A. A. Abdel Ghany

Bio: A. A. Abdel Ghany is an academic researcher from Cairo University. The author has contributed to research in topics: Lubrication & Manganin. The author has an hindex of 2, co-authored 2 publications receiving 7 citations.

Elastohydrodynamic Behavior of Rolling Elliptical Contacts: Part I: Pressure and Temperature Distributions

Abstract: A two disk machine with a spherical disk mating a plain cylindrical one has been constructed to operate at different elliptical contact situations under various loads and rolling to sliding speeds. The disks axes can skew relative to each other so that various elliptical contacts could be tested. By the aid of specially modified evaporated transducers (Manganin band for pressure measurements and platinum band for temperature measurements), the elastohydrodynamic (EHD) pressure and temperature distributions could be accurately traced. Results, herein presented, confirmed that within the contact zone, the pressure distribution exhibits an almost Hertzian shape but with a second pressure peak (spike) near the trailing (exit) end of the oil film. The temperature has proven to display a distribution analogous to that described by the generated EHD pressure.

Sixty years of EHL

Abstract: It is now 60 years since Ertel produced the first solution to the elastohydrodynamic lubrication (EHL) problem. There has been enormous progress since then, both in numerical modelling and in experimental research on EHL. The moving, rough surface EHL problem can now be solved on laptop-level computers, while maps of film thickness, pressure and temperature can be obtained experimentally from within rolling/sliding contacts. However, there remain some important questions that have not been fully resolved. One of the most contentious is how to describe the rheological properties of lubricants under the very severe conditions present in thin film EHL contacts. A second is how to model mixed lubricated contact, where the fluid film can break down at asperity conjunctions. But perhaps the greatest challenge to researchers in EHL is to produce useful design equations for predicting the performance of machine components operating in EHL and thereby ensure that EHL theory becomes an integral part of the design process. Copyright © 2006 John Wiley & Sons, Ltd.

Thin films in elastohydrodynamic lubrication: The contribution of experiment:

Abstract: This paper reviews the various experimental techniques that have contributed to an understanding of elastohydrodynamic (EHD) lubrication. After a brief historical overview, attention focuses on the main methods for studying the behaviour of lubricant films in lubro, within EHD contacts, in particular ultra thin film interferometry, film thickness mapping, in-contact infrared and Raman spectroscopy, fluorescence and temperature/shear stress mapping. From this review, the important role of the experimentalist in the study of EHD lubrication is identified and appreciated.

Measuring contact pressure distributions under elastohydrodynamic point contacts

Abstract: Circular point contact EHD pressure distributions were investigated under various operating conditions using a thin film piezo-resistive pressure transducer. A series of controlled experiments, in which the active element of the transducer is positioned at various contact cross-sections, was carried out. The results are analysed and presented in the form of isobars. The pressure distribution closely describes the Hertzian pressure profile with a secondary pressure peak appearing prior to and near the exit constriction.

Measuring Surface Temperatures between Rolling Steel Cylinders Using Double-Layer Transducers:

Abstract: The signals of the thin-film transducers previously used for the measurement of temperature distributions in elastohydrodynamic contacts have been influenced by the high pressures occurring At pure rolling conditions when the temperature increase is small, the error caused by pressure reaches nearly the order of magnitude of the temperature signal to be recorded Using double-layer transducers of a novel type, a reduction of this error of over 90 per cent can be achieved In this paper temperature measurements at pure rolling conditions are described It has been shown that a distinct temperature spike occurs at the constriction at the trailing edge of the elastohydrodynamic contact