Boundary Conditions for Elastohydrodynamics of Circular Point Contacts

Hydrodynamic friction in undistorted, concentrated point contacts is studied. Experimental measurements are obtained using a ball-and-plate machine, the plate being either flat, or with a circular groove. In the latter case, the ball drive-shaft is angled to vary the asymmetry of the contact. Reasonable correlation with experiment is obtained using a hydrodynamic theory which embraces the rolling, sliding and cavitation components of the total friction.

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Transient analysis of isothermal elastohydrodynamic circular point contacts

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/095440620121500103 ◽

2001 ◽

Vol 215 (10) ◽

pp. 1159-1172 ◽

Cited By ~ 7

Author(s):

D Jalali Vahid ◽

H Rahnejat ◽

Z M Jin ◽

D Downson

Keyword(s):

Transient Analysis ◽

Solution Method ◽

Numerical Solutions ◽

Flat Glass ◽

Point Contact ◽

Elastohydrodynamic Lubrication ◽

Point Contacts ◽

Good Qualitative Agreement ◽

Circular Point ◽

Good Agreement

In this paper a solution method is presented for the transient isothermal elastohydrodynamic lubrication of point contact conjunctions, based upon the Newton-Raphson scheme and low iteration relaxation. The numerical results are compared with the numerical and experimental observations of others for the circular point contact of a ball against a flat glass disc under oscillating conditions. Good agreement has been found with other numerical solutions. The comparison with the experimental results shows good qualitative agreement.

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Isoviscous elastohydrodynamic lubrication of circular point contacts with particular reference to metal-on-metal hip implants

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1243/135065003322445313 ◽

2003 ◽

Vol 217 (5) ◽

pp. 397-402 ◽

Cited By ~ 6

Author(s):

D Jalali- Vahid ◽

Z. M. Jin ◽

D Dowson

Keyword(s):

Numerical Solutions ◽

Elastohydrodynamic Lubrication ◽

Hip Implants ◽

Point Contacts ◽

Hip Joints ◽

Circular Point ◽

Metal On Metal ◽

Artificial Hip Joints

A full numerical analysis of elastohydrodynamic lubrication (EHL) of circular point contacts was carried out in the present study under isoviscous conditions with particular reference to metal-on-metal artificial hip joints, using a modified Newton-Raphson method. It was found to be possible to incorporate directly the physiological conditions, representative of typical metal-on-metal hip implants under in-vivo walking or in-vitro simulator testing, in the present numerical solutions. The predicted minimum and central film thicknesses were compared favourably with those estimated from various formulae available in the literature. In particular, it was shown that both the minimum and the central film thickness expressions derived by Hamrock and Dowson were reasonably accurate for all the conditions considered in the present study.

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Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068795 ◽

1970 ◽

Vol 28 ◽

pp. 360-361

Author(s):

John W. Coleman

Keyword(s):

Boundary Conditions ◽

High Performance ◽

Force Fields ◽

Optical Design ◽

Direct Conversion ◽

Design Engineering ◽

Design Data ◽

Scalar Potentials ◽

Geometric Elements ◽

At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

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