• Title/Summary/Keyword: Contact condition

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A study on the performance increasing of current collecting system with a sliding contact (슬라이딩 접촉에 의한 집전시스템의 성능향상의 연구)

  • Jeong, R.G.;Kim, Y.S.;Yoon, Y.Ki.;Park, S.H.;Chung, S.G.;Lee, B.S.;Mok, J.Y.;Choi, S.K.
    • Proceedings of the KIEE Conference
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    • 1999.07a
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    • pp.455-457
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    • 1999
  • In this paper, the wearing characteristics of current collecting shoes, interruption phenomena and contact resistances between collecting shoes and conductor rails are established as design parameters for development of the third rail current collector. An experimental analysis for established design parameters is performed as the materials of current collector shoe, contact force, sliding velocity and contact condition(dry/wet condition) between current collectors shoe and conductor rails. As a result of this study, the magnitude of contact force is in proportion to the amount of wear in the collecting shoe, but is in inverse proportion to the interruption and contact resistance between the collecting shoe and the conductor rail. And optimal values of design parameters are pre sented through analyzing the experimental results of the amount of wear, interruption and contact resistance.

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Measurement of Dynamic Contact Angle of Yarn for Evaluation of Fabric Comfort Performance

  • Hong, Cheol-Jae
    • Science of Emotion and Sensibility
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    • v.5 no.3
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    • pp.67-74
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    • 2002
  • Testing device was newly designed and built to measure the dynamic contact angle. The measurement was made using microscope interfaced with computerized image analysis system while the dynamic condition being controled using Instron. As specimens for the experiment, two different types of fibers, i.e., hydrophilic and hydrophobic, were prepared. In case of hydrophilic fiber, the increase of twist level gave the increase of contact angle. However, in hydrophobic yarn the increase of twist level gave the decrease of contact angle. When saline was used as a telling liquid, the increase of the concentration gave the increase of contact angle. The results rationalized clearly on the basis of known concepts could be used in designing fabric structure for the improvement of comport performance.

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Thin Film Elastohydrodynamic Lubrication of Nanometer Scale (나노미터 크기 유막에서의 탄성유체윤활)

  • 장시열
    • Tribology and Lubricants
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    • v.14 no.1
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    • pp.54-63
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    • 1998
  • In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact has been studied extensively to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

Dynamic Contact Analysis of a Wheel Moving on an Elastic Beam with a High Speed (탄성 보 위를 고속 주행하는 바퀴의 동접촉 해석)

  • Lee, Ki-Su
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.5
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    • pp.541-549
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    • 2008
  • The dynamic contact between a high-speed wheel and an elastic beam is numerically analyzed by solving the whole equations of motion of the wheel and the beam subjected to the contact condition. For the stability of the numerical solution, the velocity and acceleration constraints as well as the displacement constraint are imposed on the contact point. Through the numerical examples, it is shown that the acceleration contact constraint including the Coriolis and centripetal accelerations are crucial for the numerical stability.

접촉결합부를 갖는 원통구조물의 열적,동적 특성 연구

  • 김선민;이선규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.244-249
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    • 1997
  • Internal and external heat sources will cause to deform to machine elements in the contact joint of structure,which results in the change of contact pressure distribution different from initial assembly. Heat induced variations of contact pressure will change the static and dynamic properties such as contact stiffness,damping as well as contact heat conduction in the structure. In order to design and control the intelligent machine tool operating in variant conditions more sophisticatedly, the good prediction for the changes of prescribed propeties are strongly required especially in the contact elements adjacent to the rotational or linear bearing This paper presents some computational and experimental results in regard to static and dynamic characteristics of the press-fitted bush and shaft assembly which is a model of the bearing innerrace and shaft assembly. In the condition of heat generation on the outer surface of the bush,the effects of changes in the negative clearance and the heat flux on pressure distribution and dynamic properties are investigated. Results of this study show that the edge effect of the bush and the initial clearance have effects on the transient dynamic characteristics significantiy.

Thin Film Elastohydrodynamcic Lubrication of Nanometer Scale (나노 미터 크기 유막에서의 탄성유체윤활)

  • 장시열
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1997.10a
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    • pp.173-182
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    • 1997
  • In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact was studied to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

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Study on the Elliptical Elastohydrodynamic Lubrication in the Toroidal Continuously Variable Transmission (가변 동력전달 장치에서의 타원 형상 점접촉 탄성유체윤활 연구)

  • 장시열
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.310-315
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    • 2001
  • The most general feature of contact zone among the mechanical components is elliptical circle. In particular, continuously variable transmission (CVT) of toroidal type has elliptical shape of contact zone under the elastohydrodynamic lubrication condition, where the power is transmitted by the shearing the efluid. Due to the traction of the shear behaviors of lubricant over the small elliptical contact zone, high power of torque is transmitted. During the power transmission, many kinds of mechanical movements occur such as squeezing, sliding, rolling and spinning. The spinning effect that is not common contact behavior in tribological components frequently makes significant abnormal wear damage. In this work, the analysis of elliptical contact of elastohydrodynamic lubrication with spin effect is performed, which will give very useful information to understand the traction behaviors in toroidal type of CVT system.

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Corrosion Behaviors of 316L Stainless Steel Bipolar Plate of PEMFC and Measurements of Interfacial Contact Resistance(ICR) between Gas Diffusion Layer(GDL) and Bipolar Plate (고분자 전해질 연료전지 금속분리판 316L 스테인리스강의 부식거동 및 기체확산층(GDL)과의 계면접촉저항 측정)

  • Oh, In-Hwan;Lee, Jae-Bong
    • Corrosion Science and Technology
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    • v.9 no.3
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    • pp.129-136
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    • 2010
  • The corrosion behaviors of 316L stainless steel were investigated in simulated anodic and cathodic environments for proton exchange membrane fuel cell (PEMFC) by using electrochemical measurement techniques. Interfacial contact resistance(ICR) between the stainless steel and gas diffusion layer(GDL) was also measured. The possibility of 316L was evaluated as a substitute material for the graphite bipolar plate of PEMFC. The value of ICR decreased with an increase in compaction stress(20 N/$cm^2$~220 N/$cm^2$) showing the higher values than the required value in PEMFC condition. Although 316L was spontaneously passivated in simulated cathodic environment, its passive state was unstable in simulated anodic environment. Potentiostatic and electrochemical impedance spectroscopy (EIS) measurement results showed that the corrosion resistance in cathodic condition was higher and more stable than that in anodic condition. Field emission scanning electron microscopy (FE-SEM), and inductively coupled plasma(ICP) were used to analyze the surface morphology and the metal ion concentration in electrolytes.

Effect of Kinetically Processing Conditions on Ink Transfer Ratio for Transfer Printing

  • Park, Sung-Ryool;Kim, Se-Min;Ryu, Gi-Seong;Lee, Chang-Bin;Song, Chung-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.910-913
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    • 2009
  • This paper examines attaching speed, detaching speed and contact time which affected in the ink transfer ratio and presents the best conditions for fabrication process of electrodes with Ag-ink using microcontact printing method. In conclusion, it shows the best printing characteristic by two conditions. One of condition is the attaching speed have to within less than 1mm/s and the detaching speed is high velocity as 1000mm/s and the contact time is taken about the minimum time when inking process. Another condition is the attaching speed have to within more than 100mm/s and the detaching speed have to within less than 1mm/s and the contact time is longer than 30second when the printing process. As using these condition and the stamp sized 5cm${\times}$5cm, it was possible for printing equally until $30{\mu}m$ of width. The printed thickness of a electrode was about 300 to 500 nm, the surface roughness was about dozens nm under 50 nm.

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