Details
| Original language | English |
|---|---|
| Pages (from-to) | 126-131 |
| Number of pages | 6 |
| Journal | Tribology international |
| Volume | 79 |
| Early online date | 16 Jun 2014 |
| Publication status | Published - Nov 2014 |
Abstract
The new quantitative approach to elastohydrodynamic lubrication requires a description of the steady shear dependent viscosity for calculations of film thickness and friction. This property can be obtained from measurements in pressurized thin-film Couette viscometers. However, frequency dependent viscosity can be obtained from a torsionally vibrating quartz crystal viscometer at high pressure or a relatively simple ambient pressure measurement with a shear impedance spectrometer. Here it is shown for squalane and for a cyclic hydrocarbon and for a diester that both the steady shear dependent viscosity and the frequency dependent viscosity obey time-temperature-pressure superposition with the simplest shifting rule over the range of conditions investigated. Flow curves shift along a constant steady stress path or a constant complex modulus path. The Cox-Merz rule has been confirmed only for squalane and then only near the transition. The EHL friction for squalane at low pressure may be predicted with fair accuracy from the frequency dependent viscosity measured at ambient pressure. It appears that the Cox-Merz rule only applies to low-molecular-weight liquids when the molecule is composed of a long chain.
Keywords
- Cox-Merz rule, Elastohydrodynamic lubrication, Shear thinning, Time-temperature-pressure superposition
ASJC Scopus subject areas
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Materials Science(all)
- Surfaces, Coatings and Films
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In: Tribology international, Vol. 79, 11.2014, p. 126-131.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Oscillatory and steady shear viscosity
T2 - The Cox-Merz rule, superposition, and application to EHL friction
AU - Bair, Scott
AU - Yamaguchi, Tsuyoshi
AU - Brouwer, Ludwig
AU - Schwarze, Hubert
AU - Vergne, Philippe
AU - Poll, Gerhard
N1 - Funding Information: Bair was supported by the Center for Compact and Efficient Fluid Power, a National Science Foundation Engineering Research Center funded under cooperative agreement number EEC-0540834 . Yamaguchi is grateful to Professor Tatsuro Matsuoka (Nagoya University) for discussion.
PY - 2014/11
Y1 - 2014/11
N2 - The new quantitative approach to elastohydrodynamic lubrication requires a description of the steady shear dependent viscosity for calculations of film thickness and friction. This property can be obtained from measurements in pressurized thin-film Couette viscometers. However, frequency dependent viscosity can be obtained from a torsionally vibrating quartz crystal viscometer at high pressure or a relatively simple ambient pressure measurement with a shear impedance spectrometer. Here it is shown for squalane and for a cyclic hydrocarbon and for a diester that both the steady shear dependent viscosity and the frequency dependent viscosity obey time-temperature-pressure superposition with the simplest shifting rule over the range of conditions investigated. Flow curves shift along a constant steady stress path or a constant complex modulus path. The Cox-Merz rule has been confirmed only for squalane and then only near the transition. The EHL friction for squalane at low pressure may be predicted with fair accuracy from the frequency dependent viscosity measured at ambient pressure. It appears that the Cox-Merz rule only applies to low-molecular-weight liquids when the molecule is composed of a long chain.
AB - The new quantitative approach to elastohydrodynamic lubrication requires a description of the steady shear dependent viscosity for calculations of film thickness and friction. This property can be obtained from measurements in pressurized thin-film Couette viscometers. However, frequency dependent viscosity can be obtained from a torsionally vibrating quartz crystal viscometer at high pressure or a relatively simple ambient pressure measurement with a shear impedance spectrometer. Here it is shown for squalane and for a cyclic hydrocarbon and for a diester that both the steady shear dependent viscosity and the frequency dependent viscosity obey time-temperature-pressure superposition with the simplest shifting rule over the range of conditions investigated. Flow curves shift along a constant steady stress path or a constant complex modulus path. The Cox-Merz rule has been confirmed only for squalane and then only near the transition. The EHL friction for squalane at low pressure may be predicted with fair accuracy from the frequency dependent viscosity measured at ambient pressure. It appears that the Cox-Merz rule only applies to low-molecular-weight liquids when the molecule is composed of a long chain.
KW - Cox-Merz rule
KW - Elastohydrodynamic lubrication
KW - Shear thinning
KW - Time-temperature-pressure superposition
UR - http://www.scopus.com/inward/record.url?scp=84903644007&partnerID=8YFLogxK
U2 - 10.1016/j.triboint.2014.06.001
DO - 10.1016/j.triboint.2014.06.001
M3 - Article
AN - SCOPUS:84903644007
VL - 79
SP - 126
EP - 131
JO - Tribology international
JF - Tribology international
SN - 0301-679X
ER -