• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.52-63
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• 1983

The purpose of the study is to find development of contact area, contact pressure and friction forces occurring at joints or connection areas inbetween structural members or mechanical parts. The problem has a pair of difficulties intrinsically; a constraint of displacement due to contact, and presence of work term by nonconservative friction force in the variational principle of the problem. Because of these difficulties, the variational principle remains in the form of inequality. It is resolved by penalty method and perturbation method making the inequality to an equality which is proper for computational purposes. A contact problem without friction is solved to find contact area and contact pressure, which are to be used as data for the analysis of the friction problem using perturbed variational principle. For numerical experiments, a Hertz problem, a rigid punch problem, and the latter one with friction effects are solved using $Q_2$-finite elements.

• Tribology and Lubricants
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• v.24 no.2
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• pp.90-95
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• 2008

An elastic-plastic contact analysis is developed using a semi-analytical method. The elastic contact is solved within a Hertz theorem. The reciprocal theorem with initial strains is then introduced, to express the surface geometry as a function of contact stress and plastic strains. The irreversible nature of plasticity leads to an incremental formulation of the elastic-plastic contact problem, and an algorithm to solve this problem is set up. Closed form expression, which give residual stresses and surface displacements from plastic strains, are obtained by integration of the reciprocal theorem. The distribution of contact stress, residual stress and plastic strain are obtained by the changed surface geometry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.138-143
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• 2000

In order to maintain the faith and accuracy with precision of machinery, it is recently required the precise comprehension about approach which is appeared in the contact area between two bodies, because approach affects the static stiffness and dynamic characteristic of contact area. This study applied H. Hertz's circle contact area theory as much lower measuring force. It is measured approach influenced by various factors which were concerned with contact errors like material, form of two bodies, using calibration tester. As a result, the following conclusion can be obtained. 1) The approach appears greatly in order of carbon steel(SM20C), aluminum(A601-T6) and high density polyethylene(5305E) 2) The approach appears in order of concave, disc, convex form, in the ration of contact area size by the difference of curvature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.447-448
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.195-196
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.777-778
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• 2008

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.7
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• pp.275-286
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• 2001

The research presents an analytical theory to calculate the characteristics of the bal bearing with waviness in its rolling elements considering the centrifugal force and gyroscopic moment of bal. The effects of centrifugal force and gyroscopic moment are introduced to the kinematic constraints and force equilibrium equations. and the waviness of rolling elements is modeled by sinusoidal function to calculate the contact force at each ball. The numerical solutions of governing equation of berating due to waviness are calculated by using the Newton-Raphson method. The accuracy of the research is validated by comparing the contact force. contact angle in case of considering the centrifugal force and gyroscopic moment of bal and the contact force and vibration frequencies in cases of considering waviness with the prior researches respectively. It investigates the stiffness, contact force. displacement and vibration frequencies of the ball bearing considering not only the centrifugal force and gyroscopic moment of ball but also the waviness of the rolling elements.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.439-448
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• 2012

This paper investigates the load sharing of double circular arc helical gears considering the influence of assembly errors. Based on a load sharing formulae, a three-dimensional finite element tooth contact analysis (TCA) is implemented with commercial software package ANSYS. The finite element grid for the double circular arc gear contact model is automatically generated by using the APDL (ANSYS Parameter Design Language) embedded in ANSYS. The realistic rotation of gears is achieved by using a coupling degree-of-freedom method. Numerical simulations are carried out to exemplify the proposed approach. The distribution of contact stress and bending stress under specific loading conditions are computed and compared with those obtained from Hertz contact theory and empirical formulae to demonstrate the efficiency of the proposed load sharing calculation formulae and TCA approach.

• The Journal of the Acoustical Society of Korea
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• v.6 no.3
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• pp.5-16
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• 1987

In this paper, the sound radiation from a clamped circular plate with a viscoelastic layer excited by impact force is studied both analytically and experimentally. The composite plate vibrations are obtained by using the normal mode analysis and the eigenvalues are obtained by a Mindlin plate theory including the rotary inertia and shear deformation, The contact force developed between the ball and the plate with attached layers is obtained by Hertz contact theory. The radiated sound pressure is calculated by the Rayleigh integral. Prediction of the waveforms of sound radiating from the plate with attached layers and a method for reducing noise generation from the plate by impact force are also shown in this paper.

• Tribology and Lubricants
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• v.31 no.5
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• pp.189-194
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• 2015

This paper focuses on the conformal contact problem. A typical example of conformal contact is the contact between a pin and hole. In particular, this paper focuses on the condition for assuming a contact stress field to be a Hertzian pressure profile by using well-known classical solutions associated with Hertzian contact. Persson first developed the conformal contact analysis method around half a century ago, but there have been no significant improvements since then. The present research also adopted this method, but developed new solutions from the viewpoint of application to structural design. The analysis began with a comparison between Persson°Øs conformal contact stress and the Hertzian stress fields. The next step was to check the differences in the normalized stress values of both. This study used the tolerance for the difference in the peak stresses of Persson°Øs solution and the Hertz solution to validate the Hertzian assumption. This gave the range for the difference in radii of the pin and hole when the contact force and mechanical properties of the material are specified. The results showed that, at a tolerance of 5%, the Hertzian assumption is valid if half of the contact angle is less than 35°ý. In addition, the Hertzian assumption holds even for a relatively long contact length, in contrast to the general incomplete contact problem. This paper discusses these results along with other aspects of the application to the design.