Publication detail
An Experimental Validation of the Recently Discovered Scale Effect in Generalized Newtonian EHL
KŘUPKA, I. HARTL, M. BAIR, S. KUMAR, P. KHONSARI, M.M.
Czech title
Experimentální ověření vlivu velikosti třecích těles v obecném Newtonovském EHD modelu
English title
An Experimental Validation of the Recently Discovered Scale Effect in Generalized Newtonian EHL
Type
journal article - other
Language
en
Original abstract
New quantitative numerical simulations of the elastohydrodynamic lubrication (EHL) film forming ability of generalized Newtonian liquids have elucidated a previously unrecognized property of EHL films. The dependency of the film thickness on the scale of the contact is greater when the viscosity is shear dependent within the inlet. Measurements of film thickness were performed in a ball on disc experiment using balls ranging from 5.5 to 35 mm in diameter. Three liquids were investigated with varying shear dependence in the range of stress important to film forming. The experimental results confirm the previous analytical findings. Numerical simulations using the measured viscosities show that the increased scale sensitivity is substantially the result of shear-thinning. However, the smallest scales produced films thinner than even the shear-dependent prediction, possibly indicating molecular degradation. It is quite likely that some machine components, which were designed using the effective viscous properties derived from a larger scale film thickness measurement, are operating with substantially lower film thickness than the designer had intended.
Czech abstract
Článek shrnuje výsledky experimentálního ověření vlivu rozměrů třecích těles modelového kontaktu na přenositelnost získaných údajů na reálný mazaný kontakt.
English abstract
New quantitative numerical simulations of the elastohydrodynamic lubrication (EHL) film forming ability of generalized Newtonian liquids have elucidated a previously unrecognized property of EHL films. The dependency of the film thickness on the scale of the contact is greater when the viscosity is shear dependent within the inlet. Measurements of film thickness were performed in a ball on disc experiment using balls ranging from 5.5 to 35 mm in diameter. Three liquids were investigated with varying shear dependence in the range of stress important to film forming. The experimental results confirm the previous analytical findings. Numerical simulations using the measured viscosities show that the increased scale sensitivity is substantially the result of shear-thinning. However, the smallest scales produced films thinner than even the shear-dependent prediction, possibly indicating molecular degradation. It is quite likely that some machine components, which were designed using the effective viscous properties derived from a larger scale film thickness measurement, are operating with substantially lower film thickness than the designer had intended.
Keywords in Czech
Elastohydrodynamické mazání; Tloušťka filmu; Reologie
Keywords in English
Elastohydrodynamic; Film thickness; EHL; Rheology
RIV year
2008
Released
03.12.2008
Publisher
Springer
ISSN
1023-8883
Journal
Tribology Letters
Volume
33
Number
X
Pages from–to
1–9
Pages count
9
BIBTEX
@article{BUT48047,
author="Ivan {Křupka} and Martin {Hartl},
title="An Experimental Validation of the Recently Discovered Scale Effect in Generalized Newtonian EHL",
journal="Tribology Letters",
year="2008",
volume="33",
number="X",
month="December",
pages="1--9",
publisher="Springer",
issn="1023-8883"
}