The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform
Sa'ad Ahmed Saleh Al Kazzaz - One of the best experts on this subject based on the ideXlab platform.
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Isolation and identification of Dry Bearing faults in induction machine using wavelet transform
Tribology International, 2009Co-Authors: Girish Kumar Singh, Sa'ad Ahmed Saleh Al KazzazAbstract:Abstract Any vibration signal obtained from electromechanical systems contains a level of random changes. These random changes in the measured signal may be due to the random vibrations that can be related to the health of the machine for some faults such as Dry Bearing fault or Bearing ageing. The presence of Dry Bearing fault, which is caused by the lack of lubricant, increases the level of random vibrations as compared to those obtained in healthy Bearing machine. If these random vibrations could be isolated from the measured signal, useful information about Bearing health may be obtained. Therefore, in this paper, signals (three line to line voltages, three currents, two vibration signals, four temperatures and one speed signal) obtained from the monitoring system are treated and analyzed using wavelet transform to correlate it to the Dry Bearing faults in induction machine. In this study, on-line analysis of the acquired signals has been performed using C ++ , while MATLAB has been used to perform the off-line analysis.
Katsuhiko Nakajima - One of the best experts on this subject based on the ideXlab platform.
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thermal contact resistance between balls and rings of a Bearing under axial radial and combined loads
Journal of Thermophysics and Heat Transfer, 1995Co-Authors: Katsuhiko NakajimaAbstract:The thermal contact resistance between the balls and the inner and outer rings of a space-use deep groove ball Bearing is investigated assuming that heat transfer between smooth contacting elements occurs through the elastic contact areas. It is also assumed that the stationary Bearing sustains axial, radial, or combined loads under a steady-state temperature condition. The shapes and sizes of the contact areas are calculated using the Hertzian theory. In particular, the contact force for the axial load is determined with careful consideration of the change in the contact angle induced by elastic deformation at the contact area. The correlation between the experimental data and the calculated values confirms the validity of the prediction method for the thermal contact resistances between the elements of a Dry Bearing with a surface roughness of less than 0.5 x 10~ m under the mean temperature of less than 353 K, and temperature differences across the rings of less than 35 K.
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Experimental investigation of the thermal contact resistance of a space-use deep groove ball Bearing
Journal of the Japan Society for Aeronautical and Space Sciences, 1992Co-Authors: Katsuhiko NakajimaAbstract:An investigation is conducted to experimentally verify an analytical method that determines the thermal contact resistance between the balls and the inner and outer rings of a space-use ball beardng. A single row Bearing made from stainless steel 440C is tested in a vacuum environment, and steady-state temperature distributions are measured to evaluate the heat flow across the stationary Bearing. Test results are given for the conditions of axial, radial and combined loading. Excellent agreement between the measured and predicted values of the thermal contact resistance is found under all types and magnitudes of the applied loads. It is concluded that the proposed calculation method accurately predicts the thermal contact resistance between the elements of a Dry Bearing with smooth contact surfaces.
J K Lancaster - One of the best experts on this subject based on the ideXlab platform.
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Composites for Aerospace Dry Bearing Applications
Friction and Wear of Polymer Composites, 2012Co-Authors: J K LancasterAbstract:Abstract Most Bearings associated with flight-control applications in fixed wing aircraft and helicopters comprise polymer-based composites in the form of thin layers, ~0.3 mm thick, adhesively bonded to a metal substrate. The various types of composite used for this purpose are described and information given on how their friction and wear properties depend on the conditions of sliding; stress, temperature, counterface metal, contamination by fluids, type of loading, and various kinematic factors associated with the Bearing design. A long-standing objective has been to relate friction and wear performance to composite structures and compositions and some results are given from recent research describing progress towards this end. Finally, brief mention is made of future trends and requirements for composites in Dry-Bearings, with particular reference to high temperature applications.
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Assessment of the Wear of Composite Coatings in Reciprocating Line Contact Conditions
Selection and Use of Wear Tests for Coatings, 1Co-Authors: J K LancasterAbstract:Aerospace Dry-Bearing materials commonly consist of a plastics-composite coating, typically 200 to 400 μm in thickness, adhesively bonded to a metal substrate. These materials are intended for use at high loads and low speeds, and assessments of their performance in full-scale Bearing tests are expensive and time-consuming. This paper describes an accelerated test procedure for determining the wear behavior of such coatings, in which a small coated strip is loaded in nominal line contact against a rotating metal ring. The advantages and limitations of the method are discussed and examples given relating to (I) comparative screening of commercially available Bearing liners, (2) effects of coating structure and composition on wear, (3) importance of the adhesive bond between the coating and its substrate, and (4) assessment of which particular parameters, amongst the many known to influence sliding behavior, are most important to the wear of these coatings. One problem identified by the work is the need for more information on the mechanical properties of thin composite coatings.
Nitin Borade*1 Dhananjay & Pise2 - One of the best experts on this subject based on the ideXlab platform.
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EXPERIMENTAL INVESTIGATION OF POLYMER JOURNAL Bearing UNDER Dry CONDITION
2018Co-Authors: Nitin Borade*1 Dhananjay & Pise2Abstract:In this study, the effect of contact pressure, sliding velocity and sliding distance on friction, wear and contact temperature of polymer based Bearings manufactured from “Polytetrafluoroethylene (PTFE)” & it’s composite of “20% Bronze filled PTFE” in Drycondition have been investigated and evaluatedThe experiments were carried using full factorial design. Most of laboratory investigations are done on “test rigs” like pin-on-disc or pin-on-ring. But Bearings have special geometrical and kinematical characteristics. The friction & wear results of the sample materials used on these setups are then related to the actual conditions which may not depict true performance of the Bearings. Hence to overcome this drawback, ‘Dry Bearing Test Rig’ is used which gives friction & wear analysis by simulating the conditions in actual practice, i.e. test Bearing being mounted on the shaft and enclosed in support bush. Hence simulated analysis of friction & wear of Bearings can be performed and results give closeness to the true values of frictional force and wear of Bearing
Girish Kumar Singh - One of the best experts on this subject based on the ideXlab platform.
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Isolation and identification of Dry Bearing faults in induction machine using wavelet transform
Tribology International, 2009Co-Authors: Girish Kumar Singh, Sa'ad Ahmed Saleh Al KazzazAbstract:Abstract Any vibration signal obtained from electromechanical systems contains a level of random changes. These random changes in the measured signal may be due to the random vibrations that can be related to the health of the machine for some faults such as Dry Bearing fault or Bearing ageing. The presence of Dry Bearing fault, which is caused by the lack of lubricant, increases the level of random vibrations as compared to those obtained in healthy Bearing machine. If these random vibrations could be isolated from the measured signal, useful information about Bearing health may be obtained. Therefore, in this paper, signals (three line to line voltages, three currents, two vibration signals, four temperatures and one speed signal) obtained from the monitoring system are treated and analyzed using wavelet transform to correlate it to the Dry Bearing faults in induction machine. In this study, on-line analysis of the acquired signals has been performed using C ++ , while MATLAB has been used to perform the off-line analysis.
