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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Tribologists and Lubrication Engineers
Journal Basic Information
Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
Editor in Chief :
Volume & Issues
Volume 13, Issue 4 - Dec 1997
Volume 13, Issue 3 - Sep 1997
Volume 13, Issue 2 - Jun 1997
Volume 13, Issue 1 - Mar 1997
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Power Transmission Mechanism of Electrorheological Clutch Part III: Experimental considerations on performance of ER clutch
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 1~9
ER clutch is a device using ER fluid, so called "intelligent material" and is a power transmission system controlled with electric field strength. In this paper(Part III), the behavior of ER clutch under proper conditions was investigated experimentally and compared to theoretical analyses developed from Part I, II. Considering the optimum design concept proposed from Part I, the concentric cylinder type of ER clutch was designed and the experimental apparatus for the performance test was constructed. The comparisons made indicated that the power transmission model of ER clutch and the temperature rise model of ER fluid developed from Part I, II were acceptable for engineering design calculations.culations.
An Experimental Study of Thermoelastic Instability in Automotive Ventilated Disk Brake
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 10~17
The present study describes an experimental investigation of temperature fluctuations associated with thermal instability. Surface temperatures of brake disk and pad were monitered at various locations in a caliper type brake system during drag braking conditions. It was found that the thermal instability appeared in pad more seriously than in disk. The temperatures at various circumferential positions fluctuate synchronously, whereas the center temperature fluctuates with 180
phase difference from the outer and inner radius temperatures. The temperature and amplitude of the temperature perturbations are increased due to the increase of contact area in the center location. It was also found that the thermal instability was dominantly determined by the increase of rotation speed and pressure. And the modification of ventilation path could retard the onset of thermal instability.
Deformation and Fracture Behavioos of Soda-lime Glass by Sliding Microindentation
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 18~25
The various deformation and fracture behaviors under light loads in soda-lime glass under sliding Vickers indentation have been studied. In soda-lime glass, deformation and fracture behaviors can be classified into four different patterns by applied load. At very light load (<0.1N), plastic deformation only occurred. At low loads (0.1~0.8N), median crack, appear. At intermediate loads (0.8~3.0N), median and lateral cracking occurred leading to a large chipping. At high loads (3.0~6.0N), a crushed zone was observed with median crack. The friction experiment finds that the increasing in the friction coefficients coincides with the onset of crushing in soda-lime glass.
Heat Generation Characteristics of Ball Bearing for Operating Conditions
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 26~32
The heat generation of the angular contact and the deep groove ball bearing is studied experimentally and numerically. The temperature variation of the inner and outer races and the temperature increase distribution are measured for the shaft rotational speeds, preloads, viscosities of the lubricant and lubrication methods. The measured temperature distributions are used as the input data of the numerical simulation to estimate the heat generation rate at the bearing. The temperatures of the inner and outer race increase more rapidly and approach faster to their steady values as the rotational speed increases. The optimal viscosity of the oil to minimize the heat generation is 8~10 cSt at 4
when the oil-air lubrication method is adopted. The heat generation of the bearing increases with the rotational speed and depends more on the lubrication method than on the preload variation.
The Effect of Gasoline Engine Oil Degradation and Piston Temperature on Carbon Deposit Formation; Part I-Characteristics of deposit formation on gasoline engine
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 33~39
In order to establish a new temperature criterion to prevent the pistons from ring sticking due to deposit formation, bench test and engine test were performed. The effects of oil degradation and temperature on deposit formation was studied by a modified panel coking test. Oil degradation was analyzed by FTIR. Oil oxidation and nitration were selected as a factors to evaluate oil degradation. Bench test results show that oil oxidation is more effective to the deposit formation than oil nitration. And the temperature increase accelerates deposit formation and deposit formation increase rapidly above 26
. Especially, in case of degraded oil, the deposit formation increases so rapidly that ring sticking can occur. The effect of piston temperature on the deposit formation was confirmed by engine test.
Analysis of the Air Journal Bearings with Two Circumferential Grooves
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 40~46
The externally pressurized air journal bearings which have two circumferential grooves with inherently compensated restrictors are analyzed. Two circumferential grooves with restrictors are made on the bearing surface in order to increase the stiffness and damping coefficients. In this paper, the dynamic characteristics such as stiffness and damping coefficients of this type of bearings are calculated. As a result of theoretical analysis, it is verified that there exist the groove depth and the distance between two grooves which generate the maximum stiffness at the given bearing dimensions.
Characteristics of Friction Torques and Lubrication in High Speed Angular Contact Ball Bearings
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 47~52
Friction torques, electrical contact resistances and bearing temperatures were measured on high speed angular contact ball beatings for the spindle of machine tools. The test bearings ran with oil-air lubrication at the thrust loads from 320 N to 1920 N and at the rotational speed of up to 12000 rpm. Electrical contact resistances between balls and races were measured to evaluate the formation of the lubricant film in the contact area. The test results with sufficient lubrication showed that the variations of friction torques were sensitive to the thrust loads and the rotational speeds, and that the friction torques were higher than those with insufficient lubrication. With insufficient lubrication and high thrust loads, the collapse of the lubricant film was detected even at a high rotational speed. It was concluded that these high speed beatings to run in condition of fluid lubrication should require monitoring not only the temperature increase of the bearing but also the lubricant film formation in contact areas resulting from the change in the applied load and the lubricant amount.
An Analytical Study on Camshaft Locus at Camshaft Bearing in a Direct Acting OHC Valve Train System
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 53~59
The camshaft locus at camshaft beating in a direct acting OHC valve train system has been investigated using the transient method. Forces applied to the camsfiaft are composed of two components, one is the transfer force between the cam and the tappet, the other is the frictional force. These forces have been calculated using the lumped mass model and the elastohydrodynamic lubrication theory. The alternating direction implicit method has been used for the numerical analysis of Reynolds equation, and 4th order Runge-Kutta method has been used for the transient journal locus analysis. The effects of various load conditions are presented in the form of journal locus. As a result of the analysis, it has been found that camshaft bearings were mainly in the hydrodynamic lubrication condition.
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 60~65
The tungsten disulfide
solid lubricant was synthesized by two different reaction processes, i.e., the reaction between
gas phase and solid
powder, and the vapour phase transport method of tungsten and sulfur in a high vacuum. The chemical and physical characteristics of synthesized
powder were analyzed in terms of the average particle size, morphology, crystalline phase etc. in comparison with those of commercial
powder. The solid
powder with the average size of 0.2
was reacted with
gas flowed with
forming gas for 36 h and 24 h at 90
crystalline phase was then formed through the intermediate phase of .
In the case of vapour phase transport method, the 3.5 wt% iodine was added as a vapour transport reagent into the composition of tungsten and sulfur powders maintaining a constant molar ratio of W:S=1:2.2. The mixture was then heat treated at 85
for 2 weeks in vacuum. The reaction product obtained showed the average size of 12
and the hexagonal plate shape of typical solid lubricant with 2H-
Contact Stress Analysis of the Coating Layer Using Finite Element Method
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 66~70
Thin films and coating technologies are used for an enormous and diverse set of application including mechanical and automotive components. Many of these applications require the various properties which can be used for decreasing wear, friction and cost, and increasing the long life. The relationship between the load and the stress is usually nonlinear. The material is often apt to deform plastically under the low loads. Numerical method may be used for some simple problems of the coating. If the property of coating and base materials are inhomogeneous and the geometry is complex, the numerical method may be recommended. In this paper, the contact normal stress of the coating layer has been solved using finite element method.
The Analysis for Surface Hardening by Repeated Sliding Contact
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 4, 1997, Pages 71~78
Wear is affected by numerous factors-contact load, sliding velocity and distance, friction coefficient, material properties and environmental conditions. Among these wear factors, surface hardness is one of very important factors to determine wear. But surface hardness is varied by work hardening during repeated sliding contact. In this reason wear rate is increased or decreased with varying surface hardness, and transition of wear mechanism is happened. In this study, the surface hardening by accumulating residual stress was analyzed by considering the repeated sliding Hertzian contact model. The results showed that surface hardness was increased with increasing contact load, friction coefficient and contact number. And the depth of hardening layer, plastic layer and elastic layer depended upon contact load and number, but they didn't depend upon friction coefficient. The predicted surface hardness was about 1.5-1.8 times as hard as the material.