[article] 
inTransactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 8 p.

Titre :	Scale effects in generalized Newtonian elastohydrodynamic films
Type de document :	texte imprimé
Auteurs :	Ilya I. Kudish, Auteur ; P. Kumar, Auteur ; M. M. Khonsari, Auteur
Année de publication :	2015
Article en page(s) :	8 p.
Note générale :	Tribologgy
Langues :	Anglais (eng)
Mots-clés :	Pressure Viscosity Lubricants Shear (Mechanics) Film thickness Rheology Fluids
Résumé :	The estimation or prediction of elastohydrodynamic lubrication (EHL) film thickness requires knowledge of the lubricant properties. Today, in many instances, the lubricant properties have been obtained from a measurement of the central film thickness and the assumption of a classical Newtonian film-thickness formula. This technique has the practical advantage of using an effective pressure-viscosity coefficient, which compensates for shear-thinning. We have shown by a perturbation analysis of limiting cases for fluid with Carreau rheology (represented by Newtonian and power fluid) and by a full EHL numerical solution for Carreau fluid that the practice of extrapolating from a laboratory scale measurement of film thickness to the film thickness of an operating contact may substantially overestimate the film thickness in the real machine if the machine scale is smaller and the lubricant is shear-thinning within the inlet zone. The intention here is to show that errors result from extrapolation of Newtonian formulas to different scale and not to provide advice regarding quantitative engineering calculations.
En ligne :	http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468110

[article] Scale effects in generalized Newtonian elastohydrodynamic films [texte imprimé] / Ilya I. Kudish, Auteur ; P. Kumar, Auteur ; M. M. Khonsari, Auteur . - 2015 . - 8 p.
Tribologgy
Langues : Anglais (eng)
in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 8 p.

Mots-clés :	Pressure Viscosity Lubricants Shear (Mechanics) Film thickness Rheology Fluids
Résumé :	The estimation or prediction of elastohydrodynamic lubrication (EHL) film thickness requires knowledge of the lubricant properties. Today, in many instances, the lubricant properties have been obtained from a measurement of the central film thickness and the assumption of a classical Newtonian film-thickness formula. This technique has the practical advantage of using an effective pressure-viscosity coefficient, which compensates for shear-thinning. We have shown by a perturbation analysis of limiting cases for fluid with Carreau rheology (represented by Newtonian and power fluid) and by a full EHL numerical solution for Carreau fluid that the practice of extrapolating from a laboratory scale measurement of film thickness to the film thickness of an operating contact may substantially overestimate the film thickness in the real machine if the machine scale is smaller and the lubricant is shear-thinning within the inlet zone. The intention here is to show that errors result from extrapolation of Newtonian formulas to different scale and not to provide advice regarding quantitative engineering calculations.
En ligne :	http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468110