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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
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Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 14, Issue 4 - Dec 1998
Volume 14, Issue 3 - Sep 1998
Volume 14, Issue 2 - Jun 1998
Volume 14, Issue 1 - Mar 1998
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Effect of Gamma-Irradiation Sterilization on the Creep and Wear of Ultra-High Molecular Weight Polyethylene
Lee, Kwon-Yong ; Lee, Soo-Cheol ; Lee, Keun-Ho ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 1~6
The Prediction of Scuffing Life due to Plastic Deformation and Low-cycle Fatigue Properties Under Various Lubricated Conditions
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 7~14
A correlation between the low-cycle fatigue life and the scuffing-failure life is demonstrated using the plastic strain increment in boundary lubricated sliding. Loadings proportional to hardness with three different lubricated conditions were used to evaluate the plastic strain increments. As the results of scuffing tests using vacuum pump oils in nitrogen gas, plastic strain increment shows 0.0062, and in the mineral oils and commercial engine oils in air, plastic strain increments show 0.0042 and 0.00092. Those are very useful to describe quantitatively the real lubricated sliding conditions, and are very effective to find the relation between the low-cycle fatigue life and the scuffing-failure life.
A Study on Characteristics of a Compensator System for Swash Plate Type Axial Piston Pump
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 15~22
Recently, the importance of variable displacement piston pump is increasing in industrial world. Especially, most consumers require various range of pressures and flow rates. Pressure compensator is a system controlling flow rate in piston pump at low cost and, therefore, satisfies the need of consumers. However, the system has serious problems, such as response and leakage. The response and leakage are affected by clearance between actuator piston and cylinder, roughness of surface, and spool overlap. In this paper, these effects are investigated experimentally, and optimal clearance and chamfer is obtained. While diameter of cylinder is fixed and diameter of actuator piston is changed in this experiment, response and leakage are measured. Also parameters such as roughness and processing accuracy are changed for piston of fixed clearance. Experimental setup modelled into several parts of actuator piston, cylinder, spool, and swash plate. Input pressure is changed by function generator and proportional valve. The result of this experiment shows that leakage increases very much in proportion to the increase of clearance, and especially leakage occurs enormously when clearance is more than 0.002. The response is not good because as clearance increases leakage increases and as clearance decreases viscous damping effect increases. Accordingly, it is found out that optimal clearance range exists for tile response, within about 0.0012∼0.0014, at this time. Futhermore, the better roughness and geometrical accuracy of actuator piston are, the smaller are leakage and friction. The paper informs that response and leakage are influenced by and geometrical accuracy of actuator piston, roughness of surface, and the clearance between actuator piston and cylinder, and that optimal design of actuator piston in the pressure compensator is possible.
Friction Characteristics between the Cylinder Block and the Spherical Valve Plate in Hydraulic Axial Piston Pump
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 23~28
To increase the efficiency of the hydraulic axial piston pumps, it is need to know the various characteristics in the sliding contact parts of them. Especially, friction characteristics between the cylinder block and the valve plate in the hydraulic axial piston pumps plays an important role to high power density. In this paper, we tried to clarify friction characteristics between the cylinder block and the spherical valve plate in bent-axis-type axial piston pump in experimentally. Results are arranged as follow; (1) friction torque between the cylinder block and the spherical valve plate has a proportional relation to weight or rotational speed, and is strongly affected by temperature. (2) Friction torque strongly depends on force balance ratio in valve plate. (3) In this experiment, lubrication condition between the cylinder block and the spherical valve plate is under hydrodynamic lubrication.
Thermal Stress Characteristics of a Disk Pad in High-Speed Brakes
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 29~36
The thermal characteristics of a disk such as temperature distribution, thermal behaviors and thermal stress during a braking operation has been analyzed for a high-speed brake using the finite element method. The maximum stress for a pad loaded against a disk was occurred at the trailing and leading edges of the disk pad at the underlayer-backplate interface. The FEM results indicate that the thermal characteristics of the spot type pad shows good performance compared with those of the flat type pad. Thus, the spot type pad in brake system may be recommended for the high-speed train system.
Development of Friction Reduction Method between Piston Ring and Cylinder Liner
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 37~43
The friction loss between piston rings and cylinder liner is due to the tension of the piston rings. Lubricant is usually supplied to reduce the friction. However, the sliding speed of the piston varies during the reciprocating cycle and is very low near TDC(Top Dead Center)/BDC(Bottom Dead Center), where the hydrodynamic lubrication cannot be sustained. Since the lubrication regime is shifted from the hydrodynamic to the boundary lubrication near TDC/BDC, wear particles are easily generated so that the friction loss becomes bigger and bigger due to the plowing effect of wear particles. In this study, for the purpose of reducing the friction loss, an undulated surface is adopted to the cylinder liner to trap wear particles. The friction force variations, which are measured by strain gaged, show that the concept of undulated surface is one of the promising methods to effectively reduce the friction between piston rings and cylinder liner.
The Simulation of the Characteristics of the Levitation Force in Superconductor Using 2D Slab Model
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 44~50
This paper describes the simulation of the levitation force between permanent magnet and high Tc(critical temperature) superconductor(HTSC). Levitation force is evaluated numerically on the basis of the magnetic vector potential method and the critical state model. The superconductor is approximated to 2-D slab model. By performing computations, the following characteristics have been investigated: the process of the generation of hysteresis, the various hysteretic behaviors. The characteristics of hysteresis are important for the application to magnetic bearing, for the damping and the nonlinear stiffness is related to hysteresis.
A Study on the Driving of Rods in Hydraulic Bent-axis-type Axial Piston Pump Part 1: The Theoretical Analysis of Driving Mechanism
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 51~57
Recently, bent-axis-type axial piston pumps driven by rods being in extensively used in the world, because of simple design, lightweight, effective cost. So, to guarantee the quality of bent-axis-type axial piston pumps driven by rods, it is necessary to know characteristics of the driving mechanism of rods. But, as they perform both reciprocating and spinning motions, it is difficult to understand driving mechanism. In this paper, I studied the theoretical driving mechanisms of cylinder block driven by rods through geometric method. I found that the cylinder block was driven by one rod in limited area and the driving area was changed by rod's tilting angle and cylinder block's swivel angle.
An Elastohydrodynamic Lubrication of Elliptical Contacts Part I: Direction of Lubricant Entrainment Coincident with the Major Axis of the Hertzian Contact Ellipse
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 58~63
This paper presents a study of the elastohydrodynamic lubrication of elliptical contacts where lubricant entrainment coincides with the major axis of the Hertzian contact ellipse. A finite difference method and the Newton-Raphson method are applied to analyze the problem. Film contours and pressure distributions are compared with the results for lubricant entrainment coincides with the minor axis. Variations of the minimum and central film thicknesses with the radius ratio are also examined. The results showed that the present numerical scheme can be used generally in the analysis of the EHL of elliptical contacts where the lubricant entraining vector did not coincide with either of the principal axis of the conjunction.
Dynamic Characteristics and Experimental Study on the Foil Bearings for High Speed Turbo Machinery
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 64~71
In this study deals with measurement of the vibration amplitudes of rotor-bearing system supported by foil bearing were performed experimentally, and the stability of the system were analyzed by using those results. Considering initial operating friction, compare bearing lubricated with only air and bearing surface lubricated with oil. Analyzing the transient data, the understanding of the characteristics fur startup and shutdown of rotor-bearing system are available and the dynamic characteristics of the system also can be analyzed exactly.
An Experimental Study on Friction and Wear Characteristics of Air Curable
Bonded Films with Polymeric Binder Materials
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 72~78
In this work, the effects of binder materials on the tribological behavior were experimentally evaluated for air curable MoS
bonded film lubricants. The binders tested were basically alkyd and acryl based resins, and also were modified by nitro-cellulose in various weight percentages. Effects on the binder ratio to solid lubricants and the molecular weight of binders were also investigated in all aspects of the tribological behavior. For the tests, LFW-1 and Falex tester were used to measure mainly the endurance life and load carrying capacity of bonded lubricants. Results showed that lubricants of methacrylic resin has the better performance than those of other resins, and also the properties of lubricants both of alkyd and acrylic resins could be improved by modification with nitro-cellulose. It was also shown that the optimum ratio of nitro-cellulose related closely to the binder material and the testing machine.
Morphological Analysis of Wear Particles in the Lubricating Oil with Additives
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 79~87
Morphological analysis of wear particles in the lubricating oil is a very effective and versatile means of lubricant analysis for machine condition monitoring and fault diagnosis. The prospects for determining quantitative information about wear particle morphology have been considerably enhanced by recent developments reported in the application of image processing and analysis techniques. This study was undertaken to investigate the influence of oiliness agent and extreme pressure agent on the shape of wear particles. The wear test was performed under different experimental conditions with stearic acid, dibenzyl disulfide(DBDS) and tricresol phosphate(TCP) in paraffinic base oil. Wear particles characteristics were described using four shape parameters, namely 50% volumetric diameter, aspect, roundness and reflectivity. The results showed that the four shape parameters of wear particles depend on a kind of the additives. This analysis of wear debris with computer image processing techniques is sufficient to distinguish some types of wear debris. The wear volume of three kinds of the specimens are affected by the additives with boundary films.
Fretting Wear Characteristics of Zircaloy-4 Tube in Light Water
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 88~94
The fretting wear characteristics of Zircaloy-4 tube in light water were investigated experimentally. A fretting wear tester was designed to be suitable for this fretting test. This study was focused on the effects due to the combination of normal load, slip amplitude and number of cycles as the main factors of fretting. The results of this study showed that the wear volume increased abruptly at slip amplitude above 100
, which is defined as critical slip amplitude of Zircaloy-4 tube in light water, and that under 160
the wear volume decreased as load increased at the same slip amplitude
Electrorheology of Chitosan Suspension by Conduction Models
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 95~99
The electrorheological (ER) behavior of chitosan suspension in the silicone oil was investigated. Chitosan suspension showed a typical ER response, Bingham flow behavior upon application of an electric field due to the polarizability of the branched amino group of the chitosan particles. The shear yield stress exhibited a linear dependence on the volume fraction of particles and the squared electric field. On the basis of the experimental results, chitosan suspension has been correlated with the conduction models for ER response and found to be an ER fluid.
A Parametric Study on the Characteristics of the Oil-Lubricated Wave Journal Bearing
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 100~107
A new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performance of a hydrodynamic journal bearing. This concept features a wave in bearing surface. Not only straight but also twisted wave journal bearing are investigated numerically. The performances of straight and twisted bearings are compared to a plain journal bearing over a wide range of eccentricity. The bearing load and stability characteristics are dependent on the geometric parameters such as the number of waves, the amplitude and the start point of the wave relative to the applied load direction. The wave journal bearing, especially for the twisted one, offers better stability than the plain journal bearing under all eccentricity and load orientation.
The Effect of Engine Oil Degradation and Piston Top Ring Groove Temperature on Carbon Deposit Formation Part II - The Deposit Formation Characteristics of Diesel Engine
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 108~113
In order to investigate the characteristics of top ring groove deposit formation in diesel engine, engine test and simulation test were performed. From component analysis of used oils sampled from actual running engines, soot content in engine oil was selected as a main parameter for evaluating oil degradation. Deposit formation is highly related to soot content in lubricating oils. And high soot content oil accelerates deposit formation even in low temperature region below 26
. In low temperature region below 26
, deposit formation rate is mainly affected by top ring groove temperature. However, in high temperature region above 26
, deposit formation rate is affected by soot content as well as top ring groove temperature. Therefore, soot content as well as top ring groove temperature should be kept a certain level in order to prevent troubles due to carbon deposit formation.
T-curve, wear and Erosion of Silicon Carbide
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 114~120
The T-curve, wear and erosion behaviors of two different silicon carbides, i.e., the fine grained SiC and the in situ-toughened SiC(IST-SiC). Both materials exhibited an increasing T-curve behavior, although the T-curve of IST-SiC was steeper than that of fine grained SiC. The fracture toughness of IST-SiC was larger than that of fine grained SiC at long crack regime, whereas an opposite tendency occurred at short crack regime. The rate of material removal during wear and erosion tests was higher in IST-SiC compared to fine grained SiC. The difference between the material removal rates of two materials was discussed in the light of their R-curve behaviors.
Analysis of Hertzian Contact using East Fourier Transform
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 14, issue 4, 1998, Pages 121~127
In this study, a numerical procedure to solve a contact problem has been developed. The procedure takes advantage of signal processing technique in frequency domain to achieve shorter computing time. Boussinesq's equation was adopted as the response function. This procedure is applicable to a non-periodic surface profile as well as a periodic one. The validity of this procedure has been established by comparing the numerical results with the exact solutions. The fastness of this procedure was shown in comparison with other algorithm.