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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 18, Issue 6 - Dec 2002
Volume 18, Issue 5 - Oct 2002
Volume 18, Issue 4 - Aug 2002
Volume 18, Issue 3 - Jun 2002
Volume 18, Issue 2 - Apr 2002
Volume 18, Issue 1 - Feb 2002
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Nanotribological Characteristics of Silicon Surfaces Modified by IBAD
Park, Ji-Hyun ; Yang, Seung-Ho ; Kong, Ho-Seung ; Jhang, Kyung-Young ; Yoon, Eui-Sung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 1~8
Nano adhesion and friction between a
AFM(atomic force microscope) tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM and LFM(lateral force microscope) modes in various range of normal loads. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and other Si-wafers of different surface roughness were used. Results showed that nano adhesion and friction decreased with the surface roughness. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the load was low.
A Study on Dynamic Behavior of a Rotor-Bearing System Under External Disturbances
Rho, Byoung-Hoo ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 9~15
The nonlinear vibration characteristics of hydrodynamic journal bearings with a circumferential groove we analyzed numerically when the external sinusoidal disturbances are given to the rotor-bearing system continuously. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film more accurately than the conventional analysis. which uses the Reynolds boundary condition. It is found that the difference between linear and nonlinear analysis is much more remarkable as the amplitude of external disturbance increases, and it depends upon the excitation frequency of the external disturbance. It is also shown that the cavity region in the fluid film increases as the amplitude or excitation frequency of the external disturbance increases. The whirling center of the steady state orbit moves closer to the bearing center as the amplitude or excitation frequency of the external disturbance increases.
The Effect of Compressing ER Electrode on Electrorheological Properties of Anhydrous ER Fluids
Ahn, Byeng-Gil ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 16~23
For increasing the yield stress of ER fluids, the compressing ER electrode was developed and the compressing electrorheological (ER) behavior of anhydrous ER fluids in silicone oil of phosphorous ester cellulose powder was investigated. Under constant electric field, not only the current density but also the yield stress of anhydrous ER fluids were studied as varying the compressing length of ER electrode distance. From the experimental results the compressing of ER electrode had a large influence to the ER properties of anhydrous ER fluids. The current density was proportional to the compressing length of ER electrode under constant electric field and volume fraction also tile compressing yield stress was proportional to the volume fraction of dispersed particles under constant electric field and compressing length. When the ER electrode was compressed with 150mm after charging the electric field, 4 kV, tile yield stress of phosphoric ester cellulose ER fluids increased to thirteen times comparing with the yield stress measured at normal electrode.
Leakage and Rotordynamic Analysis for Staggered-Labyrinth Gas Seal
Ha, Tae-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 24~33
The basic equations are derived for the analysis of a staggered labyrinth gas seal which are generally used in high performance compressors and steam turbines. The Bulk-flow is assumed for a single cavity control volume and the flow is assumed to be completely turbulent in circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about a centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the staggered labyrinth gas seal. Theoretical results of leakage and rotordynamic characteristics for the staggered labyrinth gas seal are compared with those of the plain seal and see-through labyrinth seal.
Finite Element Analysis on the Thermal Behaviors of Non-Contact Type Mechanical Seals Depending on Contacting Face Geometry
Cho, Seung-Hyun ; Kim, Chung-Kyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 34~41
This paper presents the contact thermal behaviors of mechanical seals depending on the contacting face geometry. Using the finite element analysis, the temperature distribution, thermal distortion and leakage have been analyzed as functions of sealing gap and rotating speed of the seal ring shaft. The FE results indicate that the inclined contacting face may be more effective and stable based on the results of thermal characteristic analysis if the seal ring has been designed with a same thermal capacity between conventional rectangular sealing faces and inclined seating surface of seal rings.
An Experimental Study on the Structural Dynanmic Coefficients of Self-Acting Compliant Foil Journal Bearings
Kim, Tae-Ho ; Kim, Chang-Ho ; Lee, Nam-Soo ; Choi, Dong-Hoon ; Lee, Yong-Bok ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 42~48
Experiments were conducted to determine the structural dynamic characteristics of bump foil bearing. The housing of the bearing on the journal was driven by two shakers which were used to simulate dynamic forces acting on the bump foil strips. Three different bump foils(Cu-coated bump, silicon bump, viscoelastic bump) are tested and the dynamic coefficients of three bump foils compared, based on the experimental measurements for a wide range of operating conditions. From the test results, the high damping coefficients of viscoelastic bump are achieved and the possibility of the super-bending-critical operation is suggested.
A Study on the Characteristics of the Compact Hydraulic Servo Mechanism for Proportional Position Control
Lee, Seung-Hyun ; Song, Chang-Seop ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 49~54
In this study, the characteristics of the hydraulic servo mechanism for proportional position control of a hydraulic construction eguipment were analyzed using the developed analysis tool. The result were used in the others hydraulic system except construcdtion eguipment to improve the static performance of the system, the system parameter effects on the controllable region and the hydraulic servo mechanism variation were studied.
Stick-Slip Pressure Variations in a Cylinder of Telescopic Boom
Kim, Shin ; Lee, Hyung-Jik ; Jung, Jae-Youn ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 55~60
In many dynamic systems, there are unwanted oscillation which may arise the reduction of performance. Especially in low sliding speed condition, the stick-slip is an important issue because it because unstable motion as well as inaccurate position control in the system. Most previous works on the stick-slip are, however, only concerned with simple modeling under the condition of constant normal force. The normal force and the amount of hydraulic oil are variable with a cylinder stroke in the telescopic boom. This paper presents the pressure variations during stick-slip with the cylinder of telescope boom. Pressure variations by stick-slip has a similar pattern to that of single mass-spring model. The stick-slip is gradually decreased by means of increased flow rate.
Tribological Characteristics of Surface Modification by Carbon Fiber Reinforced Plastics
Kim, Jong-Hee ; Jeon, Seung-Hong ; Lee, Bong-Goo ; Oh, Seong-Mo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 61~67
The objective of the present study was to investigate the characteristics of the friction and wear according to the amount of ion-irradiation for the carbon fiber reinforced plastic (CFRP). Unidirectional carbon fiber reinforced composites were fabricated with epoxy resin as a matrix and carbon fiber as a reinforcement, and its surface was modified by the ion-assisted reaction. When the amount of ion-irradiation was
. the friction coefficients of composites were about 0.1 and the wear mode was stable. whereas, the friction coefficient of non-treatment composites were about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was
, the friction coefficients were higher rather than that of
Consequently. the amount of ion-irradiation was not in proportion to the friction coefficients, and it was conformed that the optimal conditions would exist between both of them.
A Study on the Dynamic Characteristics of Counter Balance Valve for High Load
Sung, Won-Jun ; Chung, Kwang-Sik ; Lee, Seung-Hyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 1, 2002, Pages 68~74
In this study, the dynamic characteristics of the spool type counter balance valve are studied. The nonlinear governing differential eguations are derived. Routh-Hurwitz criterion is used to characterize the linearized eguations. Static and dynamic experiments are carried out for the determination of parameters that are necessary for the analysis and the stability of the system.