• Tribology and Lubricants
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• 제19권2호
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• pp.85-93
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• 2003

In this study, a multigrid multi-integration method has been used to solve the steady-state, elastohydrodynamic lubrication (EHL) point contact problem of a ball joint mechanism used in small reciprocating compressors. Pressure and film thickness profiles have been calculated at minimum and maximum Moes M parameter conditions during one revolution of crankshaft. The effects of various lubricant viscosities, loads, ball velocities, elastic modulli, and radii of curvature on the calculated pressure distribution and film thicknesses have been investigated. The results indicate that the viscosity of lubricant, the sliding velocity of ball, and the reduced radius of curvature have considerable effects on the minimum and central film thicknesses. Solutions obtained with the multigrid analysis are compared with results calculated according to the Hamrock ＆ Dowson relations for the minimum and central film thicknesses.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.385-386
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• 2006

A brake disk in railway vehicle is safety part. Requirements not only in performance but also in comfort, serviceability and working lifetime are high and rising. In this study, we carried out fatigue test and thermal stress analysis. To determine a pressure distribution, contact pressure analysis precede thermal stress analysis. Especially, characteristics of the brake disk were analyzed in considering intial velocity, and thickness of a frictional plate. Form the comparing the results of experiment and FEM analysis, fatigue characteristic and fatigue life assessment ok a brake disk of railway vehicle were performed.

• 한국기계가공학회지
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• 제17권2호
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• pp.37-46
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• 2018

Present research is to evaluate and improve the sealing performance of the duct cap assembly for the ice dispensers through structural analysis. The nonlinear contact problems to check the sealing performance were analyzed using ANSYS software. The results of the analyses related to the sealing performance: the displacement distribution, the contact condition between the cap-silicon and the case, and the pressure distribution on the contact surface, were examined and discussed. Based on the results of the existing design of the duct cap assembly, two cases of the design modifications to improve the sealing performance were introduced. By examining the results of the two cases, a final design improvement plan was proposed and analyzed. It is shown that the sealing performance of the proposed final design is much more favorable than the existing design. The method of structural analysis and design improvement of the duct cap assembly presented in this paper will help improve the sealing performance of the ice dispenser duct caps.

• Structural Engineering and Mechanics
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• 제54권1호
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• pp.69-85
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• 2015

In this paper, a receding contact problem for an elastic layer resting on two quarter planes is considered. The layer is pressed by a stamp and distributed loads. It is assumed that the contact surfaces are frictionless and only compressive traction can be transmitted through the contact surfaces. In addition the effect of body forces are neglected. Firstly, the problem is solved analytically based on theory of elasticity. In this solution, the problem is reduced into a system of singular integral equations in which contact areas and contact stresses are unknowns using boundary conditions and integral transform techniques. This system is solved numerically using Gauss-Jacobi integral formulation. Secondly, two dimensional finite element analysis of the problem is carried out using ANSYS. The dimensionless quantities for the contact areas and the contact pressures are calculated under various distributed load conditions using both solutions. It is concluded that the position and the magnitude of the distributed load have an important role on the contact area and contact pressure distribution between layer and quarter plane contact surface. The analytic results are verified by comparison with finite element results.

• 한국안전학회지
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• 제23권3호
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• pp.25-29
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• 2008

In automotive disc brake system, friction heat is not uniformly distributed due to various reasons such as thermal expansion and imperfections in geometry. It is well known that thermoelastic distortion due to fictional heating affects the contact pressure distribution and can lead to thermoelastic instability, where the contact load is concentrated in one or more small regions on the brake disc surface. These regions then take very high temperatures and passage of hot spots moving under the brake pads can cause low frequency vibration called brake judder. This paper presents the FEM(finite element method) result for the temperature distribution of ventilated disc brake. A steady state two-dimensional model of disc brake system predicts the surface temperatures during a multi-stop driving schedule.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.229-230
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• 2002

This paper presents the hot spot behaviors on the rubbing surface of ventilated disk brake by using finite element method. The depth of asperities on the rubbing surface is usually $2-3\;{\mu}m$ so the real contact area is microscopically. Non-uniform contacts between the disk and the pads lead to high local temperatures, which may cause the material degradation, and develops hot spots, thermal cracking, and brake system failures at the end. High contact asperity flash temperatures in rubbing systems, which is strongly related to the hot spot. It was generally known that high temperature over about $700^{\circ}C$ may form martensite on the cast iron which is material for automotive disk brakes. In this paper, the contact stress, temperature distribution and strain have been presented for the specific asperities of real contact area microscopically by using coupled thermal-mechanical analysis technique.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.405-412
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• 1998

According to the relative stiffness between the half-space and plate or loading condition, some parts of the plate can be separated from the half-space. The finite element procedure to determine the contact area by considering the distribution of contact pressure between plate and the elastic half-space is developed. The vertical surface displacements of the elastic half-space can be obtained through the integrations of the Boussinesq's solution for a point load. The rectangular plate on the elastic half-space is modeled by the 8-node rectangular and 6-node triangular elements and the Mindlin plate theory is used in oder to consider the transverse shear effect. In this study, the contact area may be determined approximately by the analysis with rectangular elements. From this results, the mesh pattern is modified by using triangular and rectangular elements. The contact area can be determined by the new mesh pattern with a relatively sufficient accuracy.

• 한국융합학회논문지
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• 제9권1호
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• pp.283-289
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• 2018

자동차 디스크 브레이크시스템에서는 열유속 및 열변형 등과 같은 이유로 마찰열이 균일하게 분산되지 않는다. 마찰열에 의한 열탄성 변형이 접촉압력 분포에 영향을 미치게 되고, 접촉하중이 디스크 브레이크 표면상의 작은 영역에 집중되어 열탄성 불안정성을 초래 할 수 있다. 본 연구에서는 실험적 계산식과 Kao 제안한 디스크와 패드의 접촉압력에 대한 해석방법을 참고로 하여 3차원 축대칭 모델을 통하여 실제로 제동 시 발생되는 디스크와 패드의 접촉을 고려한 온도해석 및 열변형 해석을 하였다. ANSYS를 사용하여 디스크와 패드의 접촉면에서 발생하는 열탄성 불안전성 문제를 열하중과 기계적 하중으로 동시에 고려하여 해석하였다. 디스크와 패드가 직접 접촉하는 3차원 축대칭 모델을 구성하여 디스크의 마찰면 온도, 열변형, 접촉 열응력을 관찰함으로써 디스크에서 일어나는 열적 거동을 보다 정확하게 관찰하였다.

• 대한기계학회논문집
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• 제13권1호
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• pp.1-8
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• 1989

본 연구에서는 마찰을 무시할 수 있는 경우의 일반적인 다물체 탄성 접촉 문제를 수식화하고 이를 최적화 문제로 변환한 후 수정된 선형 계획법을 이용하여 임의 형상의 다물체간의 접촉 문제를 해석할 수 있는 산법을 제시하였다.

• Design & Manufacturing
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• 제10권1호
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• pp.19-25
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• 2016

Connectors are very important components that transmit electric signals to different parts. It must maintain intensity of the connector to prevent defects from impact and maintain contact to transmit electric signals. Most of the external parts of the connector, which act as the main framework, are formed by injection molding. However, bend deformation occurs for injection molded products due to the residual stress left inside the product after product molding. When the bend deformation is large, it does not come into complete contact when being assembled with other parts, which leads to connector contact intensity not being properly maintained. In result, the main role of the connector, which is to transmit electric signals, cannot be performed. In order to address this problem, this study conducted bend deformation cause analysis through bend deformation analysis to predict and prevent bend deformation of housings and wafers, which are injection molded products of pressure welded connectors that are normally applied in compact mobile and display products. Bend deformation analysis was carried out by checking the charging time, pressure distribution and temperature distribution through wire to board connector wafer and housing injection molding analysis. Based on the results of the bend deformation analysis results, the cause of the bend deformation was analyzed through deformation resulting from disproportional cooling, deformation resulting from disproportional contraction, and deformation resulting from ingredient orientation. In result, it was judged that the effects for bend deformation were biggest due to disproportional contraction for both the pressure welded connector wafer and housing.