• Journal of Astronomy and Space Sciences
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• 제20권2호
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• pp.133-142
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• 2003

접촉쌍성은 물리적 특성에 따라 5가지의 유형으로 분류되고 있다. 그러나 이와 같은 분류 이외에도 질량비가 극단적으로 작은(q＜0.2) 접촉쌍성이 또 다른 유형으로 분류됨을 확인하였다. Svechnikov & Kuznetsova(1990)의 목록에 따르면 이러한 유형의 접촉쌍성은 주성의 분광형이 A형의 한정된 영역에 분포하며 여러 가지 물리적 특성에 있어서 조기형 접촉쌍성과 만기형 접촉쌍성을 양분하는 중심 영역에 분포하고 있다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제25회 춘계학술대회
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• pp.210-217
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• 1997

This paper presents the numerical results of the stress analysis of wheel-rail contact problems. Two models which have straight and tapered(1:20) contact geometries between the wheelset and rail are analyzed using the finite element approach. From the simulation results we found that the tapered geometry of wheel-rail contact base line showed very stable contact stress distributions for a whole contact position between the wheel and rail in a curved rail section. The FEM computed results may present an optimized geometry of wheel-rail contact in a high-speed railway system.

• Tribology and Lubricants
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• 제13권4호
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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.

• Tribology and Lubricants
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• 제29권2호
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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.

• 대한기계학회논문집
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• 제18권6호
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• pp.1559-1566
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• 1994

Using the finite element method, the contact force, contact band width and temperature distribution of lip seals analyzed for the interference including some nonlinearities such as material nonlinearity, geometrical nonlinearity and nonlinear contact boundary condition. The calculated results showed that the contact stress concentrated on the contact zone between the garter spring and the rubber toward the flex side, the contact edge of lip seals. The high contact forces due to the increased interference separate the sealing gap between the lip edge and the rotating shaft. This may lead to leak the sealed oil.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.491-494
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• 2002

To assess the electrostatic interaction of surfaces at the triple contact line, the electrostatic field is analyzed by using the finite element method. The Helmholtz free energy is used as a functional which should be minimized under an equilibrium condition. The numerical results are compared with the nonlinear analytical solution for a two-dimensional charged interface and linear solution for a wedge shaped geometry, which shows fairly good agreement. The method is applied to the analysis of electrostatic influence on the contact angle on a charged substrate. The excess free energy found to increase drastically as the contact angle approaches to zero. This excess free energy Plays an opposite role to the Primary electrocapillary effect, as the contact angle gets smaller. This enables an alternative explanation for the contact-angle saturation phenomenon occurring in electrical control of surface tension and contact angle.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1238-1245
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• 2000

One of the main causes of severe wear or crack initiation in wheel and rail is the contact stress due to wheel-rail contact. First, we obtain contact stress due to the rail mounting slope using the finite element method. Second, the shape design based on more reasonable contact stress analysis rather th~n a general Hertzian contact theory is investigated in order to reduce the contact stress. The optimum -design is performed using the simple 2-D finite element model and its results are verified by 311) finite element analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1361-1366
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• 2008

Failure mechanism of the poor contact is analyzed on the basis of used connectors and this poor contact of connectors is reappeared by the new forced fretting wear method. As the result of failure analysis and reappearance, fretting wear and corrosion of the contact interface causes the contact resistance degradation and the poor contact of connectors. The amount of degradation depends on the fretting stroke. Changes in contact resistance of static contacts are likely to be small and gradual, while motions of contact interface may result in larger and discontinuous changes in resistance and voltage. This voltage drop by fretting motions is large enough to cause the distortion of sensor signal and mis-working of electric components.

• 대한기계학회논문집A
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• 제27권4호
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• pp.544-550
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• 2003

The contact analyses of arbitrary shaped spatial bodies are important in the study of multi-body dynamics. This paper presents a method fur calculating contact force between bodies in space. At each integration time step, the proposed method finds potential contact points on bodies and then calculates the penetration, the velocity of penetration, and the contact force. A continuous analysis method is adopted to calculate the contact force. To get contact points accurately on their outlines, a new algorithm is developed. The proposed algorithm is tested and compared the results of DADS. As applications, the contact of two steel balls, spatial pendulums, and the problem of a ball and bat are demonstrated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1080-1085
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• 2003

The flow of electrical current through a microscopic actual contact spot between two conductors is influenced by the flow through adjacent contact spots. A smoothed version of this interaction effect is developed and used to predict the contact resistance when the statistical size and spatial distribution of contact spots is known. To illustrate the use of the method, an idealized fractal rough surface is defined using the random midpoint displacement algorithm and the size distribution of contact spots is assumed to be given by the intersection of this surface with a constant height plane. With these assumptions, it is shown that including finer scale detail in the fractal surface, equivalent to reducing the sampling length in the measurement of the surface, causes the predicted resistance to approach the perfect contact limit.