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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 24, Issue 6 - Dec 2008
Volume 24, Issue 5 - Oct 2008
Volume 24, Issue 4 - Aug 2008
Volume 24, Issue 3 - Jun 2008
Volume 24, Issue 2 - Apr 2008
Volume 24, Issue 1 - Feb 2008
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Tribological Failure Study of Manual Transmissions in Front Engine and Front Wheel Drive Vehicle
Kim, Chung-Kyun ; Lee, Il-Kwon ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 285~290
The purpose of this paper is to present the case study of tribological failure analysis on the gear damages, oil leakage, and sealant sealing in a manual transmission of front engine and front wheel drive vehicle. The manual transmission is to change the speed range and direction of the engines depending on the driving conditions by friction driving forces with input and output gear system. The material property and surface roughness of the gears are strongly related to the gear noise and micro-vibration, oil leakage and wear, which may decrease the real contact area of the gear and the strength of the oil film thickness between the driving gear and driven one. The O-ring damage of speedometer driven gear and bad sealant sealing of oil pan may produce oil leakage through the contact surfaces, which cause the oil shortage and seizure on the sliding surfaces of the transaxle gears. In the failure case study, the proper repair working and good lubrication are very important for the long life of the transaxle without any tribological failures and oil leakage.
Improvement on Prediction of Circumferential-Groove-Pump Seal with CFD Analysis
Ha, Tae-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 291~296
In order to improve the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and circumferentially grooved stator, CFD analysis using FLUENT has been performed to determine the groove penetration angle a which is the angle of separation line between control volumes II and III in groove section of Ha and Lee's three-control-volume theory. Validation to the present analysis using new penetration angle determined by the CFD analysis is achieved by comparisons with the results of published Ha and Lee's analysis. For the leakage prediction the present analysis shows slight improvement and CFD results yields the best. Direct damping and cross-coupled stiffness coefficients are predicted better to the experimental ones. However, direct stiffness coefficient is predicted worse.
Contact Analysis between Rubber Seal, a Spherical Wear Particle and Steel Surface
Park, Tae-Jo ; Yoo, Jae-Chan ; Jo, Hyeon-Dong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 297~301
In many dynamic seals such as lip seal and compression packings, it is well known that wear occur at the surface of heat treated steel shaft as results of the intervened wear particle. It is widely understood that the dominant wear mechanism related in sealing surfaces is abrasive wear. However, little analytical and experimental studies about this problems have been done until now. In this paper, a contact analysis is carried out using MARC to investigate the wear mechanism in contact seal applications considering elastomeric seal, a elastic perfect-plastic micro-spherical particle and steel surface. Deformed seal shapes, contact and von-Mises stress distributions for various particle sizes and interference are showed. The maximum von-Mises stress within steel shaft was exceeded its yield strength and plastic deformation occurred at steel surface. Therefore, the sealing surface can be also worn by sub-surface fatigue due to wear particles together with well known abrasion. The numerical methods and models used in this paper can be applied in design of dynamic sealing systems, and further intensive studies are required.
The Wear Mechanism of Carbon(WC/C) Thin Film in Lubricated Contact
Ahn, Hyo-Sok ; Kim, Doo-In ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 302~307
The running-in behaviour of the metal carbon coating (WC/C) was evaluated with regard to its applicability as wear-resistant coating for key components in engines. Reciprocating wear tests under lubricated condition employing an oscillating friction wear tester were performed to investigate the tribological behaviors of the coatings in ambient environment. Confocal microscopy and scanning electron microscopy were used to observe worn surfaces and the wear scars on the steel balls. Elemental composition of the coating and worn surfaces were characterized using Auger electron spectroscopy. The friction behavior of WC/C coating was comparable to common carbon-based coatings. Thin tribofilm was formed on the worn surface of the steel ball due to material transfer and tribochemical reaction whereas there was no evidence of tribofilm generation on the coating surface. indicating the chemical innertness of WC/C coating.
A Study on Thermal Stress Analysis of Motorcycle Disk Brake
Ryu, Mi-Ra ; Moon, Sung-Dong ; Park, Heung-Sik ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 308~314
The thermal stress have an effect on the frictional factor such as applied load, sliding speed, sliding distance and number of ventilated disk hole. However, it is difficult to know the mutual relation of these factors on thermal stress of motorcycle break disk. For this, temperature of motorcycle break disk is measured using a disk-on-pad type friction tester with full factorial design containing above 4 elements. and the thermal stress analysis of it was carried out using with ANSYS workbench. From this study, the result was shown that the regression equation which have a trust rate of 95% for thermal stress presumption of motorcycle break disk with frictional factor was composed. It is possible to apply for another automobile parts.
Experimental Study on the Interface Bonding Characteristics of a Pin-bushing Bearing
Kim, Chung-Kyun ; Kim, Do-Hyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 315~319
This paper presents the interface bonding characteristics between a phosphor bronze and a steel plate for pin-bush bearings. The pin-bush bearing is an important component in which is used to reduce a friction loss and a wear against the piston pin. The pin-bush bearing is manufactured by hot-pressing a phosphor bronze and a back metal of a steel plate. This paper investigated the bonding interface characteristics in which is manufactured by melting a copper based bronze and a steel plate. The hardness from the inner surface of a bronze to the outer one of steel has been measured using a Vickers hardness tester. The experimental results show that the hardness of a bronze is superior to that of the conventional bronze and the transient hardness of pin-bush bearings is gradually increasing to the hardness of the steel back metal. This means that the bonding interface zone of pin-bush bearings may be fabricated by defusing a bronze to the steel plate due to a density difference between two materials.
Droplet Geometry and Its Volume Analysis
Yoon, Moon-Chul ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 320~325
The recent industrial application requires technical methods to get the cutting fluid droplet surfaces in particular from the viewpoint of topography and micro texture. To characterize the surface topography of droplet, the combination of the confocal laser scanning microscope (CLSM) and wavelet filtering is well suited for obtaining the droplet geometry encountered in tribological research. This technique indicates a better agreement in obtaining an appropriate droplet surface obtained by the CLSM over a detail range of surface accuracy (resolution:
). And the results allow an excellent accuracy in a measurement of a droplet surface. The combination of extended focal depth measurement configured and multi-scale wavelet filtering has proven that it can construct a droplet surface in a successive and accurate way. A multi-scale approach of wavelet filtering was developed based on the decomposition and reconstruction of droplet surface by 2D wavelet transform using db9 (a mother wavelet of daubechies). Also this technique can be extended to characterize the quantification of droplet properties and other field in a wide range of scales. Finally this method is verified to be a better droplet surface modeling in a micro scale arising in a mist machining.
Study on the Enhancement of the Uniform Contact Technology for Large Scale Imprinting with the Design of Vacuum Gripping Pad
Jang, Si-Youl ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 326~331
The contact surfaces between mold and target should be in parallel for a proper imprinting process. However, large size of contacting area makes it difficult for both mating surfaces (mold and target planes) to be in all uniform contact with the expected precision level in terms of thickness and position. This is caused by the waviness of mold and target although it is very small relative to the area scale. The gripping force for both mold and target by the vacuum chuck is other major effect to interrupt the uniform contact, which must be avoided in imprinting mechanism. In this study, the cause of non-conformal contact mechanism between mold and target is investigated with the consideration of deformation due to the vacuum gripping for the size
Experimental Study on the Surface Defects of Scribed Glass Sheets
Kim, Chung-Kyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 332~337
This paper presents the surface defect analysis based on the experimental investigation of scribed glasses. The scribing process by a diamond wheel cutter is widely used as a reliable and inexpensive method for sizing of glass sheets. The wheel cutter generates a small median crack on the glass surface, which is then propagated through the glass thickness for complete separation. The surface contour patterns in which are formed during a scribing process are strongly related to wheel cutter parameters such as wheel tip surface finish, tip angle and wheel diameter, and cutting process parameters such as scribing pressure, speed and tooling technique. The scribed surface of a glass sheet provides normal Wallner lines, which represent regular median cracks and crack propagation in glass thickness, and abnormal surface roughness patterns. In this experimental study, normal and abnormal surface topographic patterns are classified based on the surface defect profiles of scribed glass sheets. A normal surface of a scribed glass sheet shows regular Wallner lines with deep median cracks. But some specimens of scribed glass sheets show that abnormal surface profiles of glass sheets in two pieces are represented by a chipping, irregular surface cracks in depth, edge cracks, and combined crack defects. These surface crack patterns are strongly related to easy breakage of the scribed glass imposed by external forces. Thus the scribed glass with abnormal crack patterns should be removed during a quality control process based on the surface defect classification method as demonstrated in this study.
Slip Coefficients between Steel Plates Fixed with High Tension Bolts
Kim, Choong-Hyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 338~342
Tensile test results using three kinds of steel structure specimens are measured and compared. Slip coefficient between shot blasted steel plates was greater than 0.6. For the case of the plates coated with Super zinc, it revealed that the coefficients were greater than 0.5. On the other hand, Super epoxy coating decreased its slip coefficient less than 0.25. Steel plates coated with Super zinc are proved to be practically applicable to the steel structures with anti-corrosion characteristics and clean surfaces.
Flow Analysis in a Slipper Bearing for Swash Plate Type Axial Piston Pump
Park, Tae-Jo ; Yoo, Jae-Chan ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 343~348
In this paper, a CFD (Computational fluid dynamics) code, FLUENT is adopted to investigate accurate flow characteristics for a slipper bearing which is used swash plate type hydraulic axial piston pump. Static pressure and velocity distributions, and velocity vectors are plotted for different film thickness and slipper rotational velocity. In recess region, there exists a doughnut shaped vortex ring. The static pressure distributions are non-uniform and the flow fields are highly asymmetrical under bearing rotation. Therefore the numerical method adopted in this paper can be use in design of hydrostatic components and further studies are required.
Development of Inter-propellant Seal for High Thrust Turbopump
Kwak, Hyun-D. ; Jeon, Seong-Min ; Kim, Jin-Han ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 349~354
An inter-propellant seal (IPS) for high thrust turbopump is designed. With given operating conditions and requirements, the inter-propellant seal is designed to satisfy the leakage characteristics which is less than 0.1% of normal flow rate of pumps. A numerical analysis is developed to predict the leakage flow rate. The results show that the maximum leakage of LOX and kerosene are less than 0.1% of normal flow rate of pumps, respectively. Based on the numerical analysis results, the detail of IPS is performed. Finally a prototype of IPS is manufactured to perform sets of performance tests in the near future.
Elastohydrodynamic Film Thickness in Elliptical Contacts with Rolling and Spinning
Park, Tae-Jo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 355~361
In highly stressed machine elements such as angular contact ball bearings and toroidal type traction drives, the elastohydrodynamic lubrication of elliptical contacts with both rolling and spinning motion are occur. In this paper, a finite difference method with non-uniform grid systems and the Newton-Raphson method are applied to solve the problems. Pressure distributions, film contours and variations of the minimum and central film thicknesses are compared with various ellipticity parameter, dimensionless speed and load parameter. The results showed that the spinning motion has significant influence especially on the film shapes. Reduction of the minimum film thickness under spinning is remarkable whereas the central film thickness is relatively less. Especially variations of the minimum film thicknesses with rolling velocity, load and ellipticity ratio are a great different from those of pure rolling. Therefore present numerical scheme can be used in the analysis of general elliptical contact EHL problems and further studies are required.
The Influence of Two Phase Flow on Fretting Wear between Steam Generator Tube and Supporting Bar
Lee, Young-Ze ; Park, Jung-Min ; Jeong, Sung-Hoon ; Kim, Jin-Seon ; Park, Se-Min ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 362~367
Tubes in nuclear steam generators are held up by supports because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube-support. The fretting wear of tube-support can threaten the safety of nuclear power plant. The tube and support materials were Inconel 690 and STS 409. The wear tests were conducted in various environments, which are in water without flow, in flowing water and in flowing water with air. The results showed that the flow of water influenced on the wear-life of tube. The wear-life of tube decreased in water flow as compared with wear-life in stationary water.
Friction Characteristics of Hexagonal Array Micro-scale Dimple Pattern by Density
Chae, Young-Hoon ; Jang, Chung-Sun ; Choi, Won-Sik ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 368~373
This paper will investigate the friction characteristics of a 100m Hexagonal Array, Micro-scale Dimple Pattern, on bearing steel. These characteristics are researched by utilizing a pin-on-disk wear test machine, under various test conditions. The reduction of friction is a necessary requirement for the improved efficiency of this machine. As the speed increases, there is a decrease in the effect of the dimple of friction characteristic, with substantially little change to density. Conversely, as the load increases, the dimple pattern grows larger, resulting in a difference in the texture of these two components. At a dimple density of 10% the friction characteristic is easily demonstrated, with a consistent change in both speed and load.
Friction and Wear Characteristics of the Micro-dimple Surfaces in Rotary Compressor with Carbon Dioxide as Refrigerants
Lee, Young-Ze ; Jeon, Hong-Gyu ; Han, Kyu-Cheol ; Choi, Jin-Ho ; Kim, Gyu-Man ; Cho, Sung-Ouk ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 374~377
Due to the environmental concerns, especially the greenhouse effect and GWP (Global Warming Potential), the carbon dioxide was investigated as an alternative natural refrigerant to replace HFCs (HydroFluoroCarbons) in refrigerator or air conditioning systems. Because new compressor with carbon dioxide is going to be operated under the high pressure, the tribology of sliding surfaces in the compressor becomes very important. To improve of wear resistance in compressor parts, especially rotary type, the friction and wear characteristics of improved sliding surfaces between vane and flange were evaluated in this paper. The method of reformed sliding surface, such as micro-dimple processes, was applied on surfaces in order to improve the tribological characteristics, and their performances were evaluated experimentally. The vane-on-flange type lubricated sliding tests were performed with a high pressure wear tester using carbon dioxide. Test results showed that the reformed surfaces were very effective to reduce the friction and the wear amounts of vane surfaces. The method of improved surfaces showed good tribological properties at vane and flange.
The Static Performance Analysis of Foil Journal Bearings Considering Coulomb friction
Kim, Kyung-Woong ; Lee, Dong-Hyun ; Kim, Young-Cheol ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 378~385
In foil bearings, the friction between bumps and their mating surfaces is the major factor which exerts great influence on the bearing performance. From this point of view, many efforts have been made to improve the understanding of the influence of the friction on the foil bearing performance by developing a number of analytical models. However, most of them did not consider the hysteretic behavior of the foil structure resulting from the friction. The present work developed the static structural model in which hysteretic behavior of the friction was considered. The foil structure was modeled using finite element method and the algorithm which determines the conditions of the contact nodes and the directions of the friction forces was used to take into account the friction. The developed model was integrated into the foil bearing prediction code to investigate the effects of the friction on the static performance of the bearing. The results of analysis show that multiple static equilibrium positions are presented for the one static load under the influence of the friction, inferring its great effects on the dynamic performance. However, the effect of friction on the minimum film thickness which determines load capacity of the bearing is negligible.
Friction and Wear Behavior of Coating and Surface Treated Steel for Low Velocity High Pressure Application
Lim, Dong-Phill ; Shim, Dong-Seob ; Kim, Sang-Beom ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 24, issue 6, 2008, Pages 386~392
Friction and wear behavior of hard coated and surface treated steel with candidate processing methods for low velocity high pressure application investigated. Wear tests were carried out under specific region considering the operation condition of construction equipments under lubricated and unlubricated condition. Different tribological behavior analyzed with comparing the wear rate of counter part, morphology and topography of worn surface and the worn volume of samples and counter parts.