• Title/Summary/Keyword: sliding contact

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A Study on Friction and Wear of TiN Film for the Wear-life Prediction (마모수명평가를 위한 TiN 경질박막의 마찰 및 마모특성에 관한 연구)

  • 정기훈;이영제
    • Tribology and Lubricants
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    • v.13 no.3
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    • pp.28-32
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    • 1997
  • Indentation, scratch and sliding tests were carried out in this paper to predict the critical loads and the failure modes of TiN-coated specimen. The test specimens were S20C steels with three different substrate hardness, roughness and coating thickness. The scratch test shows that the coating thickness has more dominant effect on the critical load of coated disk than the hardness and the roughness. Using the percent contact load, the ratio of sliding load to the critical scratch load, the cycles to failure are measured to predict the wear-life of TiN film. On the wear-life diagram the percent loads and the cycle to failure show the good linear relation on semi-log coordinate. With decreasing loads, the diagram shows the wear-limit at which the coated disk survives more than 4000 cycles.

Experimental Study on Friction Characteristics of Pb-free Pin Bushing for an Internal Combustion Engine (내연기관용 무연 핀부싱의 마찰특성에 관한 실험적 연구)

  • Kim, Chung-Kyun;Oh, Kyoung-Seok
    • Tribology and Lubricants
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    • v.23 no.6
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    • pp.306-311
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    • 2007
  • This paper presents the friction characteristics of pb-fres pin bushing bearings for an automotive gasoline engine. The external load is 100 N to 600 N and the speed of the pin bushing bearing is 1000 rpm to 3000 rpm against the rubbing surfaces. And the contact modes of rubbing surfaces between a piston pin and a pb-free pin bushing specimen are a dry friction, an oil lubricated friction and a mixed friction that is starved by a lack of engine oil. Two influential factors of a contact rubbing modes and a material property are very important parameters on the tribological performance of a friction characteristic between a piston pin and a pb-free pin bushing. The experimental result shows that the pin bushing speed of 2000 rpm shows a typical oil film lubricated sliding contact mode in which means that as the applied load is increased, the friction loss is increasing. But other contact mode depending on the speed and the load may affect to the fiction coefficient without a regular and uniform trend. In summary, the oil lubricated rubbing surface definitely decreases a running-in period in short and increase oil film stiffness, and this may leads the reduction of a friction loss.

Wear assessment of the WC/Co cemented carbidetricone drillbits in an open pit mine

  • Saeidi, Omid;Elyasi, Ayub;Torabi, Seyed Rahman
    • Geomechanics and Engineering
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    • v.8 no.4
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    • pp.477-493
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    • 2015
  • In rock drilling, the most important characteristic to clarify is the wear of the drill bits. The reason that the rock drill bits fail with time is wear. In dry sliding contact adhesive wear deteriorates the materials in contact, quickly, and is the result of shear fracture in the momentary contact joins between the surfaces. This paper aims at presenting an overview of the assessment of WC/Co cemented carbide (CC) tricone bit in rotary drilling. To study wear of these bits, two approaches have been used in this research. Firstly, the new bits were weighted before they mounted on the drill rigs and also after completion their useful life to obtain bit weight loss percentage. The characteristics of the rock types drilled by using such this bit were measured, simultaneously. Alternatively, to measure contact wear, namely, matrix wear a micrometer has been used with a resolution of 0.02 mm at different direction on the tricone bits. Equivalent quartz content (EQC), net quartz content (QC), muscovite content (Mu), coarseness index (CI) of drill cuttings and compressive strength of rocks (UCS) were obtained along with thin sections to investigate mineralogical properties in detail. The correlation between effective parameters and bit wear were obtained as result of this study. It was observed that UCS shows no significant correlation with bit wear. By increasing CI and cutting size of rocks wear of bit increases.

Time-variety Characteristics Analysis of Squeal Noise due to Proposed Wear Model and Experimental Verification (제안된 마모 모델에 따른 스퀼소음의 시변특성 해석과 실험적 검증)

  • Lee, Ho-Gun;Son, Min-Hyuk;Seo, Young-Wook;Boo, Kwang-Seok;Kim, Heung-Seob
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.89-90
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    • 2008
  • This paper studies the effect of pad at initial stage and wear during braking on the dynamic contact pressure distribution. Wear is influenced by variable factor (contact pressure, sliding speed, radius, temperature) during dynamic braking and variation in contact pressure distribution. Many researchers have conducted complex eigenvalue analysis considering wear characteristic with Lim and Ashby wear map. The conventional analysis method is assumed the pad has smooth and flat surfaces. The purpose of this paper is to validate that wear rate induced by braking is considered for the precise squeal prediction. After obtaining pad wear from experiment, it is incorporated with FE model of brake system. Finally, the comparisons in fugitive nature of squeal will be carried out between the complex eigenvalue analysis and noise dynamometer experiment.

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Experimental Study of Dynamic Behavior of a Water Droplet on Diverse Wrinkling Surfaces (마이크로 표면주름 구조에 따른 물방울 동적거동에 관한 실험적 연구)

  • Baek, Dae Hyeon;Zhao, Zhijun;Park, Sang-Hu
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.6
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    • pp.577-585
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    • 2015
  • We fabricated multi-scale such as macro-, micro-, and multi-scale wrinkles by using repetitive volume dividing (RVD) method and thermal curing process. Also wrinkle surface was modified with coating of a self-assembled monolayer (SAM). We measured the contact angle of each wrinkled surface, and observed the behavior of droplets on sloping surface. Through experimental study, we found out that the contact angle was much higher in case of multi-scale and SAM coated wrinkles. And micro-scale wrinkle showed a high contact angle comparing with that of macro-scale wrinkle. Dynamic behaviors of a water droplet like sliding velocity on diverse wrinkled surfaces were dependent on their static contact angles. These results showed that hydro-dynamic characteristics were changed depending on the wrinkle structure and the material forming the wrinkle. These dynamic characteristics can be utilized in bio-chip, microfluidics, and many others in order to control easily chemical reactivity.

Feasibility Study of Friction Characteristics for Impact Analysis (충돌 해석 시 마찰 모델 적용을 위한 기초 마찰 시험 연구)

  • Lee, Kwang-Hee;Lee, Chul-Hee
    • Tribology and Lubricants
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    • v.37 no.3
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    • pp.112-116
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    • 2021
  • Appropriate friction model usage is important for impact analysis because the relative motions between parts that are in contact for very short durations can vary greatly depending on the friction model. Vehicle seat components that have significant effects on impact analysis are also considered. This paper presents an experimental investigation of various material contact pairs to obtain the friction parameters of the Benson exponential friction model for impact simulation. The Coulomb friction model has limitations for impact analysis because of singularity at zero velocity. Metal/nonmetal materials are prepared, and friction tests are conducted for various sliding speeds, loads, and lubrication conditions. The obtained data are used in the friction model to implement finite element analysis. The parameters of the friction model are obtained by the curve-fitting method. The experimental results show that the friction coefficient with metal/nonmetal contact pairs is stable regardless of the working conditions. The friction model used in this study can also be applied for finite element analysis of the crash conditions, where the friction changes abruptly at the contact interface; the obtained friction parameters are also expected to be more accurate with more precise tests under different working conditions. These results can help improve the accuracy of the finite element analysis.

Effect of Wear Environments on the High Stress Sliding Wear Behavior of Ni-base Deloro 50 Alloy (Ni계 Deloro 50합금의 고하중 Sliding 마모거동에 미치는 마모환경의 영향)

  • Choi, Jin-Ho;Choi, Se-Jong;Kim, Jun-Gi;Kim, Yong-Deog;Kim, Hak-Soo;Mun, Ju-Hyun;Baek, Ha-Chung;Lee, Duck-Hyun;Kim, Seon-Jin
    • Korean Journal of Materials Research
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    • v.8 no.12
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    • pp.1115-1120
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    • 1998
  • The sliding wear behavior of Ni-base hardfacing alloy, Deloro 50, was investigated at the contact stresses of 15ksi and 30ksi under the various wear environments. In air at room temperature, Deloro 50 showed lower wear resistance than Stellite 6 even at 15ksi due to the occurrence of severe adhesive wear. This seems to be caused by the lower hardness and work- hardening rate of Deloro 50 than those of Stellite 6. In water at room temperature, Deloro 50 showed as good wear resistance as Stellite 6 at 15ksi. It was considered to be due to that water could effectively prevent metal to metal contact through contacting asperities. However, Deloro 50 showed severe adhesive wear at 30ksi in water at room temperature. It seems to be that the water could not suppress adhesion wear at 30ksi. At $300^{\circ}C$ in air, Deloro 50 exhibited higher wear resistance than Stellite 6 even at 30ksi. It was considered that the oxide glaze layers formed on wear surface during sliding, effectively prevented direct metal-to-metal contacts.

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Effect of load on the wear and friction characteristics of a carbon fiber composites (탄소 섬유 복합재의 마찰 및 마모 특성에 미치는 하중 효과)

  • Koh, Sung-Wi;Yang, Byeong-Chun;Kim, Hyung-Jin;Kim, Jae-Dong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.40 no.4
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    • pp.344-350
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    • 2004
  • This is the study on dry sliding wear behavior of unidirectional carbon fiber reinforced epoxy matrix composite at ambient temperature. The wear rates and friction coefficients against the stainless steel counterpart specularly processed were experimentally determined and the resulting wear mechanisms were microscopically observed. Three principal sliding directions relative to the dominant fiber orientation in the composite wear selected. When sliding took place against smooth and hard counterpart, the highest were resistance and the lowest friction coefficient were observed in the antiparallel direction. When the velocity between the composite and the counterpart went up, the wear rate increased. The fiber destruction and cracking caused fiber bending on the contact surface, which was discovered to be dominant wear mechanism.

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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Experimental Study on Friction Characteristics between Sliding Polymer Plates for Reduction of Stick-and-Slip Abnormal Noise (스틱-슬립음 발생저감을 위한 고분자 소재간 실험적 미끄럼 마찰특성 분석)

  • Lee, Dong-Gyu;Park, Hee-Jin;Park, Sang-Hu
    • Polymer(Korea)
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    • v.37 no.5
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    • pp.642-648
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    • 2013
  • There is a kind of abnormal noise known to come from the stick-slip mechanism induced by frictional impulses during the sliding of two polymeric plates. In this work, quantitative analysis of abnormal noise is carried out based on experimental results. Some combinations of polymer plates, such as an ABS base-plate contacted to ABS, PP, MIPS, and POM plates, which are well-known materials used in home-appliances, are studied to obtain the best combination of polymer plates in order to reduce the abnormal noise. For the experiments, a rig for the test was set up and a methodology was proposed. In addition, the effects of the surface roughness of the plate, the normal loading force, and the relative sliding speed between the two contact plates were evaluated in order to understand the reason for the abnormal noise. Through this experimental work, the optimal combination of materials was ABS/POM system to reduce the noise in real industrial applications.