UV radiation curing. Some samples were post cured by EB dose of 250 kGy, providing two material conditions. The plugs were submitted to compression stress relaxation experiments (CSR) for 5.000 min on two temperature levels, 23°C and 90°C, and deformation levels of 10% and 15%. Results were analyzed using 2k Factorial Design, quantifying the influence of these factors on the maintained compression force.Findings: The results have shown an increase in the maintained compression force, respectively a decrease in the compression stress relaxation, for all EB irradiated ACM specimens along the entire measured period of time. The increase of the three analyzed factors has caused an increase of the maintained compression force. Through the 2k Factorial Design was possible to find out the deformation as the most relevant influence factor, followed by irradiation, as second influence factor and temperature.Research limitations/implications: ACM molecular structures were not physical-chemically investigated. Therefore, possible molecular structural changes, caused by EB radiation, were not described.Practical implications: Decreasing of compression stress relaxation implicates on increasing working life of sealing components made from the studied material, besides the improvement of sealing capacity of these components, even under reduced deformation conditions.Originality/value: The use of EB radiation as successful method to decrease compression stress relaxation of UV curing ACM rubber, has opened opportunities to industrial applications. Thus, provide knowledge about influence factors on ACM relaxation behavior.
Residual stresses modelling in hard turning and its correlation with the cutting forces
G.F. Batalha,S. Delijaicov,J.B. Aguiar,E.C. Bordinassi
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: This paper aims to study the cutting parameters influence (cutting speed, feed rate, cutting depth and tool radius nose) on the cutting forces (cutting force, feed rate cutting force and penetration cutting force) as well as on the residual stresses, in conical bearings made of steel DIN 100 CrMn6 hardened (62 HRc), searching correlations between the residual stresses and the cutting forces.Design/methodology/approach: A complete factorial planning was used to establish the correlations. At the same time, the cutting parameters influence in the microstructure of the material and it’s correlation with the residual stress was studied. A turning center machine and CBN inserts was employed for the tests. To the cutting force measurements was carried out using a piezoelectric dynamometer. The residual stresses measurements were carried out by X-ray diffractometry.Findings: The penetration cutting force was the most important factor in the residual stress generation, and it was influenced by the feed rate and the cutting depth. A correlation between the cutting depth and the residual stresses was established. The results do not showed any changes in the microstructure of the material, even when the greater cutting parameters were used.Research limitations/implications: The residual stress is one of the major causes of failures in bearings by contact fatigue, keeping this on mind, this work helps the developer to select correct cutting parameters in order to increase the machined workpiece life in service.Originality/value: This work were based on the real components (conical bearings), real cutting conditions and with these results were possible to make greater improvements in the manufacturing and in the quality of the studied parts.
Automotive body-in-white dimensional stability through pre-control application in the subassembly process
L.M. Sanches Jr,M.S. Filho,G.F. Batalha
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: This paper presents a case study and results of a pre-control method that allows for detectingsubassemblies variations with low investments using a methodology that search an improvement in quality ofautomotive body in white assemblies joining processes through dimensional control.Design/methodology/approach: Its main contribution is the statement of pre-control method to manage the weldassembly process since the early step of the project implementation just up to the production phase. Howeverthe pre-control method didn’t substitute any other dimensional control, the scope here was to demonstrate thatsuch alternative method offers a reliable in control process of the dimensional changes and their repeatability, asit only complement the current methods used in the automotive industry. It is emphasized here the dimensionalcontrol as well as some process quality tools.Findings: It is showed the results and impact of a pre-control method in the weld assembly process,highlighting dimensional stability improvements and annual cost reduction through reducing rework hoursand scrap parts quantity.Practical implications: The pre-control, revealed as a simplified tool application and can be used by theproduction operators with low investment cost and operation.Originality/value: The application the pre-control method is more efficient in subassemblies manufacturedfrom manual process or that allows greater interaction of the production operator.
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