The High Shear Stress Rheology of Liquid Lubricants at Pressures of 2 to 200 MPa

1990 ◽  
Vol 112 (2) ◽  
pp. 246-252 ◽  
Author(s):  
S. Bair ◽  
W. O. Winer
Keyword(s):  
Shear Stress ◽  
Glass Transition ◽  
Shear Flow ◽  
Flow Characteristics ◽  
Steady Shear ◽  
Shear Stresses ◽  
High Shear ◽  
High Shear Stress ◽  
Limiting Shear Stress ◽  
Steady Shear Flow

The steady shear flow characteristics of two liquid lubricants were measured in a new rheometer at shear stresses to 10 MPa. All measurements were performed well below the glass transition pressure. Both Newtonian and rate-independent (limiting shear stress) behaivor was observed.

scholarly journals Response of shear stress to ac electric fields under steady shear flow in a droplet-dispersed phase

2009 ◽  
Vol 80 (6) ◽  
Author(s):  
Yang Ho Na ◽  
Kohei Aida ◽  
Ryosuke Sakai ◽  
Toyoji Kakuchi ◽  
Hiroshi Orihara
Keyword(s):  
Shear Stress ◽  
Shear Flow ◽  
Electric Fields ◽  
Steady Shear ◽  
Dispersed Phase ◽  
Ac Electric Fields ◽  
Steady Shear Flow

Strain distribution over plaques in human coronary arteries relates to shear stress

2008 ◽  
Vol 295 (4) ◽  
pp. H1608-H1614 ◽  
Author(s):  
Frank J. H. Gijsen ◽  
Jolanda J. Wentzel ◽  
Attila Thury ◽  
Frits Mastik ◽  
Johannes A. Schaar ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Arteries ◽  
Plaque Rupture ◽  
Stress And Strain ◽  
Shear Stresses ◽  
High Shear ◽  
High Shear Stress ◽  
Plaque Composition ◽  
Downstream Region ◽  
Shear Stress And Strain

Once plaques intrude into the lumen, the shear stress they are exposed to alters with hitherto unknown consequences for plaque composition. We investigated the relationship between shear stress and strain, a marker for plaque composition, in human coronary arteries. We imaged 31 plaques in coronary arteries with angiography and intravascular ultrasound. Computational fluid dynamics was used to obtain shear stress. Palpography was applied to measure strain. Each plaque was divided into four regions: upstream, throat, shoulder, and downstream. Average shear stress and strain were determined in each region. Shear stress in the upstream, shoulder, throat, and downstream region was 2.55 ± 0.89, 2.07 ± 0.98, 2.32 ± 1.11, and 0.67 ± 0.35 Pa, respectively. Shear stress in the downstream region was significantly lower. Strain in the downstream region was also significantly lower than the values in the other regions (0.23 ± 0.08% vs. 0.48 ± 0.15%, 0.43 ± 0.17%, and 0.47 ± 0.12%, for the upstream, shoulder, and throat regions, respectively). Pooling all regions, dividing shear stress per plaque into tertiles, and computing average strain showed a positive correlation; for low, medium, and high shear stress, strain was 0.23 ± 0.10%, 0.40 ± 0.15%, and 0.60 ± 0.18%, respectively. Low strain colocalizes with low shear stress downstream of plaques. Higher strain can be found in all other plaque regions, with the highest strain found in regions exposed to the highest shear stresses. This indicates that high shear stress might destabilize plaques, which could lead to plaque rupture.

Shear stress experienced by echinoderm eggs in the oviduct during spawning: potential role in the evolution of egg properties

1999 ◽  
Vol 202 (22) ◽  
pp. 3111-3119 ◽  
Author(s):  
F.I. Thomas ◽  
T.F. Bolton
Keyword(s):  
Shear Stress ◽  
Laminar Flow ◽  
Potential Role ◽  
Shear Stresses ◽  
High Shear ◽  
High Shear Stress ◽  
Arbacia Punctulata ◽  
Shear Rates ◽  
Flow Through

Shear stresses experienced by eggs in the oviduct of the echinoid Arbacia punctulata during spawning were calculated using engineering equations that describe laminar flow through pipes. Shear stresses in the oviduct ranged from 0 to 58.7 Pa. Two properties of eggs were identified that have the potential either to minimize the shear stress in the oviduct or to reduce the damage experienced by eggs exposed to high shear stress. These properties are the viscosity of the eggs and the presence of extracellular layers on eggs of A. punctulata. The viscosity of eggs decreases with increasing shear rates, which reduces the magnitude of shear stress experienced in the oviduct, while the extracellular layers mitigate the effect of shear stress on the eggs. Eggs with intact extracellular layers were damaged less frequently than were those with the extracellular layers removed. The results of this research indicate that physical stresses may be important selective factors in the evolution of gamete properties.

The Initiation and Propagation of Fatigue Cracks in Mild Steel Pieces of Square Section

1954 ◽  
Vol 4 (1) ◽  
pp. 1-18 ◽  
Author(s):  
H. L. Cox ◽  
J. E. Field
Keyword(s):  
Shear Stress ◽  
Tensile Stress ◽  
Mild Steel ◽  
Fatigue Cracks ◽  
Maximum Shear Stress ◽  
Shear Stresses ◽  
High Shear ◽  
Stress Range ◽  
High Shear Stress ◽  
General Direction

SummaryAn investigation has been made to determine the positions and directions of initiation and the directions of propagation of fatigue cracks and to examine the correlation between these positions and directions and the planes on which maximum tensile and maximum shear stresses are generated.To afford as wide a range as possible of the ratio of maximum shear stress to maximum tensile stress, tests have been made under combinations of alternating bending and torsion; and in order to separate partially the regions of high shear stress from those of high direct stress, the tests have been made on pieces of square section with the plane of bending parallel to one diagonal of the section. Two series of tests have been made; one a preliminary series on pieces having no parallel portion and the other on pieces having a parallel portion about three times the length of the side of the square section. The positions and directions of initiation and the directions of propagation of fatigue cracks have been observed and compared with the positions and directions of the maximum tensile and shear stresses.Fatigue cracks may be initiated as a result of either high shear stress or high tensile stress and in the present series of tests on mild steel, cracking in tension has occurred in preference to cracking in shear when the ratio of the tensile stress range to the shear stress range has exceeded about 1.6; for values of this ratio less than 1.6, the cracks started in shear (and vice versa); propagation along the plane of maximum shear appears to be preferred up to a slightly greater value of the tensile/shear ratio (about 1.7 possibly). The general direction of a crack formed as a result of high tension usually follows the plane of maximum tension and that of a crack formed as a result of shear usually follows the plane of maximum shear. In detail both types of crack—in this mild steel—deviate quite widely from their general directions but this deviation bears no obvious relation to the microstructure of the material. Cracks propagating along one plane of maximum shear occasionally show a marked tendency to branch along the associated plane of maximum shear; but this tendency is not always observed and in other cases no tendency to branch has been noted.

The ultimate shear stress of fluids at high pressures measured by a modified impact microviscometer

1979 ◽  
Vol 365 (1720) ◽  
pp. 31-41 ◽  
Keyword(s):  
Shear Stress ◽  
Radial Stress ◽  
High Pressures ◽  
Shear Stresses ◽  
High Shear ◽  
Polyphenyl Ether ◽  
Ultimate Shear Stress ◽  
Limiting Shear Stress ◽  
Traction Test ◽  
The Impact

The impact microviscometer has been modified so that the ball can be rotated after an entrapment is formed. This rotation produces an extra circumferential shear stress which is much larger than the radial stress caused by the outward flow. Three fluids were studied by using this device. All displayed non-Newtonian behaviour at high shear stresses and appeared to be tending towards a limiting shear stress with increasing shear rate at pressures from 0.3 to 2 GPa. Data from one of the fluids (polyphenyl ether) were compared with results from a ball on plate traction test and a remarkable correlation was found. It seems reasonable to attribute the peak in the traction-slip curve to the ultimate shear stress that the lubricant can support.

Non-Newtonian steady shear flow characteristics of waxy crude oil

2008 ◽  
Vol 15 (S1) ◽  
pp. 326-328 ◽  
Author(s):  
Shu-xin Huang ◽  
Xin Chen ◽  
Chuan-jing Lu ◽  
Lei Hou ◽  
Yu-run Fan
Keyword(s):  
Shear Flow ◽  
Crude Oil ◽  
Flow Characteristics ◽  
Steady Shear ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Steady Shear Flow

scholarly journals Linear Viscoelastic Relation Concerning Shear Stresses at the Start and Cessation of Steady Shear Flow

1976 ◽  
Vol 4 (4) ◽  
pp. 166-169 ◽  
Author(s):  
Kunihiro OSAKI ◽  
Ashita MURAI ◽  
Nobuo BESSHO ◽  
Bong Shik KIM
Keyword(s):  
Shear Flow ◽  
Steady Shear ◽  
Shear Stresses ◽  
Steady Shear Flow ◽  
Linear Viscoelastic

Relaxation dynamics of entangled polymer liquids in steady shear flow

2003 ◽  
Vol 47 (2) ◽  
pp. 469-482 ◽  
Author(s):  
Javier Sanchez-Reyes ◽  
Lynden A. Archer
Keyword(s):  
Shear Flow ◽  
Steady Shear ◽  
Relaxation Dynamics ◽  
Steady Shear Flow ◽  
Polymer Liquids ◽  
Entangled Polymer
Sign in / Sign up

Export Citation Format

Share Document