Publication result 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.

Original Title

An Experimental Validation of the Recently Discovered Scale Effect in Generalized Newtonian EHL

English Title

An Experimental Validation of the Recently Discovered Scale Effect in Generalized Newtonian EHL

Type

Peer-reviewed article not indexed in WoS or Scopus

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.

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

Elastohydrodynamic; Film thickness; EHL; Rheology

Key words in English

Elastohydrodynamic; Film thickness; EHL; Rheology

Authors

KŘUPKA, I.; HARTL, M.; BAIR, S.; KUMAR, P.; KHONSARI, M.M.

RIV year

2010

Released

03.12.2008

Publisher

Springer

ISBN

1023-8883

Periodical

Tribology letter

Volume

33

Number

X

State

Kingdom of the Netherlands

Pages from

1

Pages to

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 letter",
  year="2008",
  volume="33",
  number="X",
  pages="1--9",
  issn="1023-8883"
}