• Title/Summary/Keyword: Volume Friction

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A Sensitivity Analysis on Frictional Effect of Backward Impact Extrusion for Rectangular Section Container (직사각형 용기의 후방 충격압출 성형에 대한 마찰의 민감도 해석)

  • 정상원;박승희;김성훈;조규종
    • Transactions of Materials Processing
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    • v.12 no.8
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    • pp.693-701
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    • 2003
  • In this paper, the influence of frictional conditions on the backward impact extrusion of aluminum battery casing with large aspect ratio has been investigated. In the simulation, MSC.Superforge, a package based on the finite volume method, is used for the extrusion analysis. The formability and earing problem during the production have been evaluated by studying the sensitivity to frictional effects. During the sensitivity analysis, the friction factor was varied from 0.02 to 0.24. As the friction factor is increased, the forming height of the narrow edge is decreased, and the forming height of the wide edge is increased. When the friction factor becomes 0.2, the earing problem does not occur The experimental results show a good agreement with analytical results.

Rotordynamic Analysis for Stepped-Labyrinth Gas Seals Using Moodys Friction-Factor Model

  • Ha, Tae-Woong
    • Journal of Mechanical Science and Technology
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    • v.15 no.9
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    • pp.1217-1225
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    • 2001
  • The governing equations are derived for the analysis of a stepped labyrinth gas seal generally used in high performance compressors, gas turbines, and steam turbines. The bulk-flow is assumed for a single cavity control volume set up in a stepped labyrinth cavity and the flow is assumed to be completely turbulent in the circumferential direction. The Moodys wall-friction-factor model is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the stepped labyrinth gas 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 stepped labyrinth gas seal. The resulting leakage and rotordynamic characteristics of the stepped labyrinth gas seal are presented and compared with Scharrers theoretical analysis using Blasius wall-friction-factor model. The present analysis shows a good qualitative agreement of leakage characteristics with Scharrers analysis, but underpredicts by about 20%. For the rotordynamic coefficients, the present analysis generally yields smaller predictied values compared with Scharrers analysis.

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Characteristics of Graphite Particle Size comprised in Metallic Friction Material

  • Kim, Young Gyu;Lee, Jong Seong;Kim, Sang Ho;Lee, Hi Sung
    • International Journal of Railway
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    • v.5 no.4
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    • pp.152-155
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    • 2012
  • The essential element of brake device for railway vehicle is in demand for higher performance along side the trend of railway vehicle size and speed. Essential element of brake device for high speed train is composed of metallic friction material and brake disc. Thus, brake distance, duration and brake stability shall be determined due to friction materials and friction characteristics. Also friction characteristics are influenced by metallic friction material's properties of matter, manufacturing process and component parts. Various materials and configurations of metallic friction materials are currently being implemented to railway vehicles, For this reason study of friction characteristics in accordance with materials is necessary, but study of these important elements are not actively being accomplished. Therefore, in this study, wished to study the graphite's friction characteristic comprised in friction material in accordance with particle size and amount of volume through lab-scale test.

Performance Analysis of Mechanical Face Seal Used for Primary Heat Transport Pump in Heavy Water Reactor (중수로 냉각재 펌프용 미케니컬 페이스 실의 성능 해석)

  • Kim, Jeong-Hun;Kim, Dong-Wook;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.27 no.5
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    • pp.240-248
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    • 2011
  • Mechanical face seal installed in primary heat transport pump used for heavy water reactor prevents leakage of working fluid using thin working fluid film between primary seal ring and mating ring. If the leakage of working fluid exceeds the allowable volume, serious accident can be happened by the trouble of primary heat transport pump. The thinner fluid film exists between primary seal ring and mating ring, the less working fluid leaks out. On the other hand, if the thickness of fluid film is not enough, the life of mechanical face seal will be reduced by friction and wear. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the performance of mechanical face seals which have same deep straight groove and 11 different net coning values. As results, equilibrium clearance between primary seal ring and mating ring, leakage volume of working fluid, friction torque on sealing surface and stiffness of working fluid film were obtained. With increasing net coning value, equilibrium clearance and leakage volume increase, and friction torque and stiffness of fluid film decrease.

An experimental study of the friction and wear on counterpart roughness of silica particle reinforced nano composites (상대재의 거칠기에 따른 실리카 입자강화 나노 복합재료의 마찰 및 마모에 관한 실험적 연구)

  • Kim, Hyung Jin;Lee, Jung-Kyu;Koh, Sung Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.50 no.2
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    • pp.162-168
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    • 2014
  • The friction and wear characteristics of the rubber matrix composites filled with nano sized silica particles were investigated at ambient temperature by pin-on-disc friction test. The volume fraction of silica particles was 19%. The cumulative wear volume and wear rate of these materials on counterpart roughness were determined experimentally. The major failure mechanisms were lapping layers, deformation of matrix, ploughing, debonding of particles, fracture of particles and microcracking by scanning electric microscopy photograph of the tested surface. The cumulative wear volume showed a tendency to increase with increase of sliding distance. The wear rate of these composites tested indicated low value as increasing the sliding distance.

A Study on the Wear Mechanism of the Alumina Ceramics for the Wear of STB2 (베어링 강(STB2)의 마멸에 미치는 알루미나 세라믹스의 마멸기구)

  • Nam, Joon-Woo;Jun, Tae-Ok;Jin, Dong-Kyu
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.3
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    • pp.62-72
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    • 1995
  • The present study was undertaken to investigate the dry wear mechanism of the alumina ceramics in the purity variation for the wear of STB2. The wear test was carried out under different experimental condition various sliding speed, contact pressure and sliding distance. According as the alumina purity increased, wear volume of the STB2 decreased and minimum value of wear volume was over to high speed side. According as the sliding speed and sliding distance increased, friction coefficient decreased owing to drop of the shear strength, it decresed largely owing to decreased of elastic modulus and thermal conductivity with decrease in alumina purity. Indicative of minimum, value of wear volume, low speed side was abrasive wear, high speed side was wear of heat softening. The friction surface of ceramics protacted by oxide was transfer from STB2.

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The Characteristics of Friction and Wear for Automative Leaf Spring Materials (자동차용 Leaf 스프링 재질의 마찰 및 마멸 특성)

  • Oh Se-Doo;Ahn Jong-Chan;Park Soon-Cheol;Jung Won-Wook;Bae Dong-ho;Lee Young-Ze
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2003.11a
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    • pp.118-126
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    • 2003
  • In the present study, the residual stresses can have a significant on the life of structural engineering components. Residual stresses are created by the surface treatment such as shot peening or deep rolling. The objective of this experimental investigation is to study the influence of friction and wear characteristics due to residual stress under dry sliding condition. Friction and wear data were obtained with a specially designed tribometer. Test specimens were made of SUP9(leaf spring material) after they were created residual stress by shot peening treatment. Residual stress profiles were measured at surface by means of the X-ray diffraction. Sliding tests were carried out different contact pressure and same sliding velocity 0.035m/s(50rpm). Leaf spring assembly test used to strain gauge sticked on leaf spring specimen in order to measure interleaf friction of leaf spring. Therefore, we were obtained hysteresis curve. As the residual stresses of surfaces increased, coefficient of friction and wear volume are decreased, but the residual stresses of surfaces are high, and consequently wear volume do not decreased. Coefficient of friction obtained from leaf spring assembly test is lower than that obtained from sliding test. From the results, structural engineering components reduce coefficient of friction and resistant wear in order to have residual stresses themselves.

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Effect of Lubricant with Nanodiamond Particles in Sliding Friction

  • Adzaman, M.H.;Rahman, A.;Lee, Y.Z.;Kim, S.S.
    • Tribology and Lubricants
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    • v.31 no.4
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    • pp.183-188
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    • 2015
  • This paper presents the experimental effects of lubricant with nanodiamond particles in sliding friction. In order to improve the performance of lubricants many additives are used, such as MoS2, cadmium chloride, indium, sulfides, and phosphides. These additives are harmful to human health and to the environment, so alternatives are necessary. One such alternative is nanodiamond powder, which has a large surface area. In order to investigate the effect of nanodiamonds in lubricants under sliding friction, they are dispersed in the lubricant at a variety of concentrations (0 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, and 1 wt%) using the matrix synthesis method. Friction and wear tests are performed according to the ASTM G99 method using a pin-on-disc tester at room temperature. The specimens used in this experiment are AISI 52100 ball bearings and AISI 1020 steel discs. During the test, lubricant mixed with nanodiamond is supplied constantly to keep the two bodies separated by a lubricant film. To maintain boundary lubrication, the speed is set to 0.18 m/s and a load of 294 N is applied to the disc through the pin. Results are recorded by using workbench software over the test duration of 10 minutes. Experimental results show that when the concentration of nanodiamond increases, the coefficient of friction decreases. However, above a nanodiamond concentration of 0.5 wt%, both the coefficient of friction and wear volume increase. From this experiment, the optimum concentration of nanodiamond showing a minimum coefficient of friction of 0.09 and minimum wear volume of 0.82 nm2 was 0.5 wt%.

Behavior on the wear and friction of sealing composite for ship machinery (선박기계용 실링 복합재료의 마모 및 마찰거동)

  • LEE, Jung-Kyu;KOH, Sung Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.53 no.2
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    • pp.204-209
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    • 2017
  • In order to use PUR/CuO Composites as the sealing materials for ships equipment, this research has been performed. PUR/CuO composites are produced by using ultrasonic waves. The increase of CuO leads to increase in the tensile strength and shore hardness. The cumulative wear volume shows a tendency to increase in proportional to sliding distance. As the CuO particles of these composites indicated, the friction coefficient was slightly increased. The major failure mechanisms were lapping layers, deformation of matrix, plowing, debonding of particles and microcracking by scanning electric microscopy photograph of the wear tested surface.

Sliding Friction and Wear Behavior of C/C Composites Against 40 Cr Steel

  • Ge, Yicheng;Yi, Maozhong;Xu, Huijuan;Peng, Ke;Yang, Lin
    • Carbon letters
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    • v.10 no.2
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    • pp.97-100
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    • 2009
  • In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.