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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 25, Issue 6 - Dec 2009
Volume 25, Issue 5 - Oct 2009
Volume 25, Issue 4 - Aug 2009
Volume 25, Issue 3 - Jun 2009
Volume 25, Issue 2 - Apr 2009
Volume 25, Issue 1 - Feb 2009
Selecting the target year
The Limiting Load Capacity of Air Foil Thrust Bearings
Jung, Si-Young ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 279~284
The limiting load capacity of air foil thrust bearings at extremely high operating speeds is theoretically investigated. The limiting load capacity of a sector is shown to increase as the angular extent
and the inlet film thickness
of the bearing increase, while it decreases with an increase in the ramp ratio b and the compliance
of the bearing. But it is found that the angular extent of the bearing is not related to the total limiting load capacity of the
Durability of Phosphorated Starch Based Electrorheological Fluids in Damper Application
Lee, Chul-Hee ; Jang, Min-Gyu ; Sohn, Jung-Woo ; Han, Young-Min ; Choi, Seung-Bok ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 285~291
In this work, durability characteristics of electrorheological (ER) fluid for damper application are experimentally investigated. ER fluid is prepared by using phosphorated starch particles and silicone oil. The field-dependent Bingham characteristics and response time for the proposed ER fluids are experimentally obtained. Experimental apparatus of durability test for ER fluid is established with cylindrical ER cylinder for mid-sized passenger vehicle. In order to evaluate the durability characteristics of ER fluid as a function of time, damping force and temperature variations are measured until one million cycles. After durability test, Bingham characteristics and response time of ER fluid are measured and compared to the initial properties. Microscopic pictures of ER fluid are taken to validate the changes of properties. The results indicate that the ER fluid can be commercially utilized in vehicle damper system with its durability performance. Moreover, the understanding of durability characteristics is essential to predict the service life of ER fluid as well as to design its applications.
A study of the Load Capacity of Air Foil Thrust Bearings
Lee, Yong-Bok ; Kim, Tae-Young ; Park, Dong-Jin ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 292~297
Air foil thrust bearings are the critical components available on high-efficiency turbomachinery which need an ability to endure the large axial force. Air foil bearings are self-acting hydrodynamic bearings that use ambient air as their lubricant. Since the air is squeezed by the edge of compliance-surface of bearing, hydrodynamic force is generated. In this study, we measured the air film thickness and obtained the minimum film thickness experimentally. To increase the maximum load capacity, compliance of sub-structure was controlled. From numerical analyses, it is seen that, if the air film thickness is distributed more uniformly by variable compliance, the thrust bearings can take more axial load.
Leakage Analysis of Angled-Labyrinth-Packing-Ring Seal for Steam Turbine Using CFD
Ha, Tae-Woong ; Kang, Jung-Hyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 298~304
An angled labyrinth seal is used for the diaphragm-packing-ring seal design of steam turbine due to its leakage reduction characteristic. CFD analysis using FLUENT has been performed to predict leakage and determine an optimum slanted angle which yields the best leakage reduction. Results show that the optimum value of slanted angle is
independent of number of labyrinth teeth, inlet pressure, and tooth height to pitch ratio. 3D CFD analysis has been performed for predicting leakage of the angled labyrinth seal. Comparing with the result of 2D CFD analysis, 3D CFD analysis shows 1.4% smaller.
Lubrication Characteristics of Laser Textured Parallel Thrust Bearing: Part 1 - Effect of Dimple Depth
Park, Tae-Jo ; Hwang, Yun-Geon ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 305~310
Laser surface texturing (LST) methods are applied recently to generate micro-dimples in machine components having parallel sliding surfaces such as thrust bearings, mechanical face seals and piston rings, etc. And it is experimentally reported by several researchers that the micro-dimpled bearing surfaces can reduce friction force. Until now, however, theoretical results for various dimple parameters are not fully presented. In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate the effect of dimple depth on the lubrication characteristics of parallel thrust bearing. The results show that the pressure, velocity and density distributions within dimples are highly affected by dimple depths and cavitation conditions. Adoption of micro-dimple on the bearing surface can reduce the friction force highly and its levels are affected by dimple depth. The numerical methods and results can be use in design of optimum dimple characteristics to improve thrust bearing performance.
A Study on Oil Consumption Related with the Piston Ring Pack with Thinner Ring Width and Lower Ring Tension
Chun, Sang-Myung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 311~317
To satisfy the more severe emission regulation and the demand of higher fuel economy in near future, the combustion pressure and power output of engines is going to be higher. In order to get the reduction of engine emission and the higher power, it is needed the reduction of the tension and width of ring pack. The lower tension ring and the thinner width ring can bring not only the friction reduction between the ring and liner during engine running, but also the adjustment of the blow-by gas and oil consumption by changing in the pressure in the crevice volume and the axial motion of rings togethe with the adjustment of the inter-ring crevice volumes. In this study, by using a developed basic computer proglram that predicts the blow-by gas and oil consumption of engines, it is to be examined how satisfying the level of the blow-by gas and oil consumption as being installed the piston ring pack with thinner width ring and lower tension ring.
Experimental Study on the DPF Engine Oil Characteristics Depending on a Mileage of Diesel Automotive
Kim, Chung-Kyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 318~323
The oil characteristics and wear particles of Diesel engines with a DPF have been investigated as a function of a driving distance. The engine oil of SAE 5W30 with ACEA C3 is used for an oil film lubrication of the engine, which is equipped with Diesel particulate filter. Depending on the oil test results, the kinematic viscosity of used engine oils at 40 is degraded up to 5.1% compared with that of unused engine oils, SAE 5W30. And the kinematic viscosity of used engine oils at 100 is more degraded up to 8.1% compared with that of unused engine oils. The oil characteristic as a function of a mileage is not changed depending on the driving distance because of high quality of engine oils. But the aluminum and copper compounds, which are used as base materials of the engine bearing and a pin bush, are much worn and contaminated for the increased mileage of the car. The oil properties of used engine oils are relatively good except phosphorus and calcium additives, which are heavily engaged in the performance of the oils.
A Design Fitness Analysis of Journal Bearings for LPLi Fuel Pump Application
Lee, An-Sung ; Kim, Chang-Up ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 324~329
In this study a complex design fitness analysis of journal bearings is carried out for the LPLi rotary-vane fuel pump application, as an external and horizontal installation, in LPG vehicles. Bearings considered in the analyses are plain and 3-axial groove journal bearings. Upon reflecting the fact that the primary failure mode of bearings in the application is a premature friction and wear failure of bearing metal due to a very low viscosity of liquid fuel LPG as a bearing lubricant, the performance factors of bearings used in an evaluation process of design fitness are a load carrying capacity and vibration suppression ability relative to a rated speed. At this time the design variables of bearings are a radial clearance and length. Results show that, in terms of both of the load carrying capacity and vibration suppression ability, the plain journal bearings are superior to the 3-axial groove journal bearings and among the plain bearings the smaller the bearing clearance (5>10>
) is and the longer the bearing length (6<8<10<12<14 mm) is, the better the bearing performance is.
A Experimental Study on Wear Characteristics of Cu Alloy for Piston Head and Bush Material of Hydraulic Servo Cylinder
Cho, Yon-Sang ; Kim, Young-Hee ; Byon, Sang-Min ; Park, Heung-Sik ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 330~334
Hydraulic servo cylinders have been used to control accurately a large machine in power plant. Especially, Piston head and bush of servo cylinder is assembled sleeve and piston head and bush made of Cu alloy and pad sealing part. A damages of sleeve and piston head, bush are caused by friction and wear. Thus, It is necessary to examine friction and wear characteristics of Cu alloys for the piston head and bush. In this study, to be reliable on the piston and cylinder parts, dry friction and wear experiments were carried out with Cu alloys of four kinds of AlBC, PBC, BC and BS using reciprocating friction tester of pin on disk type. From this study, the result was shown that the AlBC and PBC with alloy elements were excellent to resistance wear. As the sliding speed was increased, the wear loss of PBC decreased than another Cu alloy.
Study on the Film Thickness and Pressure of the Transient Line Contact Elastohydrodynamic Lubrication
Cho, Jae-Cheol ; Jang, Si-Youl ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 335~341
Elastohydrodynamic lubrication (EHL) analysis shows that film thickness is very flat in the contact area and pressure distribution is somehow similar to that of Hertzian contact pressure except the outlet region with pressure spike. These typical patterns of EHL film thickness and pressure are the cases under the steady contact conditions of applied loads and speeds. However, many engineering contacts are rather under the conditions of varying loads and contact speeds, and therefore the predictions for endurance life and performance of machine elements with steady EHL analysis are not suitable in many occasions. This study shows the differences in film thickness formation and pressure distribution between steady and transient contact conditions in several contact cases.
EHL Analysis for Rough Surface with Directional Roughness
Kim, Tae-Wan ; Cho, Yong-Joo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 342~347
This paper presents EHL analysis for rough surfaces with directional roughness. Three different types of surfaces with pure longitudinal roughness, pure transversal roughness and isotropic roughness are generated. For the surfaces with longitudinal and transversal roughness, two cases are analyzed; one is a case of asperity peak on a spherical contact center, the other one is of valley on a spherical contact center. As a results, the surface with pure transversal roughness gives higher pressure and smaller minimum film thickness than the surface with pure longitudinal roughness, and the surface with isotropic roughness has similar EHL behavior with the surface with pure transversal roughness.
A Study on Friction Reduction Related with the Piston Ring Pack with Thinner Width Ring and Lower Tension Ring
Chun, Sang-Myung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 5, 2009, Pages 348~358
To satisfy the more severe emission regulation and the demand of higher fuel economy in near future, the combustion pressure and power output of engines is going to be higher. In order to get the reduction of engine emission and the higher power, it is needed the reduction of the tension and width of ring pack. The lower tension ring and the manufacturing technology of cast iron thinner width ring can bring the friction reduction between the ring and liner during engine running. Therfore, the fuel economy can be achieved. Thereafter the engine emission can be reduced. In this study, by using a developed basic computer program that predicts the inter-ring pressure, the motion of ring and the inter-ring pressure through a crevice volume model between adjacent rings, and the oil film thickness and the friction computed by lubrication theories, it is to be examined the effect of friction reduction from piston ring pack equipped with thinner width ring and lower tension ring.