Flow behavior of soda-lime glass at high pressures and high shear rates

1998 ◽  
Author(s):  
S. Sundaram ◽  
R. J. Clifton

The Eyring theory of viscous flow suggests that lubricating oils should exhibit shear thinning when the shear stress exceeds about 5 MPa. The results of friction experiments in rolling-contact disc machines where very high pressures are generated in the lubricant film support this prediction, but are open to the criticism that the fluid is subjected to a high pressure for such a short time ( ca . 10 -4 s) that an equilibrium state may not be reached. In the present investigation the appropriate condition of the lubricant is achieved, not by subjecting it to very high pressures but by maintaining it in the supercooled state. The lubricant is thus in a condition of equili­brium and the shear experiments are carried out at atmospheric pressure. The lubricant specimen is retained in a suitably adapted split Hopkinson torsion bar, and at the high rates of shear applied ( ca . 10 4 s -1 ) the shear stress at sufficiently low temperatures can exceed 5 MPa. By this tech­nique the shear pulse is applied for a sufficiently short time ( ca . 10 -3 s) to avoid viscous heating of the sample, which bedevils normal viscometry at high shear rates. Two fluids were tested: polyphenyl ether 5P4E and a mineral oil Shell HVI 650. Nonlinearity in the shear-stress-shear-strain-rate relation was found when the stress exceeded about 3 MPa. The elastic shear modulus G ∞ was also measured, yielding ca . 500 MPa for 5P4E and ca . 50 MPa for HVI 650.These values compare with ca . 1100 MPa and 300 MPa as found by the high-frequency oscillating shear technique at small strains.


1990 ◽  
Vol 47 (7) ◽  
pp. 611-617 ◽  
Author(s):  
Hideroh TAKAHASHI ◽  
Yoshinori INOUE ◽  
Osami KAMIGAITO ◽  
Kunihiro OSAKI

1996 ◽  
Vol 118 (1) ◽  
pp. 162-168 ◽  
Author(s):  
Y. Zhang ◽  
K. T. Ramesh

Knowledge of the behavior of lubricants over a wide range of pressures and shear rates is fundamental to an understanding of elastohydrodynamic (EHD) lubrication. The mechanical properties of elastohydrodynamic lubricants have been measured by a number of researchers under the conditions of low pressures and low shear rates, as well as under high pressures and high shear rates. This paper presents experimental results for the synthetic lubricant 5P4E subjected to moderate pressures (60 MPa to 700 MPa) and high shear rates (105 s−1) using the technique of pressure-shear plate impact. Thin layers (25 μm thick) of the lubricant are confined between two hard elastic plates; the assembly is subjected to impact by a parallel plate in a manner designed to induce both compression and shear loading. For approximately 1 μs the compressed lubricant is subjected to a simple shearing motion; during that time, continuous records of the shear stress and shear rate are obtained using laser interferometry. Three test configurations were used in order to cover the pressure range, and special techniques were developed for preparing the specimen sandwich. The pressure range covered includes both the liquid and glassy states of the lubricant. The results show that a limiting shear stress model is an appropriate model for lubricant behavior under these conditions. The experimental results also show little change in the lubricant shearing behavior across the glass transition.


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

Open Ceramics ◽  
2021 ◽  
Vol 5 ◽  
pp. 100052
Author(s):  
V. Carnicer ◽  
C. Alcázar ◽  
M.J. Orts ◽  
E. Sánchez ◽  
R. Moreno

1991 ◽  
Vol 35 (4) ◽  
pp. 706-706
Author(s):  
Hideroh Takahashi ◽  
Yoshinori Inoue ◽  
Satoru Yamamoto ◽  
Osami Kamigaito

2011 ◽  
Vol 106 (12) ◽  
pp. 1062-1068 ◽  
Author(s):  
Naoki Tsuji ◽  
Yuko Honda ◽  
Chikako Kamisato ◽  
Yoshiyuki Morishima ◽  
Toshiro Shibano ◽  
...  

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.


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