• 소성∙가공
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• 제7권2호
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• pp.114-126
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• 1998

A plasticity theory applicable to the powdered metal compaction is briefly summarized and its varia-tional form for the finite element analysis is described. The compaction processes of axisymmetric solid cylinder are simulated. For the analysis of the friction effect on compaction process the investigations were performed for different compact geometries. Efforts are focused on the transmitted pressure through the compact and density distributions within the compacts. Numerical results show that :(1) the friction coefficient could be selected simply from the transmitted force data by the single acting compaction test and the simulated results ; and (2) density variations within the compacts rely on the compact geometry such as height to diameter ration and the frictional condition between compact and dies.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1415-1423
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• 2013

The traveling wave ultra-sonic motor (TWUSM) is operated through the frictional force between the rotor and the stator. Hence, the contact mechanism should be analyzed to estimate the motor performance. However, the nonlinearity of the contact mechanism of the TWUSM makes it difficult to propose a proper contact model and a characteristic analysis method. To address these problems, a novel contact model is proposed and be termed the cylindrical dynamic contact model (CDCM) in this research. An estimation method of the motor performance is proposed using the CDCM, an analytical method, and a numerical method. The feasibility and usefulness of the proposed characteristic analysis are verified through experimental data.

• Tribology and Lubricants
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• 제16권2호
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• pp.7-7
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• 2000

Using a coupled thermal-mechanical analysis, the dynamic distortion of the ventilated disk brakes has been presented for a high-speed train. The offset ratio between the maximum and minimum values of the thermal distortions has been analyzed as a function of a braking number. The computed FEM results show that the offset rations in radial direction are much greater than those of circumferentially distorted components. This means that the axial distortions in radial direction may dominantly produce thermally caused wears and cracks at the rubbing surfaces.

• Tribology and Lubricants
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• 제16권2호
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• pp.99-105
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• 2000

Using a coupled thermal-mechanical analysis, the dynamic distortion of the ventilated disk brakes has been presented for a high-speed train. The offset ratio between the maximum and minimum values of the thermal distortions has been analyzed as a function of a braking number. The computed FEM results show that the offset ratios in radial direction are much greater than those of circumferentially distorted components. This means that the axial distortions in radial direction may dominantly produce thermally caused wears and cracks at the rubbing surfaces.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.24-27
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• 2001

Friction between the sheet and tools is one of the important factors affecting the sheet metal forming. Therefore, the clarification of the friction is essential to improve the formability of the sheet. In order to find the effect of material property and lubricant viscosity on the frictional characteristics, tensile test, surface roughness test and friction test are performed. The results showed that friction characteristics are mainly influenced by the surface roughness and lubricant viscosity. A mathematical model of the friction is developed for calculating friction coefficient in terms of surface roughness and lubricant viscosity. The validity and accuracy of the mathematical model of the friction are verified through the experiment and FEM analysis.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.149-158
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• 1998

The thermal deformation of the contact seal components has been analyzed using the finite element method. The temperature distributions, the thermal deformations and contact stresses are solved numerically for the contact surface with wear coning effects. The thermal deformation is always shown to distort the sealing surface along the radius of the seal ring. The results show that the deformations of inner radius side are significant compared with those of outer radius. Thus, the thermal deformation due to thermal heatings may promote the coned face wear or wear related thermal cracks at the contacting face of the seal ring component.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.385-388
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• 2004

The influence of material properties and process parameters on the strain distribution of stamping parts was studied by finite element method. For the parametric study, the investigation of variation of material properties was carried out with tensile test for a dozens of different steel sheets. The friction test for each surface and lubricants conditions are also carried out because the frictional characteristic is important parameter fur sheet metal forming. The geometry of stamping parts was measured by 3D scanner to build the tool model fer the FE analysis. As a result of analysis the major process parameter fer each automotive parts was investigated.

• 대한전기학회논문지
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• 제38권12호
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• pp.1007-1013
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• 1989

This paper describes the procedure of kinmatic design of a quadruped walking machine which has better mobility and higher energy efficiency than the wheeled or tracked vehicles on the rough terrain. Specifically, this paper puts much emphasis on the procedure and its rationality of the design of the leg which is the key mechanical element of the walking robot. And it shows the appropriateness of the selected mechanism and the design method through the walking experiment of the prototype machine built upon the resulted design. The pantograph mechanisms are proved to be acceptable as the leg of the walking machine from the experiment even though it is indicated that the walking speed and the body deflection should be improved further. This paper also describes the problems of the realization of the gait the frictional effects along with their causes in the walking experiment.

• 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.

• 대한기계학회논문집A
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• 제33권12호
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• pp.1357-1365
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• 2009

In this study, we enhance the numerical approach of Lee et al.$^{(1)}$ to spherical indentation technique for property evaluation of hyper-elastic rubber. We first determine the friction coefficient between rubber and indenter in a practical viewpoint. We perform finite element numerical simulations for deeper indentation depth. An optimal data acquisition spot is selected, which features sufficiently large strain energy density and negligible frictional effect. We then improve two normalized functions mapping an indentation load vs. deflection curve into a strain energy density vs. first invariant curve, the latter of which in turn gives the Yeoh-model constants. The enhanced spherical indentation approach produces the rubber material properties with an average error of less than 3%.