• Title/Summary/Keyword: Friction Coefficient

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Friction correction for model ship resistance and propulsion tests in ice at NRC's OCRE-RC

  • Lau, Michael
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.3
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    • pp.413-420
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    • 2018
  • This paper documents the result of a preliminary analysis on the influence of hull-ice friction coefficient on model resistance and power predictions and their correlation to full-scale measurements. The study is based on previous model-scale/full-scale correlations performed on the National Research Council - Ocean, Coastal, and River Engineering Research Center's (NRC/OCRE-RC) model test data. There are two objectives for the current study: (1) to validate NRC/OCRE-RC's modeling standards in regarding to its practice of specifying a CFC (Correlation Friction Coefficient) of 0.05 for all its ship models; and (2) to develop a correction methodology for its resistance and propulsion predictions when the model is prepared with an ice friction coefficient slightly deviated from the CFC of 0.05. The mean CFC of 0.056 and 0.050 for perfect correlation as computed from the resistance and power analysis, respectively, have justified NRC/OCRE-RC's selection of 0.05 for the CFC of all its models. Furthermore, a procedure for minor friction corrections is developed.

Tribological Characteristics of Carbon Fiber Reinforced Plastics Prepared by Ion-Assisted Reaction (이온도움반응법에 의한 탄소섬유복합재의 트라이볼로지 특성연구)

  • 오성모;김정기;이봉구
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.4
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    • pp.103-108
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    • 2004
  • Carbon fiber reinforced composites(CFRP) were fabricated with phenolic resin matrix by hot press molding, and its surface was modified by the ion-assisted reaction process. When we tested the friction coefficient and wear rate variation and observed the effect of fibers with respect to friction and wear characteristics, the amount of pitch based carbon fiber was 45wt% and the average friction coefficient was the lowest at 0.12. When the amount of ion-irradiation was $1\times10^{l6}ions/cm^2$, the friction coefficient of the composites was about 0.12 and the wear mode was stable, whereas, the friction coefficient of the non-treated composites was about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5\times10^{l6}ions/cm^2$$1\times10^{l6}ions/cm^2$ion-irradiation case.

A Study of the Friction Characteristics of Plastics on Lubricated Condition (윤활상태에서 플라스틱의 마찰특성에 관한 연구)

  • 강석춘
    • Tribology and Lubricants
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    • v.8 no.1
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    • pp.48-55
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    • 1992
  • The friction characteristic of plastics (PTFE, Nylon, Acetal and phenolic) was studied on the lubricated condition with a pin on disk machine. Mineral oil without additive (base oil) and water were used as liquid lubricants at the controlled temperature. From the experimental work, it was found out that the coefficient of friction of plastics was controlled by the mechanical properities of plastic more than that of liquid for various load and temperature. Viscosity of liquid has affected on the friction only at low temperature under lighb load. Among the tested plastics, the coefficient of friction of PTFE was the lowest under light load and at low temperature while Nylon at medium load and temperature, and Acetal at heavy load and high temperature. The coefficient of friction of soft plastics like PTFE and Nylon were increased as the load and temperature were increased, while that of hard plastic (Acetal) was decreased and that of thermo setting plastic (phenolic) was mixed. Also for soft plastics, the coefficient of friction under heavy load was always higher than that under light load, while hard plastic was vice versa.

Physics of the Coefficient of Friction in CMP

  • Borucki, Len;Philipossian, Ara;Zhuang, Yun
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.2
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    • pp.79-83
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    • 2007
  • The implications of a theory of lubricated pad asperity wafer contact are traced through several fundamental areas of chemical-mechanical polishing. The hypothesized existence of a nanolubrication layer underlies a high accuracy model of polish rates. It also provides a quantitative explanation of a power law relationship between the coefficient of friction and a measure of pad surface flattening. The theory may further be useful for interpreting friction changes during polishing, and may explain why the coefficient of friction is sometimes observed to have a temperature or velocity dependence.

Fundamental study on the effect of friction reduction based micro-scale surface texturing (Micro-scale surface texturing을 기반으로 한 저마찰효과에 대한 기초연구)

  • Chae Younghun;Kim SeockSam
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.17-24
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    • 2004
  • Surrface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

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Friction Characteristics for Density of Micro Dimples Using Photolithography (포토리소그라피를 이용한 마이크로 딤플의 밀도에 따른 마찰 특성)

  • Kim Seock-sam;Chae Young-hun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.3 s.234
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    • pp.411-417
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    • 2005
  • Surface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

Friction Characteristics of Micro-scale Dimple Pattern under Mixed and Hydrodynamic Lubrication Condition (혼합 및 유체윤활하에서 Micro-Scale Dimple Pattern의 마찰특성)

  • Chae Young-Hun;Kim Seock-Sam
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.2
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    • pp.188-193
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    • 2005
  • Surface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

Friction Characteristic of SCM44 Steel using Grease Lubricants (그리스 윤활유의 종류에 따른 SCM44의 마찰특성)

  • Kwon, Soon-Goo;Kwon, Soon-Hong;Kim, Won-Kyung;Choi, Won-Sik
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.6_2
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    • pp.917-926
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    • 2020
  • Friction mechanisms is a very important role in the industrial machinery. However, many experiments have been conducted to reduce the loss of energy resources and parts used due to friction because the friction force adversely affects parts, efficiency, noise, and the like of the power unit. Therefore, in this study, the friction coefficient according to the characteristics of the lubricant was measured to find out which Grease Lubricant maintains the low friction coefficient without being most affected by external conditions. A total of five grease lubricants were tested in this study: GHP CAL 301, GHP EP 2, GHP KG 10, GHP HPG 2, and GHP HTG 2. And the friction coefficient was conducted by changing the load conditions (2, 4, 6, 8, 10N) and rotational speed (24, 48, 67, 86, 105, 124, 143, 162vrpm) using a pin-on-disk wear test system. Also, duty number were calculated. As a result, it was confirmed that in all grease lubricants, the speed did not significantly affect the friction coefficient, and it was confirmed that in all lubricants, the size of the friction coefficient decreased as the load increased from a small load to a large load. In addition, it was determined from the experimental results that GHP EP 2 is the most suitable as a grease lubricant and GHP CAL 301 is not the most suitable.

A Study on Friction Behavior of Textured Surface in Unlubricated State (무윤활 상태에서 미세공이 가공된 표면의 마찰거동에 관한 연구)

  • Oh, Seok-Ju;Kim, Sung-Gi;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.25 no.4
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    • pp.217-224
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    • 2009
  • In this study, friction tests were carried out in order to investigate the friction behavior of textured surface in unlubricated state using ball-on-disk type apparatus. Test specimens were SUJ2 bearing steel ball and SM45C steel disk. Square arrays of circular micro-dimples were created on the surface of disk specimen by Nd:YAG Laser. Friction tests were performed for the disk specimen with various micro-dimple parameters and was also conducted for the variation of normal loads and relative velocities. The results showed that fiction coefficient of textured surface was lower than that of non-textured surface and the deeper depth of micro-dimple was, the lower friction coefficient obtained at the same diameter of micro-dimple in unlubricated state. Area density of micro-dimple had an effect on the friction coefficient. It was also found that friction coefficient generally decreased with the increase of normal load and relative velocity.

Evaluation of Friction Characteristics for High-Strength-Steel Sheets Depending on Conditions (마찰조건에 따른 고강도 강판의 마찰특성 평가)

  • Kim, J. E.;Heo, J. Y.;Yoon, I. C.;Song, J. S.;Youn, K. T.;Park, C. D.
    • Transactions of Materials Processing
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    • v.24 no.6
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    • pp.381-386
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    • 2015
  • Recently, high-strength-steel sheets have been used extensively for increasing fuel-efficiency and stability in automobiles. A study on the characteristics regarding friction factors is required because high-strength-steel sheets have higher contact pressure at the tool interface as compared to low-strength steel sheets. For the current study, a sheet friction test was used to examine the influence of several factors on friction. The friction tests were performed on two types of sheet steels (SPFC590 and SPFC980) to obtain friction coefficients as a function of contact pressure, surface roughness, lubricant viscosity, and speed. Based on the experimental results for SPFC590 and SPFC980, the friction coefficient decreased with increasing contact pressure, but the friction coefficient increased with increasing surface roughness. Also, the friction coefficient decreased with increasing lubricant viscosity and decreasing speed.