The Rheology of Lubricants at High Shear Rates

1993 ◽  
Vol 115 (4) ◽  
pp. 640-647 ◽  
Author(s):  
R. Feng ◽  
K. T. Ramesh
Keyword(s):  
Kolsky Bar ◽  
Shear Stresses ◽  
Test Duration ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Concentric Cylinders ◽  
Annular Layer ◽  
Short Test ◽  
Torsional Kolsky Bar

A modified torsional Kolsky bar is used to shear a thin annular layer of lubricant held between concentric cylinders. The shear rates obtained range from 4 × 103 to 4 × 104 s−1; the duration of the shear pulse is about 400 microseconds. The shear stress history and the corresponding shear-rate history are deduced using standard torsional Kolsky bar techniques. This experimental technique provides the capability of measuring the shear stresses sustained by fluids at very high shear rates, while the short test duration ensures a minimal rise in temperature due to the associated shear heating. Results are presented for a synthetic lubricant (5P4E) and a mineral oil (HVI650). The lubricants are both observed to be rate-sensitive over the entire range of shear rates examined; the rate-dependence of the shear response is strongly non-Newtonian at high shear rates. Softening during the test is observed for both materials; this softening appears to be largely driven by a thermal mechanism.

The Viscous Behavior of Polymer Modified Lubricating Oils Over a Broad Range of Temperature and Shear Rate

1990 ◽  
Vol 112 (3) ◽  
pp. 417-425 ◽  
Author(s):  
C. S. Peter Wu ◽  
T. Melodick ◽  
S. C. Lin ◽  
J. L. Duda ◽  
E. E. Klaus
Keyword(s):  
Shear Rate ◽  
Polymer Concentration ◽  
Mineral Oil ◽  
Capillary Viscometer ◽  
Viscous Heating ◽  
Shear Stresses ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Newtonian Behavior

A high-shear capillary viscometer was used to determine the viscosity of mineral oil lubricants containing an olefin copolymer up to shear rates of a million reciprocal seconds. Comprehensive measurements were conducted for a range of polymer concentrations from 1–3 wt percent polymer and a temperature range of 38–120° C. The experimental technique utilizes a theoretical analysis procedure to handle the complications associated with viscous heating, the influence of pressure on the viscosity, and the excess pressure drop which occur at the entrance and exit of the capillary. The viscosity of the polymer solutions is determined over the complete range of shear rate starting from the lower Newtonian limit, through the shear-thinning region, and finally, the Newtonian behavior at high shear rates. It is shown that the standard ASTM plot for viscosity-temperature behavior can be used to correlate the viscous behavior for a given polymer concentration over this broad range of shear rates and shear stresses.

Relative Involvement of GPIb/IX-vWF Axis and GPIIb/IIIa in Thrombus Growth at High Shear Rates in the Guinea Pig

1997 ◽  
Vol 17 (5) ◽  
pp. 919-924 ◽  
Author(s):  
Patrick André ◽  
Patricia Hainaud ◽  
Claire Bal dit Sollier ◽  
Leonard I. Garfinkel ◽  
Jacques P. Caen ◽  
...  
Keyword(s):  
Guinea Pig ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates

scholarly journals Microfluidic rheology: A new approach to measure viscosity of ceramic suspensions at extremely high shear rates

Open Ceramics ◽  
2021 ◽  
Vol 5 ◽  
pp. 100052
Author(s):  
V. Carnicer ◽  
C. Alcázar ◽  
M.J. Orts ◽  
E. Sánchez ◽  
R. Moreno
Keyword(s):  
High Shear ◽  
New Approach ◽  
Shear Rates ◽  
High Shear Rates ◽  
Ceramic Suspensions

Flow curves of mixtures of acrylonitrile–styrene copolymers with different molecular weights at extremely high shear rates (abstract)

1991 ◽  
Vol 35 (4) ◽  
pp. 706-706
Author(s):  
Hideroh Takahashi ◽  
Yoshinori Inoue ◽  
Satoru Yamamoto ◽  
Osami Kamigaito
Keyword(s):  
High Shear ◽  
Flow Curves ◽  
Shear Rates ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
High Shear Rates

Comparison of antithrombotic efficacy between edoxaban, a direct factor Xa inhibitor, and fondaparinux, an indirect factor Xa inhibitor under low and high shear rates

2011 ◽  
Vol 106 (12) ◽  
pp. 1062-1068 ◽  
Author(s):  
Naoki Tsuji ◽  
Yuko Honda ◽  
Chikako Kamisato ◽  
Yoshiyuki Morishima ◽  
Toshiro Shibano ◽  
...  
Keyword(s):  
Shear Rate ◽  
Arterial Thrombosis ◽  
Factor Xa ◽  
High Shear ◽  
Shear Rates ◽  
Thrombosis Model ◽  
Perfusion Chamber ◽  
High Shear Rates ◽  
Antithrombotic Effects ◽  
Antithrombotic Efficacy

SummaryEdoxaban is an oral, direct factor Xa (FXa) inhibitor under late-phase clinical development. This study compared the antithrombotic efficacy of edoxaban with that of an indirect FXa inhibitor, fondaparinux, in in vivo venous and arterial thrombosis models and in ex vivo perfusion chamber thrombosis model under low and high shear rates in rats. Venous and arterial thrombi were induced by platinum wire insertion into the inferior vena cava and by application of FeCl3 to the carotid artery, respectively. The perfusion chamber thrombus was formed by blood perfusion into a collagen-coated capillary at 150 s-1 (low shear rate) and 1,600 s-1 (high shear rate). Effective doses of edoxaban that reduced thrombus formation by 50% (ED50) in venous and arterial thrombosis models were 0.076 and 0.093 mg/kg/h, respectively. In contrast, ED50 of fondaparinux in the arterial thrombosis model (>10 mg/kg/h) was markedly higher compared to ED50 in the venous thrombosis model (0.021 mg/kg/h). In the perfusion chamber thrombosis model, the ratio of ED50 under high shear rate (1.13 mg/kg/h) to that under low shear rate (0.63 mg/kg/h) for edoxaban was 1.9, whereas that for fondaparinux was more than 66. While the efficacy of fondaparinux markedly decreased in arterial thrombosis and in a high-shear state, edoxaban exerted consistent antithrombotic effects regardless of flow conditions. These results suggest that shear rate is a key factor in different antithrombotic effects between edoxaban and fondaparinux.

“Viscosity-plus” Effect in Whole Blood at High Shear Rates

Nature ◽  
1969 ◽  
Vol 221 (5178) ◽  
pp. 365-366 ◽  
Author(s):  
WILLIAM I. ROSENBLUM
Keyword(s):  
Whole Blood ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates

The Place of Dielectric Spectroscopy in Probing Electrorheology

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1829-1836 ◽  
Author(s):  
S. Kyvelidis ◽  
G. M. Maistros ◽  
P. Rattray ◽  
H. Block ◽  
J. Akhavan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Working Conditions ◽  
High Shear ◽  
Empirical Correlations ◽  
Electrical Parameters ◽  
Shear Rates ◽  
Uniform Shear ◽  
High Shear Rates ◽  
Er Fluids ◽  
Er Fluid

The measurement of the dielectric spectra of PAnQR based ER fluids under shear and electric fields is discussed and results presented. Data in which either but not both shear or electric fields are present are submitted to analysis in terms of known theories. For flow alone, that analysis provides information on the attenuation of polarization by the uniform shear fields whilst the polarization of quiescent fluids by electric fields may lead to estimates of particles packing within the columns. Permittivity data when both fields are acting is presented, but in the absence of suitable theory, not modelled quantitatively. Empirical correlations are discussed and the conclusion drawn that fibrillation is readily suppressed by even moderate shear rates, although long range dipolar forces still persist to high shear rates. The dc conductance of these fluids have also been measured. This together with permittivity data under ER fluid working conditions has importance in establishing the electrical parameters for any ER fluid.

Sign in / Sign up

Export Citation Format

Share Document