The Experts below are selected from a list of 226368 Experts worldwide ranked by ideXlab platform
Jorge H O Seabra - One of the best experts on this subject based on the ideXlab platform.
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gearbox Power Loss part ii friction Losses in gears
Tribology International, 2015Co-Authors: Carlos M.c.g. Fernandes, Pedro Marques, Ramiro C. Martins, Jorge H O SeabraAbstract:Abstract The second part of the study presents an extensive campaign of experimental tests in an FZG test rig. An average coefficient of friction between meshing gears was devised from the experimental results. Several aspects regarding the meshing gears Power Loss are discussed such as gear Loss factor, coefficient of friction and the influence of gear oil formulation (wind turbine gear oils).
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Influence of gear Loss factor on the Power Loss prediction
Mechanical Sciences, 2015Co-Authors: Carlos M.c.g. Fernandes, Pedro Marques, Ramiro C. Martins, Jorge H O SeabraAbstract:Abstract. In order to accurately predict the Power Loss generated by a meshing gear pair the gear Loss factor must be properly evaluated. Several gear Loss factor formulations were compared, including the author's approach. A gear Loss factor calculated considering the load distribution along the path of contact was implemented. The importance of the gear Loss factor in the Power Loss predictions was put in evidence comparing the predictions with experimental results. It was concluded that the gear Loss factor is a decisive factor to accurately predict the Power Loss. Different formulations proposed in the literature were compared and it was shown that only few were able to yield satisfactory correlations with experimental results. The method suggested by the authors was the one that promoted the most accurate predictions.
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Power Loss Prediction in High-Speed Roller Bearings
Tribology and Interface Engineering Series, 2008Co-Authors: Daniel Nelias, Jorge H O Seabra, L. Flamand, G. DalmazAbstract:Abstract Friction between the various elements in a rolling bearing results in Power Loss and heat generation. Therefore, an estimation of the rolling bearing Power Losses is necessary to refine lubrication techniques and to optimize machine component design. A new model which predicts and locates Power Losses in a high-speed cylindrical roller bearing, operating under purely radial load, is presented. Its new features come from the consideration of both cage action and the effect of lubricant film thickness in the computation of bearing kinematics at equilibrium. Lubricant rheological properties are used in order to calculate hydrodynamic and elastohydrodynamic forces in each lubricated contact. This model considers cage and roller kinematics to be unknown. These are obtained by solving the equations of motion for each bearing element. The computation and the location of Power Losses are given by the friction forces and the sliding speeds among the various bearing elements, i.e., contact between roller and inner or outer ring, roller edge-race flange, roller-cage pocket and cage-ring pilot surface. The authors compare first the values of the calculated Power Loss with experimental data to assess the program's predictive capability. Afterwards the model is used to estimate and locate Power Losses in a well-lubricated high-speed roller bearing. Results show that the total Power Loss varies strongly with the rotational speed, the lubricant inlet temperature and the oil flow through the bearing. Nevertheless, it is less sensitive to radial load. Power Loss results are also given as a function of the bearing internal geometry.
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austempered ductile iron adi gears Power Loss pitting and micropitting
Wear, 2008Co-Authors: Ramiro C. Martins, Jorge H O Seabra, Luis MagalhaesAbstract:Abstract This work is a systematic experimental evaluation of austempered ductile iron (ADI) as a gear material. The evaluation of this ADI as a gear material concerns two main aspects: Power Loss and contact fatigue resistance (pitting and micropitting). All gear tests were performed on the FZG test rig. For the micropitting and Power Loss evaluation two gear lubricants were considered. The results show that ADI is a material to be considered by gear designers, once the energetic behavior of ADI gears is similar to carburizing gears, being although slightly worst at high input Power. The pitting life is infinite for contact pressures below 1.2 GPa. The best wear behavior of ADI is attained if combined with ester biodegradable lubricant, both on Power Loss and micropitting tests, so the best overall behavior of ADI gears is obtained with biodegradable ester lubricant.
Yinhong Liao - One of the best experts on this subject based on the ideXlab platform.
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transient Power Loss density of electromagnetic pulse in debye media
IEEE Transactions on Microwave Theory and Techniques, 2015Co-Authors: Kama Huang, Yinhong LiaoAbstract:This paper is to point out the mistakes of previous expression of Power Loss density of the electromagnetic pulse (EMP) in Debye media. We derive the precise expression of transient Power Loss density both from the electrodynamic (ED) approach and equivalent circuit (EC) approach. In the ED approach, the expression is derived from the energy conservative law and Debye equation. For the harmonic field, the expression reduces to the well-known formula. The physical meaning can be clearly explained in the EC approach. The expression derived from the EC approach is consistent with that from the ED approach. A 1-D example is used to show the negative Power Loss of the EMP in Debye media and the error of temperature rise calculated from the previous expression.
Aysegul Kahraman - One of the best experts on this subject based on the ideXlab platform.
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A windage Power Loss model for spur gear pairs
Tribology Transactions, 2010Co-Authors: Srini Seetharaman, Aysegul KahramanAbstract:This article proposes a simplified fluid mechanics–based model to predict the windage Power Loss of a spur gear pair operating under jet lubrication conditions. In this model, the total windage Power Loss is defined as the sum of (a) the Losses associated with the interactions of individual gears with the air or air–oil mixture and (b) the Losses due to pocketing/squeezing of the same medium at the gear mesh interface. The first group of Losses is modeled through a formulation for air drag forces induced on each rotating gear body along its faces and periph-ery (circumference). The pocketing Power Loss is modeled an-alytically through a compressible fluid flow formulation. The windage Power Loss model predictions are compared to pub-lished gear pair windage experiments and empirical formulae to assess their accuracy. Results of a parametric study are also presented to quantify the impact of key system parameters as well as individual contributions of each component to the total windage Power Loss.
Kama Huang - One of the best experts on this subject based on the ideXlab platform.
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transient Power Loss density of electromagnetic pulse in debye media
IEEE Transactions on Microwave Theory and Techniques, 2015Co-Authors: Kama Huang, Yinhong LiaoAbstract:This paper is to point out the mistakes of previous expression of Power Loss density of the electromagnetic pulse (EMP) in Debye media. We derive the precise expression of transient Power Loss density both from the electrodynamic (ED) approach and equivalent circuit (EC) approach. In the ED approach, the expression is derived from the energy conservative law and Debye equation. For the harmonic field, the expression reduces to the well-known formula. The physical meaning can be clearly explained in the EC approach. The expression derived from the EC approach is consistent with that from the ED approach. A 1-D example is used to show the negative Power Loss of the EMP in Debye media and the error of temperature rise calculated from the previous expression.
Grzegorz Rotta - One of the best experts on this subject based on the ideXlab platform.
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On the Possibilities of Decreasing Power Loss in Large Tilting Pad Thrust Bearings
International Scholarly Research Notices, 2013Co-Authors: Michał Wasilczuk, Grzegorz RottaAbstract:Different systems of direct oil supply have been developed in order to facilitate efficient introduction of fresh lubricant to the oil gap and reduction of churning Power Loss in tilting pad thrust bearings. Up to now there is no documented application of the supply groove in large thrust bearings used in water Power plants. The results of modeling lubricant flow in the lubricating groove of a thrust bearing pad will be presented in the paper. CFD software was used to carry out fluid film calculations. Such analysis makes it possible to modify groove geometry and other parameters and to study their influence on bearing performance. According to the results a remarkable decrease in total Power Loss due to avoiding churning Losses can be observed in the bearing.
