Kvantitativní tloušťka elastohydrodynamického mazacího filmu u mechanicky degradovaných olejů

Quantitative elastohydrodynamic film thickness of mechanically degraded oil

journal article - other

en

The low-shear viscosities of new oil and used (degraded) oil were measured to moderately high pressure. Shear-thinning flow curves were generated over a range of shear stress important to EHL film forming. Mechanical shear degradation only affected the viscosity at low shear stress while the viscosity at high stress remained unchanged. A recently published film thickness equation for double-Newtonian shear-thinning, employing the measured rheology, predicts the surprising result that thickness of the EHL film was not changed by the degradation although the low-shear viscosities were reduced substantially. Colorimetric measurements of the film thicknesses validate the predictions. Concern over the permanent loss in viscosity due to degradation may be misplaced when addressing EHL films.

Článek shrnuje srovnání vypočítaných a naměřených hodnot tloušťky mazacího filmu v kontaltu u mechanicky degradovaných olejů. V článku je ukázána možnost dostatečně přesné predikce na základě realistických reologických modelů.

The low-shear viscosities of new oil and used (degraded) oil were measured to moderately high pressure. Shear-thinning flow curves were generated over a range of shear stress important to EHL film forming. Mechanical shear degradation only affected the viscosity at low shear stress while the viscosity at high stress remained unchanged. A recently published film thickness equation for double-Newtonian shear-thinning, employing the measured rheology, predicts the surprising result that thickness of the EHL film was not changed by the degradation although the low-shear viscosities were reduced substantially. Colorimetric measurements of the film thicknesses validate the predictions. Concern over the permanent loss in viscosity due to degradation may be misplaced when addressing EHL films.

zlepšovač viskozity; vysokotlaká reologie; tloušťka EHD filmu; mechanická smyková degradace

Viscosity modifier; High pressure rheology; EHL film thickness; Mechanical shear degradation

2013

19.02.2013

Elsevier

EU

0301-679X

65

8

33–38

6