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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
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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
Selecting the target year
항공용 가스터빈 엔진에서의 트라이볼로지
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 1~9
Study of Friction Charactedstics of Non-asbestos Organic (NAO) and Semi-metallic Brake Pads During Automotive Braking
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 10~19
Frictional characteristics of two different types of automotive friction materials were studied. They were non-asbestos organic and semi-metallic friction materials. The two friction materials were tested using an inertial brake dynamometer to investigate friction stability, rooster tailing phenomena, temperature change during drags and stops. Results show that the level of the friction force is strong functions of time, temperature, and speed regardless of the type of friction materials. In particular, rooster tailing effects are pronounced in the case of semi-metallic friction materials compared to non-asbestos organic friction materials. The phenomena appear strongly dependent on raw materials contained in the friction materials.
Evaluation of the Tribological Behavior for
Bonded Films with Different Contact Geometry
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 20~27
The tribological behavior for
bonded films is evaluated according to the international standard testing methods, such as ASTM D 2625 (Falex tester) and ASTM D 2714 (LFW1 tester). It has been well known that the tribological behavior for
bonded films is affected by several factors. However, in this work, the wear life for
bonded films is mainly experimentally measured with different contact geometry, and evaluated in terms of the frictional heating according to the contact geometry of tribotester. The test results show that the wear life of
bonded films is significantly affected not only by the frictional heating, but also by the contact pressure, test running-in conditions, and the contact conformity.
A Study on Friction and Wear of TiN Film for the Wear-life Prediction
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 28~32
Indentation, scratch and sliding tests were carried out in this paper to predict the critical loads and the failure modes of TiN-coated specimen. The test specimens were S20C steels with three different substrate hardness, roughness and coating thickness. The scratch test shows that the coating thickness has more dominant effect on the critical load of coated disk than the hardness and the roughness. Using the percent contact load, the ratio of sliding load to the critical scratch load, the cycles to failure are measured to predict the wear-life of TiN film. On the wear-life diagram the percent loads and the cycle to failure show the good linear relation on semi-log coordinate. With decreasing loads, the diagram shows the wear-limit at which the coated disk survives more than 4000 cycles.
An Analysis of Dynamic Characteristics of Tilling Pad Thrust Bearings
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 33~41
In this paper the linearized stiffness and damping coefficients of tilting pad thrust bearing are calculated by the perturbation method. The coefficients are obtained for a wide range of pivot positions. The effects of exciting frequency and pad mass on stiffness and damping coefficients are investigated. Critical frequencies due to the tilting motions of the pad are presented and are shown to be strongly influenced by the pivot position and the pad mass.
A Study on Erosion Properties of Hot Pressed Sialon Ceramics
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 42~47
Three kinds of the sialon ceramics with and without TiN additions were prepared by hot pressing to investigate the effect of microstructure on erosion behaviors. Hardness and fracture toughness were measured with prepared specimens to study the effect of additives on the mechanical properties. A gas blast type erosion tester was employed to examine erosion behavior of the specimens up to
. Erosion tests showed an increase of erosion rate up to 40
and a gradual decrease of erosion rate up to 50
for all kinds of sialon. The results also showed that erosion rates of the sialons were controlled better by microstructural factors than by mechanical properties including fracture toughness and hardness.
Analysis and Fatigue Life Evaluation of the Ball Bearing with Thin-Section Raceways
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 48~55
The ball bearing with thin-section raceways which is much lighter than other conventional bearings used in most modem passenger cars and small tracks. The important design parameters of this bearing is the groove radius of raceways, the diametral clearance, the free contact angle and so on. The optimal value of these parameters were determined by considering the dynamic load capacity, the contact angle and the calculated fatigue life. The contact angle between a ball and raceways was calculated by considering the local contact deformation and the structural deformation of thin-section raceways which was estimated by FEM. The raceways were made by means of the press-forming process. The fatigue life tester was designed and manufactured. The fatigue life test was executed and the reliability of this bearing was confirmed.
A study on Geometry of Labyrinth Seal for High Speed Machining Center
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 56~62
Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindles require non-contact type sealing mechanism. In this study, an optimum seal design to minimize leakage is concerned in the aspect of flow control. This paper categorizes geometries of mostly used non-contact type seals and analyzes each leakage characteristics to minimize a leakage on sealing area. Effect of minimum clearance and its position are considered according to variation of detail geometry. The estimation of non-leaking property is determined by amount of pressure drop in the leakage path assuming constant leakage flow. To simulate an oil jet or oil mist type high speed spindle lubrication, the working fluid is regarded as two phases that are mixed flow of oil phase and air phase. Both of the turbulence and the compressible flow model were introduced in CFD(Computational Fluid Dynamics) analysis. Design parameters has been induced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted.
A Numerical Analysis on the Rotordynamic Characteristics of a Hybrid Journal Bearing with Pair-Type Angled Injection Orifices
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 63~72
The stability of a rotor-bearing system supported by swirl-controlled hybrid journal bearing with pair-type angled injection orifices is investigated for improvement of the whirl frequency ratio by allowing effective control of the tangential flow inside the bearing clearance, i.e., by achieving more freedom in controlling strength and direction of the supply tangential flow inside the bearing clearance. It is suggested that the system instability can be improved through the change of bearing dynamic characteristic parameters with the swirl control. The orifice diameter
and recess injection angle
along with combinations of swirl/anti-swirl supply pressures and directions (3.0~3.0 MPa, 4.0~2.0 MPa, 2.0~4.0 MPa) are selected for design parameters for swirl-controlled effective factors dependent on journal speeds (3000, 9000, 15000, 21000 rpm). It has been found that the orifice diameter
shows strong effects on effective maneuverability of direct-stiffness and direct damping values, while recess injection angle
results in substantial effects on the magnitude and direction of cross-stiffness. Specifically, recess injection parameters which are functions of angle of orifice feeding flow and recess dimensions showed very feasible effect on the stability control of swirl-controlled rotor-bearing system.
Power Transmission Mechanism of Electrorheological Clutch (Part II: Estimation of Performance Variation due to Temperature Rise of Eiectrorheological Fluid)
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 73~84
ER clutch is a device using ER fluid, so called "intelligent material" and is a controlled system with electric field strength. Currently, the temperature of ER fluid increases and affects the performance of ER clutch when ER clutch is operating. This study was undertaken to estimate this performance variation due to temperature rise of ER fluid. An analytic heat transfer model of concentric cylinder type ER clutch was developed and with this model, effects of changing geometric, kinetic parameters of ER clutch and ER fluid properties were described. In conclusion, compared with neglecting thermal effects, a performance of ER clutch was very differential and for uniform performance of ER clutch, we have to improve thermal stability of ER fluid. ER fluid.
An Experimental Study on the Rolling Resistance of Bearing Surfaces Covered by Pure Silver Film
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 85~92
An experimental study was performed to discover the tribological behaviors of pure silver coated 52100 bearing steel. Pure silver coatings ranging from 80 nm to several micrometers were produced by a thermal evaporation coating method. Experiments using a thrust ball bearing-typed rolling test-rig were performed for the investigations of the influence of coating thickness on the tribological rolling behavior. The existence of optimum film thickness which revealed minimum rolling resistance was discovered. A careful analysis on the contact surfaces for the optimum film thickness has been performed. The contact patches produced by the transferred silver films played an important role for the rolling resistance to keep low.
Finite Element Analysis on the Stress Distributions in Rail-Wheel Contacts of High Speed Trains
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 93~101
The numerical results on the stress distributions of rail-wheel contact problems are presented for three models in a high-speed rail system. These models which have straight and tapered (1:40 and 1:20) contact geometries between the wheelset and rail are analyzed using the finite element approach. From the simulation results we found that the tapered geometry (1:20) of railwheel contact base line showed very stable contact stress distributions for a whole contact position between the wheel and rail in a curved rail section. The FEM computed results may present an optimized slope geometry of rail-wheel contact in a high-speed railway system.
Effect of Ti Coated Diamond Grit on Performance of Diamond Tool
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 102~107
Diamond grit was coated with Ti by RF Sputtering to investigate the effect of coated diamond particles on performance of diamond impregnated saw. Coated and uncoated powders were separately mixed with 70Co-30W powders by conventional milling technique. Hot pressing was carried out to make specimens. The wear test were carried out with these two types of diamond impregnated specimens. It was demonstrated that Ti coating was effective in improving the ability of grit retention and thus enhanced the tribological performance of diamond tool.
Friction and Electrical Characteristics of Oil-impregnated Sintered-Metal Bearing with Grooves
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 108~114
The electrical and frictional properties of new sintered-metal bearing (S-bearing) with varying loads and speeds were measured. Also those were compared with the same products(J-bearing) made in Japan and the conventionally used ball bearing. The test results show that the frictional values of S-bearing are less than those of J-bearing, and that S-bearing operates in full-hydrodynamic lubrication regime. The values of rating current, starting time and jitter reveal that S-bearing is superior to J-bearing as well as ball bearing.
Electrorheological Properties of Water Activated Silica Gel Suspensions
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 13, issue 3, 1997, Pages 115~123
The electrorheological (ER) behavior of suspensions in silicone oil of silica gel powder (average particle size 49
m) absorbed water was investigated at room temperature with electric fields up to 2.4 KV/mm. In this paper, for development of succcessful ER fluids used for wide temperature range later, we would like to know a fundamental understanding of water on ER effect. As a first step, the ER fluids involving water activated silica gel were measured not only the electrical characteristics such as dielectric constant, current density and electrical conductivity but also the rheological properties on the strength of electric field, the quantity of dispersed phase and absorbed water. From the experimental results that water absorbed to the particles directly affects to the surface charge density of electric double layer model proposed by Schwarz and makes dielectric constant and current density of ER fluids increase. The current density and dynamic yield stress $(
_y)$ of water activated silica gel suspensions was in exponential proportion to the strength of electric field, the quantity of dispersed phase and absorbed water. And the optimum water quantity and weight concentration of silica gel for electrorheological effect were 4-5 wt% and 15 wt%, respectively.