• Title, Summary, Keyword: sliding contact

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A Study on the surface hardening by repeated sliding contact (반복 미끄럼 접촉에 의한 표면층의 경화에 대한 연구)

  • 박준목;김석삼
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.80-88
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    • 1997
  • Repeated sliding contact wear test was performed with copper specimens to obtain the relationship between wear and surface hardening. Wear surface and wear track section were observed by optical microscopy. Wear volume and micro-vikers hardness of sublayer below wear surface were obtained. These results suggested that wear mechanism depended on contact load than sliding velocity. Therefore wear mechanism was abrasive wear within critical contact load and adhesive wear over critical contact load. Wear rate increased with contact load, sliding distance but decreased with sliding velocity. Surface hardening increased with sliding velocity and sliding distance but decreased with contact load.

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The Analysis for Surface Hardening by Repeated Sliding Contact (반복 미끄럼 접촉에 의한 표면층의 경화에 대한 해석)

  • 박준목;김석삼
    • Tribology and Lubricants
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    • v.13 no.4
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    • pp.71-78
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    • 1997
  • Wear is affected by numerous factors-contact load, sliding velocity and distance, friction coefficient, material properties and environmental conditions. Among these wear factors, surface hardness is one of very important factors to determine wear. But surface hardness is varied by work hardening during repeated sliding contact. In this reason wear rate is increased or decreased with varying surface hardness, and transition of wear mechanism is happened. In this study, the surface hardening by accumulating residual stress was analyzed by considering the repeated sliding Hertzian contact model. The results showed that surface hardness was increased with increasing contact load, friction coefficient and contact number. And the depth of hardening layer, plastic layer and elastic layer depended upon contact load and number, but they didn't depend upon friction coefficient. The predicted surface hardness was about 1.5-1.8 times as hard as the material.

Effects of Combination of the Load and the Apparent Area of Contact on Sliding Wear behavior of Mild Steel in a Pin-on-disc Type Apparatus (Pin-on-Disc식 미끄럼마모시험 시 마모 거동에 미치는 접촉면적 및 하중 조합의 영향)

  • Lee, Han-Young
    • Tribology and Lubricants
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    • v.29 no.2
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    • pp.85-90
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    • 2013
  • The effects of contact pressure on the sliding wear behavior of mild steel in a pin-on-disc type apparatus were investigated. Sliding wear tests were conducted with various combinations of the load and apparent area of contact. The wear behavior of mild steel as a function of sliding speed was independent of contact pressure. However, the wear rate at different sliding speeds was influenced by the load regardless of the apparent area of contact. This was attributed to the fact that there may be no difference in the real area of contact for any combination of the load and apparent area of contact.

Temperature Rise Analysis of Sliding Contact Surfaces in Lubrication Considering Elastic Deformation (탄성변형을 고려한 윤활 상태에서 거친 표면의 미끄럼 접촉온도 해석)

  • Cho Yong-Joo;Kim Byoung-Sun;Lee Sang-Don
    • Tribology and Lubricants
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    • v.22 no.3
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    • pp.137-143
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    • 2006
  • The sliding contact interface of machine components such as bearings, gears frequently operates in lubrication at the inception of sliding failure under high loads, speed and slip. The surface temperature at the interface of bodies in a sliding contact is one of the most important factors influencing the behavior of machine components. Most surface failure in sliding contact region result from frictional heat generation. However, it is difficult to measure temperature rise experimentally. So the calculation of the surface temperature at a sliding contact interface has long been an interesting and important subject for tribologist. The surface temperature rise is related in contact pressure, sliding speed, material properties and lubrication thickness. Though roughness, load, ect all of the condition, are same, film thickness varies with velocity. In this study, surface temperature rise due to frictional heating in lubrication is calculated with various velocities. Surface film shearing and dry solid asperity contact are used to simulate the change of frictional heat in lubricated contact

A Study on Scoring Resistance In Lubricated Sliding Contact (윤활 마찰면의 스코링 저항성에 관한 연구)

  • 김해원;홍재학;허준영
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.2
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    • pp.358-366
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    • 1990
  • As a basic study to clarify the scoring resistance in lubricated sliding contact, the temperature rise on frictional surface was analyzed by theoretical method and the effects of various factors on the temperature rise were examined. On the basic of the results obtained theoretically, the practical equations to calculate the maximum average temperature of the contact surface were proposed which are applicable to sliding contact. Then, the effects of sliding velocity and oil temperature on the seizure behavior, and the relation between seizure and temperature rise were investigated. The following conclusions are deduced : The maximum average temperature rise and the other bulk temperature. The former is affected by the size of heat supply region and the sliding velocity, the latter is affected by heat transfer coefficient. Without regard to the operating condition such as sliding velocity, oil temperature and operating time at each load-step, the maximum average temperature just before seizure is nearly constant except in the region of lower velocity. Consequently, the maximum average temperature of the contact surface in boundary lubrication is a useful criterion to predict the scoring of sliding contact.

A Study for Estimation of the Surface Temperature Rise Using the FVM and Semi-Infinite Solid Analysis (FVM과 반무한체 해석을 이용한 표면온도예측에 관한 연구)

  • 김태완;이상돈;조용주
    • Tribology and Lubricants
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    • v.18 no.6
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    • pp.389-395
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    • 2002
  • The surface temperature at the interface of bodies in a sliding contact is one of the most important factors influencing the behavior of machine components. The calculation of the surface temperature at a sliding contact interface has been an interesting and important subject for tribologist. Temperature analyses were usually performed under the consideration contacted two bodies as semi-infinite. But the analysis was difficulty in being applied to finite body and considering the boundary condition. In this study, contact temperature rise of two finite bodies and surfaces due to frictional heating under the rectangular and the circular sliding contact is calculated. Heat partition factor is calculated using semi-infinite solid analysis and the temperature of the finite bodies is calculated using FVM. It will be shown that Most frictional heat in the fore part of contact region for sliding direction is conducted into body that has a moving heat source and the site of the maximum temperature rise moves to the opposite direction of sliding during sliding.

Relationship between Contact Resistance and Tribological Behavior in Boundary Lubrication (경계윤활에서 접촉 저항과 트라이볼로지 특성의 상관 관계에 관한 연구)

  • 이홍철;김대은
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.76-83
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    • 2000
  • Boundary lubrication condition arises in most lubricated systems, especially during motion reversals and start up phase of operation. In this work electric contact resistance variations with respect to sliding conditions under lubrication is investigated The motivation was to improve the understanding of the contact condition in the boundary lubrication regime. It is shown that electrical contact resistance is sensitive to sliding speed and surface condition of the specimens. Also, phenomena such as run-in during the initial phase of sliding and lubricant pile up near the sliding pin could be observed. The results of this work will aid in better understanding of the metal to metal contact condition in lubricated systems.

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Relationship between Contact Resistance and Tribological Behavior in Boundary Lubrication (경계윤활에서 접촉 저항과 트라이볼로지 특성의 상관 관계에 관한 연구)

  • 이홍철;김대은
    • Tribology and Lubricants
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    • v.16 no.5
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    • pp.381-388
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    • 2000
  • Boundary lubrication condition arises in most lubricated systems, especially during motion reversals and start up phase of operation. In this work electric contact resistance variations with respect to sliding conditions under lubrication is investigated. The motivation was to improve the understanding of the contact condition in the boundary lubrication regime. It is shown that electrical contact resistance is sensitive to sliding speed and surface condition of the specimens. Also, phenomena such as run-in during the initial phase of sliding and lubricant pile up near the sliding pin could be observed. The results of this work will aid in better understanding of the metal to metal contact condition in lubricated systems.

Study of Frictional Behavior of AZ31B Mg Alloy at Elevated Temperature (AZ31B 마그네슘 합금의 온간 마찰 특성 연구)

  • Han, S.S.
    • Transactions of Materials Processing
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    • v.27 no.3
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    • pp.160-164
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    • 2018
  • The success of warm forming of Mg alloy sheets is very dependent on its frictional behavior at elevated temperatures. The effects of contact pressure and sliding length on the frictional characteristics of AZ31B Mg alloy sheet were investigated at elevated temperature and at room temperature. The contact pressure range for the friction test was determined through FE analysis of the roof panel which is a candidate for Mg alloy application. According to the experimental results, the frictional behavior of the Mg alloy sheet is equally highly influenced by both sliding length and contact pressure at room temperature. At elevated temperatures, however, the sliding length has a more dominant influence on the frictional characteristics of the Mg alloy sheet than the contact pressure, if the contact pressure is lower than a certain level.

Finite Element Analysis of Multiple Subsurface Cracks in Half-space Due to Sliding Contact

  • Lee, Sang Yun;Kim, Seock Sam
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.12-16
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    • 2001
  • A finite element analysis of crack propagation in a half-space due to sliding contact was performed. The sliding contact was simulated by a rigid asperity moving across the surface of an elastic half-surface containing single and multiple cracks. Single, coplanar, and parallel cracks were modeled to investigate the interaction effects on the crack growth in contact fatigue. The analysis was based on linear elastic fracture mechanics and the stress intensity factor concept. The crack propagation direction was predicted based on the maximum range of the shear and tensile stress intensity factors.

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