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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society of Tribologists and Lubrication Engineers
Journal Basic Information
Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 23, Issue 6 - Dec 2007
Volume 23, Issue 5 - Oct 2007
Volume 23, Issue 4 - Aug 2007
Volume 23, Issue 3 - Jun 2007
Volume 23, Issue 2 - Apr 2007
Volume 23, Issue 1 - Feb 2007
Selecting the target year
A Study on the Elastohydrodynamic Lubrication of Roller Contact according to Axial Profiles
Jang, Si-Youl ; Kim, Wan-Doo ; Kim, Min-Chul ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 187~194
The profile of the roller in the axial direction is the main design factor in order to increase endurance life against the contact fatigue due to the stress concentration along the edge of the roller. Even under the elas-tohydrodynamic lubrication (ehl) conditions, the stress concentration along the edge of the roller greatly worsens the fatigue life both for the roller and contacting body. In this study, roller contacts of finite axial length are studied for the film thickness and pressure of ehl. For the real contact behaviors under the ehl conditions, multigrid and multi-level method is applied so that much higher loading conditions can be investigated. Several axial profiles of roller are investigated to verify how both ehl film and pressure are generated and some of them are recommended for the ehl contact condition.
SEM/EDX Analysis on the Composition and Surface Defect in a Pin Bushing Bearing for an Automotive Engine
Kim, Chung-Kyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 195~200
This paper presents the friction induced scuffing and wear defects analysis of a pin bushing bearing based on the chemical composition using a scanning microscopy (SEM) and an energy dispersive X-ray analyzer (EDX). The SEM/EDX system, which may provide good information on the surface thermal defects and chemical compositions, provides impurities such as an aluminum, a silicon, a ferrous component and an oxygen, especially. The EDX measured results show that the oxygen may reduce the strength and a hardness of a pin busing, which may lead to a scuffing and a seizure on the rubbing contact surface. The current technology fabricated by a sintering for a pin bushing bearing should be modified or changed to reduce the oxygen composition and the impurities in pin bushing materials.
A study on lubrication characteristics between piston ring and cylinder bore of bent-axis type piston pump for vehicle
Jung, Jae-Youn ; Cho, Ihn-Sung ; Song, Kyu-Keun ; Baek, Il-Hyun ; Oh, Seok-Hyung ; Jung, Seok-Hoon ; Jeong, Yong-Wook ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 201~206
The bent-axis type piston pump which is driven by the piston rod works on the way that the piston rod drives the cylinder block, so the taper angle of the piston rod and the swivel angle between the cylinder block and the shaft are very important design factors. If the above factors cannot satisfy the conditions of optimum design, the friction loss between the cylinder bore and the piston increases, and the pump can even fail to work under conditions of severe friction and wear. Since the piston reciprocates in the cylinder bore with high velocity, and at the same time it rotates on its own axis and revolves on the center of the cylinder block, the decrease of the volume efficiency generated on account of the leakage between the cylinder bore and the piston. Therefore, to prevent this case, the piston ring is designed at the end of the piston, and the friction characteristics between the piston ring and the cylinder bore are in need of research due to its great influence on the performance of piston pump. Thus, in this paper, the elastic hydraulic oil's lubrication analyses of the film thickness, the pressure distribution, and the friction force, and so on, have been performed, and the lubrication characteristics between the piston ring and the cylinder bore are explored by the results of the numerical analysis, and it is contributed to realize the higher efficiency and the more advanced performance of the bent-axis type piston pump.
Aeration Effects on the Performance of Turbocharger Journal Bearing under Constant Load Operating Condition
Chun, Sang-Myung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 207~218
Turbocharger bearings are under the circumstance of high temperature, moreover rotated at high speed. It is necessary to be designed overcoming the high temperature. So the type of oil inlet port, the inlet oil temperature and the sort of engine oil should be designed, controlled and selected carefully in order to reduce the bearing inside temperature. In this study, the influence of aerated oil on a high-speed journal bearing is also examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil inlet port's type, oil aeration level and shaft speed. It is found that the type of oil inlet ports and shaft speed play important roles in determining the temperature and pressure distribution, then the friction in a journal bearing at high speed operation. Also, the results show that, under extremely high shaft speed, the high shear effects on aerated oil and the high temperature effects are canceled out each other. So, the bearing load and friction show almost no difference between the aerated oil and pure oil.
The Dynamic Performance Analysis of Foil Journal Bearings Considering Coulomb Friction: Rotating Unbalance Response
Kim, Kyung-Woong ; Lee, Dong-Hyun ; Kim, Young-Cheol ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 219~227
The dynamic performance of air foil bearings relies on a coupling between a thin air film and an elastic foil structure. A number of successful analytical techniques to predict dynamic performance have been developed. However, the evaluation of its dynamic characteristic is still not enough because of the mechanical complexity of the foil structure and strong nonlinear behavior of friction force. This work presents a nonlinear transient analysis method to predict dynamic performance of foil bearings. In this method, time dependent Reynolds equation is used to calculate pressure distribution and a finite element method is used to model the bump foil structure. The analysis is treated with a direct implicit integration technique that can handle nonlinear problems and the stick-slip algorithm is used to consider friction force. Using this method the response to the mass unbalance excitation is investigated for various design parameters and operating conditions. The results of analysis show that foil bearing is very effective on the restriction of vibration at the resonance frequency compared to the rigid surface bearings and the effectiveness depends on the operating conditions, static load and a amount of mass unbalance. In addition, there exist optimum values of friction coefficient, bump foil stiffness and number of circumferential slit with regards to minimizing dynamic response at the resonance frequency. These optimum values are system dependent.
Failure Studies on the Wear Scars of an Automotive Tire
Lee, II-Kwon ; Kim, Chung-Kyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 228~233
This paper presents the case studies on the friction related wears of an automotive tire, which is strongly connected to the safety and comfort of a driver during a running of a car. Wear scars of a tire tread are affected by various causes such as an air pressure, a wheel alignment, a driving speed, road conditions, starting and braking habits of a driver. The data were collected from used tires for a replacement at the car service center. Most of the wear problems came from the improper repair and adjustment of revolving components, which cause an unbalanced wear of a tread part of a tire. Thus, the regular checking of a tire radically reduces the wear scars of a tire and may increase a driving safety and a fuel economy of a car and a wear life of a tire.
A study on the Noise Reduction of Vane-type Vacuum pump Mounted on Alternator using Design of Experiments
Park, Soon-Sik ; Kim, Yong-Chan ; Kim, Byoung-Duk ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 234~239
Recently one of the automobile customer's greatest concerns is quietness in a vehicle along with various functional requirements such as comfort, stability, mobility etc. Therefore car makers place more weight on vehicle noise. Especially, in the case of diesel engine, as the noise level of engine becomes more silent by the development of engineering technology. The noise of alternator with vacuum pump has been able to be noticed enough becoming an issue on vehicles. In this study vacuum pump noise on alternator was identified andclassified into five types. DOE was applied to induce the statistical analysis result to reduce the vacuum pump noise. It was done by subjective listening. Design and statistical analysis are done with Minitab software. This work provides dominant elements of vacuum pump noise on alternator and can be the basis of furture studies.
Design of Air Turbine and Air Bearing for Dental Handpiece
Hwang, Pyung ; Park, Sang-Shin ; Sohn, Jeong-L. ; Kwon, Seong-In ; Kim, Do-Hyung ; Kim, Woo-Seok ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 5, 2007, Pages 240~247
The design process of the dental handpiece is described. The parameters of the high speed air turbine are estimated. The effect of supply hole on the stiffuess and damping of the air bearing for handpiece is studied numerically. The Reynolds equation is solved by using the divergence formulation and the perturbation method. The test rig is built and the test procedure is developed for the turbine rotational speed measurement by using Fourier transform of noise generated by the turbine during steady operation.