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Jorge H O Seabra - One of the best experts on this subject based on the ideXlab platform.
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power loss and load distribution models including frictional effects for spur and helical Gears
Mechanism and Machine Theory, 2016Co-Authors: Pedro Marques, Ramiro C. Martins, Jorge H O SeabraAbstract:Abstract Friction between meshing Gear Teeth are amongst the most influential power loss sources in a Gearbox near nominal operating conditions. Speed, load and coefficient of friction are some of the most important factors regarding frictional losses in Gears. The aim of this work is to introduce Gear load sharing models for spur and helical Gears taking into account elastic and frictional effects allowing to do more refined estimations of Gear friction losses.
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influence of tooth profile and oil formulation on Gear power loss
Tribology International, 2010Co-Authors: Luis Magalhães, Ramiro C. Martins, Cristiano Locateli, Jorge H O SeabraAbstract:Abstract Nowadays power losses are a main concern in transmission systems and the friction between Gear Teeth during the meshing cycle is one of the main sources. The friction losses reduction is mandatory to promote lower energy consumption, lower operating temperatures, lower oil oxidation and lower risk of failures. In this study the power losses reduction is obtained using two different approaches: using lower modulus helical Gears and significant positive profiles shifts and using Gear oil formulations with different base oils. The adopted geometries proved to reduce the power losses considerably, promoting a reduction of oil operating temperature up to 20 K.
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surface initiated tooth flank damage part ii prediction of micropitting initiation and mass loss
Wear, 2010Co-Authors: Jose A Brandao, Jorge H O Seabra, J CastroAbstract:Following the first part of this work, where a numerical model of surface initiated fatigue damage was presented, that model is applied here to the prediction of micropitting and mass loss of Gear Teeth. This is achieved by simulating a real micropitting test and by comparing it to the actual test results. On the way, a possible approximation to the mechanism by which mass is removed from the flank surface is discussed.
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coefficient of friction in mixed film lubrication Gears versus twin discs
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2007Co-Authors: J Castro, Jorge H O SeabraAbstract:AbstractThis work compares the friction between two contacting discs with the friction between Gear Teeth, using a mixed film lubrication model developed for the evaluation of contact pressure and shear stress fields [5]. Such model is used to analyse twin-disc contacts with smooth surfaces and Gear Teeth contacts with rough surfaces, both lubricated with an additive-free ISO VG 150 mineral oil.Experimental lubricant traction curves [4], measured in a twin-disc machine under full film elastohydrodynamic (EHD) lubrication (Λ > 2), were used to evaluate the lubricant rheological parameters, taking into account the surface roughness of the contacting discs. Experimental power loss measurements, made during Gear efficiency tests performed in a Forschungsstelle fur Zahnrader und Getriebebau (FZG) test rig [4], were used to evaluate the average friction coefficient between Gear Teeth along the meshing line, considering the surface roughness of the tooth flanks.The experimental friction coefficients between Gear...
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coefficient of friction in mixed film lubrication Gears versus twin discs
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2007Co-Authors: J Castro, Jorge H O SeabraAbstract:AbstractThis work compares the friction between two contacting discs with the friction between Gear Teeth, using a mixed film lubrication model developed for the evaluation of contact pressure and shear stress fields [5]. Such model is used to analyse twin-disc contacts with smooth surfaces and Gear Teeth contacts with rough surfaces, both lubricated with an additive-free ISO VG 150 mineral oil.Experimental lubricant traction curves [4], measured in a twin-disc machine under full film elastohydrodynamic (EHD) lubrication (Λ > 2), were used to evaluate the lubricant rheological parameters, taking into account the surface roughness of the contacting discs. Experimental power loss measurements, made during Gear efficiency tests performed in a Forschungsstelle fur Zahnrader und Getriebebau (FZG) test rig [4], were used to evaluate the average friction coefficient between Gear Teeth along the meshing line, considering the surface roughness of the tooth flanks.The experimental friction coefficients between Gear...
M. Amarnath - One of the best experts on this subject based on the ideXlab platform.
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surface contact fatigue failure assessment in spur Gears using lubricant film thickness and vibration signal analysis
Tribology Transactions, 2015Co-Authors: M. Amarnath, C SujathaAbstract:Gears are very common machine elements that are used to transmit power. During power transmission, the Gear Teeth are subjected to high contact pressure, leading to wear and tear, even though adequate lubrication is used. When Gears operate near their maximum load capacity, very high contact pressure occurs at the mesh interference. This may lead to partial breakdown of the lubricant film at the Gear Teeth contact surface, thereby triggering distributed faults on Gear Teeth, viz. scuffing, scoring, spalling, pitting, and mild wear. Currently there are three different approaches to the detection of faults in Geared systems: vibration analysis, oil/wear particle analysis, and acoustic signal analysis. Generally, in an industrial environment, vibration analysis and oil/ wear particle analyses are conducted independently, but of late there are requirements in the diagnostic world for more reliable and effective diagnostic information regarding fault growth in machinery components. In the present work, experim...
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experimental investigation to establish correlation between specific film thickness and sound signals in a spur Gear system
Transactions of The Korean Society for Noise and Vibration Engineering, 2014Co-Authors: M. AmarnathAbstract:Gear transmission system is widely applied in engineering. As the problem of contact fatigue, wear, lubrication failure etc, the condition of Gear Teeth contacts will be worse. The vibration and sound signals in the Gear system will be affected by the some failures like scuffing, abrasive wear and spalling due to the deterioration of Gear Teeth surface. By studying the estimation of specific film thickness, measurement of reduction in tooth thickness, visual examination of wear mechanisms on the Gear Teeth and their effects on the statistical parameters of vibration and sound signals, the research obtained the satisfactory results on accessing the surface fatigue wear in a spur Gear system. The paper utilizes the relationship between statistical parameters obtained from sound signals and Stribeck curve to confirm the hypothesis of dependency of surface fatigue wear, specific film thickness.
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experimental investigations of surface wear assessment of spur Gear Teeth
Journal of Vibration and Control, 2012Co-Authors: M. Amarnath, Sujatha Chandramohan, Swarnamani SeetharamanAbstract:The most common Gear wear mechanisms, such as micropitting, pitting and scouring often occur in the early stage of failure. For the Geared system operating in the presence of such surface failures, the load acts only over a finite region and contact stress tends to increase enormously in the contact area of the mating Teeth surface. The propagation of tooth damage causes instantaneous reduction in tooth stiffness. The vibration signal of Gear transmission varies as the stiffness changes. Therefore the connection between surface fatigue failure, stiffness and vibration signal are of significant importance in monitoring Gear defects. The purpose of this study is to conduct experimental investigations on the measurement of reduction in the Gear Teeth stiffness along with vibrations parameters. A pair of spur Gears was tested under an accelerated test condition in an oil bath lubricated back-to-back Gearbox. Experimental measurement of stiffness was carried out using modal analysis in conjunction with a theor...
Soren Andersson - One of the best experts on this subject based on the ideXlab platform.
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simulation of mild wear in helical Gears
Wear, 2000Co-Authors: Anders Flodin, Soren AnderssonAbstract:A computer model for simulation of the wear behaviour in helical Gears has been developed. The method used can deal with tooth modifications and different profiles. The authors have studied the effects of wear previously but only in a two-dimensional perspective. The objective of the paper is to compare the wear behaviour of Gears using different approaches. The Gear Teeth in this model are regarded as thin uncoupled slices; the slicing method is valid when the contact area is narrow in the rolling direction, which is the case for contacting Gear Teeth. The pressure distribution on each slice is calculated using the well-known theories of Hertz assuming an infinitely wide line-contact. When the pressure and velocity on the surfaces are known, a modified Archard's wear equation is applied to calculate wear depths on the Teeth. The simulation is an initial value problem since a complete mesh cycle is repeated a number of times with gradually changing surfaces due to the wear, which is being integrated over each time step.
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simulation of mild wear in helical Gears
AUSTRIB 98 Tribology at Work: Proceedings of the 5th International Tribology Conference in Australia Brisbane 6-9 December 1998, 1998Co-Authors: Anders Flodin, Soren AnderssonAbstract:A computer model for simulation of the wear behaviour in helical Gears has been developed. The method used can deal with tooth modifications and different profiles. The authors have studied the effects of wear previously but only in a two-dimensional perspective. The objective of the paper is to compare the wear behaviour of Gears using different approaches. The Gear Teeth in this model are regarded as thin uncoupled slices, the slicing method is valid when the contact area is slender in the rolling direction, which is the case for contacting Gear Teeth. The pressure distribution on each slice is calculated using the well-known theories of Hertz assuming an infinitely wide line-contact. When the pressure and velocity on the surfaces are known, a modified Archard's wear equation is applied to calculate wear depths on the Teeth. The simulation then becomes an initial value problem since a complete mesh cycle is repeated a number of times with gradually changing surfaces due to the wear that is being integrated over each time step.
Jorge Castro - One of the best experts on this subject based on the ideXlab platform.
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Comparative overview of five Gear oils in mixed and boundary film lubrication
Tribology International, 2012Co-Authors: Jose A. Brandao, Mathilde Meheux, Fabrice Ville, Jorge H. O. Seabra, Jorge CastroAbstract:Stribeck curves were obtained from numerous traction tests performed under a wide range of operating conditions on several fully formulated Gear oils with mineral, PAD and ester basestocks. These curves, which make use of a modified Stribeck parameter also presented here, were examined in order to analyse the influence of the operating conditions and of the Gear oils on the coefficient of friction in mixed and boundary film lubrication. Particular attention was given to the coefficient of friction in boundary film lubrication. Theses Stribeck curves might be helpful in understanding the evolution of the coefficient of friction between Gear Teeth along the meshing line.
N Ganesan - One of the best experts on this subject based on the ideXlab platform.
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technical note static contact stress analysis of a spur Gear tooth using the finite element method including frictional effects
Computers & Structures, 1994Co-Authors: S Vijayarangan, N GanesanAbstract:The literature available on Gear tooth contact stress problems is not very extensive and that available does not explain the method by which analysis was carried out. In this paper an attempt has been made to study the contact stresses of a pair of mating Gear Teeth, under static conditions, by using a two-dimensional finite element method and the Lagrangian multiplier technique. The contact condition at the neighbouring node pair, namely, the contact existing over a number of node pairs in the contact zone, has been considered. To study the effect of friction between the mating Gear Teeth a range of average static friction coefficients, from 0.0 to 0.3, has been considered. The actual length of contact against the calculated length of contact is discussed. The variation of contact stress along the contact surface in a direction normal to the mating surfaces, which will give an idea about the depth of hardening required, is also presented.
