• Title/Summary/Keyword: sliding contact

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Life Analysis of Ball Bearings by Accelerated Life Test (가속수명시험을 이용한 볼 베어링 수명분석)

  • 김형의;이윤표;유영철
    • Proceedings of the Korean Reliability Society Conference
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    • 2004.07a
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    • pp.335-342
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    • 2004
  • The failures such as flaking, wear, crack and seizing caused by the high contact pressure accompanied with sliding motion between inner or outer ring and ball are potential failures of ball bearing. In this research, we have qualitatively selected the efficient test items through the analysis of the life and potential failures of ball bearing. The bearing's failures are related closely to the whole system in using the bearing. So, the bearing itself requires an estimation of life in order to opreate the system safely. We have tested ten ball bearings. Our research has applied both radial and axial direction force of maximum torque conditions simultaneously for the accelerated life testing. The result is established by employing the weibull plot and compared the predicted life of ball bearing to the experimental result.

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Development of Graphite Bushing for Bearing (베어링용 흑연재 Bushing 개발)

  • 김경자;조광연;정윤중;임연수
    • Journal of the Korean Ceramic Society
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    • v.34 no.8
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    • pp.797-802
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    • 1997
  • The use of carbon materials in mechanical components such as bearings, seals, and bushings that do not require lubricants is increasing rapidly. This paper reports on establishing the optimal condition for resin-bonded carbon materials. We fixed the content ratio of materials, which include graphite powder and diatomite as a lubricant modifier and a friction modifier, respectably, with resin used as a bonding material. We then produced bushings using hot-pressing within the temperature range of resin curing. The properties of bushing, the friction coefficient, wear rate and the mechanical strengths are discussed in relation to the content of respective materials, with correlation of friction coefficient and sliding distance. Finally, we examined the friction coefficient changes according to the applied load on bushing and the friction coefficient changes according to contact speed of bushing.

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Efficient treatment of rubber friction problems in industrial applications

  • Hofstetter, K.;Eberhardsteiner, J.;Mang, H.A.
    • Structural Engineering and Mechanics
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    • v.22 no.5
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    • pp.517-539
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    • 2006
  • Friction problems involving rubber components are frequently encountered in industrial applications. Their treatment within the framework of numerical simulations by means of the Finite Element Method (FEM) is the main issue of this paper. Special emphasis is placed on the choice of a suitable material model and the formulation of a contact model specially designed for the particular characteristics of rubber friction. A coupled thermomechanical approach allows for consideration of the influence of temperature on the frictional behavior. The developed tools are implemented in the commercial FE code ABAQUS. They are validated taking the sliding motion of a rubber tread block as example. Such simulations are frequently encountered in tire design and development. The simulations are carried out with different formulations for the material and the frictional behavior. Comparison of the obtained results with experimental observations enables to judge the suitability of the applied formulations on a structural scale.

Friction and Wear at Ceramic Coated Surfaces of Aluminum Alloy (알루미늄 합금표면에 코팅된 세라믹재의 마찰마멸 특성)

  • 공호성;권오관;김형선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.12
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    • pp.3083-3093
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    • 1993
  • Friction and wear at ceramic coated surfaces of aluminum alloy were experimentally studied using a Ring-on-Block wear test machine. Ceramic materials coated on aluminum alloy surfaces were WC, CrC, $Al_{2}O_{3}$ by a plasma spray; and $Al_{2}O_{3}$,$Al_{2}SiO_{5}$, $Na_{2}B_{4}O_{7}$,$Na_{4}P_{2}O_{7}$, and $Al_{2}O_{3}-ZrO_{2}$ composite coating by an Anodic Spark Depositon. They were tested under the sliding wet contact and compared with aluminum alloys and steels. Test results showed that ceramic coated surfaces, in general, have better anti-wear property than those of aluminum alloys due to increase in the surface hardness ; however, they also showed higher coefficients of friction and changes in wear mechanisms, resulting in brittle fractures.

The Finite Element Analysis of Foundation Layer by Introducing Interface Element (접합요소를 도입한 기초지반의 유한요소해석(지반공학))

  • 정진섭;이대재;봉기영
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2000.10a
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    • pp.425-430
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    • 2000
  • In the analysis of deformation in which the stiffness is greatly different between the adjacent materials, the desired results have been obtained by using the interface element method compared with those secured by the conventional method of the concept of continua. This study deals with the deformation analysis of soft foundation by the introduction of interface element. The physical conditions of interface element are divided into three categories by Mohr-Coulomb failure criterion ie. sliding, separation, and contact. Finally the accuracy of the program proposed in this paper is proved highly accurate by performing the comparison of the theoretical values numerical results of a model element with simplified boundary conditions.

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The Analysis on Wear Behavior of Cu-$TiB_2$ Composite For Contact Wire (전차선용 Cu-$TiB_2$ 복합재료의 마모거동에 관한 분석)

  • Kim Jung-Nam;Lee Tae-Woo;Kwon Sung-Tae;Kang Kae-Myung
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.704-709
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    • 2004
  • The wear behavior and the mechanical property of Cu-$TiB_2$ composites were examined. Cu-$TiB_2$ composites were fabricated by hot extrusion and cold drawing with $TiB_2$ contents(1$\∼$5vol.$\%$) and the size of $TiB_2$ particles(10$\mu$m and 20$\mu$m). The pin-an-disk wear test was carried out under dry sliding wear conditions which loads varied with from 20N to 100N. At the time, counterpart wear material used SM45C. The experimental results showed that the friction coefficient and wear rate decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle. Also, the depth of plastically deformed zone decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle.

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Reformation of Dielectric Property in interface between epoxy and Cu (Epoxy-Cu간 접촉면에서의 절연특성 개선)

  • 송재주;김성홍;정남성;황종선;한병성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.9-12
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    • 2000
  • Insulators for high-voltage and large-power should be endured mechanically the weight of mold bushing itself and the force of pushed from contact with circuit breaker and conductor. But dielectric breakdown could be occurred result from the external circumstances and internal factors such as chemical reaction, partial discharge, change of temperature and the relation of temperature-time in process of casting. Therefore, to get rid of external and internal factors of dielectric breakdown. Furthermore, to prevent the internal cracks, void, cavity which resulted from the contraction originated on the interface between copper and epoxy resin, formed semi-conductive layer with partially carbon painted on copper bar. The PD properties and the insulation qualities of epoxy molded insulators were improved by roles of cushions for the direction of diameter and natural sliding effects as like separated from conductor for the direction of length.

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Effect of surface hardness on piston wear in the oil hydraulic piston pump (유압 피스톤 펌프의 피스톤 마모에 대한 표면경도의 영향)

  • 김종기;정재연
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.06a
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    • pp.340-345
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    • 2001
  • Surface hardness is one of the major sources on wear in the oil hydraulic axial piston pump. To increase the performance of the oil hydraulic axial piston pump, it is need to know the surface layer characteristics in the sliding contact parts of them. This paper reports an experimental study on surface treatment characteristics in the piston of the oil hydraulic axial piston pump. We investigated surface wear with not only surface hardness and surface roughness but also material of the piston. We obviously observed that the surface hardness of piston in the oil hydraulic axial piston pump plays an important role to high power density and remain long life.

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Effects of Tribological Parameters on the Nonlinear Behavior of a Spur Gear Pair with One-Way Clutch (트라이볼로지 변수가 원웨이클러치를 가지는 평기어쌍의 비선형 거동에 미치는 영향)

  • Cheon, Gill-Jeong
    • Tribology and Lubricants
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    • v.24 no.5
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    • pp.241-249
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    • 2008
  • This paper describes the tribological effects on the nonlinear behavior of a spur gear pair with one-way clutch according to the direct contact elastic deformation model over a wide range of speeds, considering the hydrodynamic effects. The effects of various lubrication parameters, such as viscosity, film width, and friction, on the nonlinear dynamic behavior were analyzed. Forces due to the entraining velocity and the hydrodynamic friction were about two orders smaller than normal forces over the whole speed range. While the viscosity has a strong effect on the behavior of gear pair systems, friction has very little effect on torsional behavior. The inclusion of the hydrodynamic effect facilitates nonlinearity by increasing the overlap and damping, as well as decreasing elastic deformation and tooth reaction forces.

Effect of Surface Roughness on Frictional Behavior of Sheet Steel for Automotive (자동차용 냉연 강판의 표면 거칠기에 따른 마찰 특성 분석)

  • Han, S.S.;Park, K.C.
    • Transactions of Materials Processing
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    • v.17 no.6
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    • pp.401-406
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    • 2008
  • The frictional behavior of stamping process is a function of interface parameters such as sheet and tool material, lubricant, surface roughness, contact pressure, sliding speed etc. Among these parameters the thing that can be controlled by a steel maker is the surface roughness of sheet. In this study, effects of surface roughness on the frictional behavior of steel sheet for automotive were investigated to find out the way to improve the frictional characteristics of steel sheet. The cold rolled steel sheets with various surface roughnesses were prepared for the test. The flat type friction test was conducted with different lubricant conditions. The surface roughness effect on frictional behavior depends on the viscosity of lubricant. The frictional characteristic of steel sheet was influenced by the amplitude of roughness as well as the shape of that.