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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 29, Issue 6 - Dec 2013
Volume 29, Issue 5 - Oct 2013
Volume 29, Issue 4 - Aug 2013
Volume 29, Issue 3 - Jun 2013
Volume 29, Issue 2 - Apr 2013
Volume 29, Issue 1 - Feb 2013
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Analysis of the Friction Characteristics of Transmission Clutch of a Wheel Excavator
Lee, Yong Bum ; Kim, Kwang Min ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 1~6
DOI : 10.9725/kstle-2013.29.1.001
Hydraulic transmission is the main component delivering power to the drive wheels of an excavator during forward and backward movement, and it has low speed, high torque and high speed, low torque gear change ratios as a forward/backward two-speed main function. It also has additional function of ensuring that the excavator is stably fixed on the ground with the built-in parking brake during excavation operations. In this study, optimal design specifications are determined by modeling and simulating about the multi-disc-type friction clutch, which is the main component improving the reliability of the hydraulic transmission for a 14-ton wheel excavator, and the friction properties of the transmission clutch are analyzed by performing sample tests.
Modeling & Simulation of a Hydraulic Servo Actuator Cushion for Power Plants
Lee, YongBum ; Yoon, Young Hwan ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 7~12
DOI : 10.9725/kstle-2013.29.1.007
Turbine power control devices at a nuclear / thermoelectric power plant lead to failure by creating mechanical shocks and strong vibrations that are due to the strong elasticity of a spring and the inertia of the valve face during its rapid movement to block steam. To ensure durability of the turbine power control device, which is the main component in the power plant, it is necessary to develop a device that can prevent such vibrations. In this study, a cushion mechanism is added to the head of the hydraulic servo actuator, which is a turbine power control device. Moreover, the cushion mechanism, which includes various modifies shapes and orifices is investigated dynamically through modeling and simulations.
Study on the Load-Carrying Capacity of Finite-Width Slider Bearing with Wavy Surface
Shin, Jung-Hun ; Lee, Gi-Chun ; Park, Jong-Won ; Kang, Bo-Sik ; Kim, Kyung Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 13~18
DOI : 10.9725/kstle-2013.29.1.013
Slider bearing is a widely used load-carrying element in the industry. While a large number of studies have investigated the effect of overall surface curvature, very few have considered sinusoidal surface. Recently, consideration of surface roughness/waviness or intentional wave design has been identified as an important issue in the manufacture of hard disk driver, mechanical seal, hydraulic machine, and etc. This study investigated the load-carrying capacity of a finite-width slider bearing with a wavy surface. Film thickness ratios, length-width ratio, ambient pressure, amplitude, and partial distribution were selected as the simulation parameters. The calculation results showed that the load-carrying capacity rapidly varied at small film thickness ratio, but the waviness near the area of minimum film thickness made much more influence with an increase in film thickness ratio. As the length-width ratio of bearing was increased, ambient pressure became more influential at small film thickness ratios. Furthermore a particular partial distribution of the wavy area led to higher load-carrying capacity than did the whole distribution. Consequently, the results of this study are expected to be of use in surface micro-machining of finite-width slider bearings.
Influence of External Air Velocity for Tribological Characteristics between Sintered Friction Material and Disk
Lee, Jong Seong ; Lee, Hi Sung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 19~26
DOI : 10.9725/kstle-2013.29.1.019
Cu-matrix sintered brake pads and low-alloy heat-resistant steel are commonly applied to basic brake systems in high-energy moving machines. In this research, we analyzed the tribological characteristics to determine the influence of the air velocity between the disk and pad. At a low brake pressure with airflow, the friction stability was decreased as a result of the lack of tribofilm formation at the disk surface. However, there were no significant changes in the friction coefficient under any of the test conditions. The wear rates of the friction materials were decreased with an increase in the airflow velocity. As a result, the airflow velocity influenced the friction stability, as well as the wear rate of the friction materials and disk, but not the friction coefficient.
Effect of Sliding Velocity on 3D Rough Surface in Mixed Lubrication Regime
Lim, DongJin ; Moon, Sukman ; Cho, Yongjoo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 27~32
DOI : 10.9725/kstle-2013.29.1.027
This study examined the effects of surface roughness in the mixed lubrication regime of smooth and rough surfaces for roller bearings. The average flow model was adopted for interaction between the flow rheology of the lubricant and the surface roughness. The average Reynolds equation and related flow factor that describes the coupled effects of surface roughness and flow rheology, the viscosity-pressure and density-pressure equations, the elastic deformation equation, and the force balance equation were solved simultaneously. The results showed that the effects of surface roughness on the film thickness and pressure distribution should be considered, especially in elastohydrodynamic lubrication contact problems.
Load Distribution, Contact and Fatigue Life Analysis of Pitch Bearing for Wind Turbine
Kim, Youngjin ; Moon, Sukman ; Cho, Yongjoo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 33~38
DOI : 10.9725/kstle-2013.29.1.033
This study is aimed to predict the fatigue life for pitch bearings under combined radial, thrust load and moment. In order to do this, a series of simulation such as bearing load distribution, initial surface stress, subsurface stress and fatigue analysis is needd. Fatigue life for pitch bearing can be predicted by using a bearing's material fatigue property.
A Study on the Effect of the Material and Applied Magnetic Field Strength on the Friction Characteristics of Magnetorheological Fluids
Zhang, Peng ; Lee, Kwang-Hee ; Lee, Chul-Hee ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 39~45
DOI : 10.9725/kstle-2013.29.1.039
Magnetorheological (MR) fluid belongs to the group of smart materials. In MR fluid, iron particles in base oil form chains in the direction of the applied magnetic field, thus resulting in a variation in the stiffness and damping characteristics of the fluid. Research is being carried out on controlling the stiffness and damping characteristics as well as the tribological characteristics of the MR fluid. In this study, the friction characteristics of MR fluid have been evaluated using three types of materials and magnetic fields of different strengths. The coefficients of friction of the three types of MR fluid are measured, and the relationship between the coefficient of friction and the strength of the applied magnetic field is obtained.
Effect of Kinematic Motion on Changes in Coefficients of Friction of Porcine Knee Joint Cartilage
Kim, Hwan ; Kim, ChoongYeon ; Lee, KwonYong ; Kim, DaeJoon ; Kim, DoHyung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 46~50
DOI : 10.9725/kstle-2013.29.1.046
In this study, the frictional behaviors of articular cartilage against a Co-Cr alloy in two types of kinematic motions were compared. Cartilage pins were punched from the femoral condyles of porcine knee joints, and Co-Cr alloy disks were machined from orthopedic-grade rods and polished to a surface roughness (
) of 0.002. Friction tests were conducted by using a pin-on-disk-type tribotester in phosphate buffered saline (PBS) under pressures of 0.5, 1, and 2 MPa. All tests were performed in the repeat pass rotational (ROT) and the linear reciprocal (RCP) sliding motions with the same sliding distance and speed of 50 mm/s. The coefficients of friction of the cartilage against the Co-Cr alloy increased with the sliding time in both kinematic motions for all contact pressures. The maximum coefficients of friction in RCP motion were 1.08, 2.82, and 1.96 times those in ROT motion for contact pressures of 0.5, 1, and 2 MPa, respectively. As the contact pressure increased, the coefficients of friction gradually increased in RCP motion, whereas they decrease and then increased in ROT motion. The interaction between the directional change of the shear stress and the orientation of collagen fiber in the superficial layer of the cartilage could affect the change in the frictional behaviors of the cartilage. A large difference in the coefficients of friction between the two kinematic motions could be interpreted as differences in the directional change of shear stress at the contact surface.
Measurement of Electrical Insulating Oil Oxidation by Evaluating the UV Fluorescence Emission Ratio
Wicaksono, Britantyo ; Kong, Hosung ; Han, Hung-Gu ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 29, issue 1, 2013, Pages 51~55
DOI : 10.9725/kstle-2013.29.1.051
In this work, a new fluorescence emission measurement technology was introduced and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate it for the oil oxidation measurement of electrical insulating oil. The oxidation characteristics of insulating oil were found to be fairly represented by the titration method and IR spectroscopy, and the results are comparable to a change in the fluorescence emission ratio that is defined as the shift in fluorescence intensity in the measured wavelength range. The result also shows that by the measurement of fluorescence emission ratio, it is possible to detect the oxidation of oil relatively earlier than by other methods. This study suggests that the developed technology can provide sufficient information for evaluating the insulating oil quality, and that the developed FER sensor can be used as an effective condition monitoring device of electrical insulating oil oxidation.