• Tribology and Lubricants
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• v.11 no.2
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• pp.24-33
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• 1995

This paper presents the contact stress distributions between the multi-contact bodies and the total reaction forces for various types of contact geometry for multi-load slewing ring bearings. The FEM results indicate that the slope of the roller type of slewing ring bearing has slightly steeper than that of the ball type. This is because the roller type wire race bearings is stiffer than the ball type bearing. The total reaction force of ball type slewing bearing shows much higher than that of wire race slewing bearings.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.179-184
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• 2002

Adhesive contact characteristics of torus-shaped bumps, which are commonly used to reduce friction and stiction in hard disks, are analyzed to examine the applicability to the MEMS structure. The analysis is conducted with the finite element technique considering the adhesive force. Torus-shaped bumps of various rim and bump radii are analyzed. The jump-to-contact behavior, adhesion hysterisis, pull-off forces, contact region and pressure, and surface and subsurface stresses are presented and discussed. Analysis results in the absence of adhesive force are also presented to identify the effect of adhesive force.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1034-1037
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• 2003

Recently in the field of precision positioning device, the contact-free actuators are gaining focuses with their outstanding performances by eliminating mechanical frictions. Th is paper is about the driving algorithm for contact-free linear actuator. The proposed driving algorithm has similar structure of drives of switched reluctance motor and reduces the normal forces and force ripple. The simulation and experiment are executed to verify the proposed method.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.358-364
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• 1999

A wheel/rail contact module for dynamics analysis of railway vehicles is developed. The developed module is based on non-linear contact and FASTSIM algorithm which calculates contact forces. And the module is incorporated into the general purpose program DADS using user-defined subroutines. The simulation results of this developed program is compared to those of the railway vehicle dynamics analysis program AGEM. Since the module is based on DADS, various simulation environments can be considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.780-785
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• 2001

A method for accurate measurement of the contact force in the current collection system of the high-speed railway is developed. In order to measure the contact force with minimal modifications to the pantograph, strain gauges are attached to the bottom of the contact strip. An algorithm for deriving the magnitude and stagger of the contact force from the bending strain measurements is devised. For the sample pantograph, the static contact forces are measured to within ${\pm}$5 % error for the magnitude and ${\pm}$ 2cm error for the stagger. For dynamic contact force measurement, it is found that the contact strip can the regarded as a rigid body for the contact frequency of less than 15 ㎐.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.505-513
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• 2017

In this paper, a receding contact problem for an elastic layer resting on a half plane is considered. The layer is pressed by two rectangular stamps placed symmetrically. 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 is 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 half contact length and contact pressures 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 length and the contact pressures are calculated under various stamp size, stamp position and material properties using both solutions. The analytic results are verified by comparison with finite element results.

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.446-446
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• 2006

• Transactions of Materials Processing
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• v.17 no.7
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• pp.511-516
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• 2008

A drawbead die for the experimental determination of drawbead forces was newly introduced in this paper. While the conventional Nine's drawbead die inevitably includes effects of a blank holding force on the measured drawbead forces, the new drawbead die excludes it by removing the blank holder contact in the dieface. Therefore, the new drawbead die can provide more realistic drawbead forces without considering somewhat arbitrary effect of blank holder with the computational procedure of forming process. The drawbead opening force and restraining force obtained by adopting the two experimental dies were compared for the validation of accuracy in the FEM simulation of automotive fender forming process. The compared section strains and draw-ins confirmed that the present drawbead die provides better drawbead forces for an accurate FEM simulation of sheet metal forming process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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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.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.11 s.188
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• pp.42-49
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• 2006

In this paper error-compensating techniques in three-point weighing method to precisely measure unbalance properties such as center of gravity and unbalance moment. In the conventional static methods, 1) fixture-errors, 2) effects of the contact between the fixture and the load scales, and 3) side effect due to the lateral frictional forces acting on the contact points between the fixture and the load scales are the major factors that lead to measurement errors. The proposed error-compensating method perfectly eliminates both the fixture-error and the contact-error simultaneously by manipulating the three measured reaction forces at three different angular locations. Also the friction-error is calibrated by comparing the sum of three reactions with the actual mass of the specimen. A set of measurement is performed using the same measuring system as Lee's, and a comparison of the results from the convectional, Lee's, and the proposed method is provided. The results show that the proposed method effectively compensates the errors listed above.