Viscometric Analysis of Dispersions at Small Shear Stresses

1956 ◽  
Vol 27 (5) ◽  
pp. 468-471 ◽  
Author(s):  
Raymond R. Myers ◽  
John C. Miller ◽  
A. C. Zettlemoyer
Keyword(s):  
Shear Stresses ◽  
Small Shear

Rheological properties of ethylene-propylene copolymers at small shear stresses

1982 ◽  
Vol 24 (6) ◽  
pp. 1488-1494 ◽  
Author(s):  
N.P. Zoteyev ◽  
G.M. Bartenev ◽  
N.V. Yermilova ◽  
O.I. Zoteyeva
Keyword(s):  
Rheological Properties ◽  
Shear Stresses ◽  
Ethylene Propylene ◽  
Small Shear

scholarly journals A dynamical model of a crystal structure. III

1949 ◽  
Vol 196 (1045) ◽  
pp. 182-194 ◽  
Keyword(s):  
Repulsive Interaction ◽  
Shear Stresses ◽  
Displacement Curve ◽  
Plastic Yielding ◽  
Maximum Shear Strain ◽  
Perfect Lattice ◽  
Interaction Terms ◽  
Shear Strains ◽  
Sine Law ◽  
Small Shear

A calculation of the maximum shear strain under which a two-dimensional close-packed lattice is stable has been carried out in terms of the forces between the lattice components. Two types of force were used; those between floating bubbles, which enabled a comparison with experiments on actual rafts of bubbles to be made, and also the forces derived from a potential V = Ae β r 2 , which form has been frequently proposed as an approximation to the repulsive interaction terms between metal ions. The conclusion reached is that this maximum strain may be considerably less than that deduced from a simple sine law approximation to the shear force versus displacement curve. Detailed consideration is given to edge effects in bubble rafts, and reasonable agreement with experimental results obtained. The overall result is that the formation of dislocations and consequent plastic yielding can occur in an initially perfect lattice only at quite large shear strains. The analogy with metals is discussed, and we conclude that the low strengths of metallic single crystals are explicable only on the assumption that they are not perfect and that dislocations already exist in them and move under very small shear stresses.

Influence of gas bubbles on creep of copper under small shear stresses

1986 ◽  
Vol 2 (2) ◽  
pp. 129-132 ◽  
Author(s):  
V.V. Kutumbarao ◽  
G.W. Greenwood
Keyword(s):  
Gas Bubbles ◽  
Shear Stresses ◽  
Small Shear

Direct Strain Oscillation: a new oscillatory method enabling measurements at very small shear stresses and strains

2002 ◽  
Vol 41 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Jörg Läuger ◽  
Klaus Wollny ◽  
Siegfried Huck
Keyword(s):  
Shear Stresses ◽  
Small Shear

scholarly journals Rayleigh–Bénard Instability of an Ellis Fluid Saturating a Porous Medium

2021 ◽  
Author(s):  
Michele Celli ◽  
Antonio Barletta ◽  
Pedro V. Brandão
Keyword(s):  
Porous Medium ◽  
Linear Instability ◽  
Shear Stresses ◽  
Small Temperature ◽  
Ellis Model ◽  
Threshold Conditions ◽  
Horizontal Pressure ◽  
Rayleigh Benard ◽  
Small Shear ◽  
Shear Thinning Fluid

AbstractThe Ellis model describes the apparent viscosity of a shear–thinning fluid with no singularity in the limit of a vanishingly small shear stress. In particular, this model matches the Newtonian behaviour when the shear stresses are very small. The emergence of the Rayleigh–Bénard instability is studied when a horizontal pressure gradient, yielding a basic throughflow, is prescribed in a horizontal porous layer. The threshold conditions for the linear instability of this system are obtained both analytically and numerically. In the case of a negligible flow rate, the onset of the instability occurs for the same parametric conditions reported in the literature for a Newtonian fluid saturating a porous medium. On the other hand, when high flow rates are considered, a negligibly small temperature difference imposed across the horizontal boundaries is sufficient to trigger the convective instability.

scholarly journals Repeated erosion of cohesive sediments with biofilms

2014 ◽  
Vol 39 ◽  
pp. 9-14 ◽  
Author(s):  
K. Valentine ◽  
G. Mariotti ◽  
S. Fagherazzi
Keyword(s):  
Amplitude Modulation ◽  
Extracellular Polymeric Substances ◽  
Sediment Resuspension ◽  
Pulse Amplitude ◽  
Shear Stresses ◽  
Pulse Amplitude Modulation ◽  
Cohesive Sediments ◽  
Physical Processes ◽  
Small Shear ◽  
Low Shear

Abstract. This study aims to explore the interplay between biofilms and erodability of cohesive sediments. Erosion experiments were run in four laboratory annular flumes with natural sediments. After each erosion the sediment was allowed to settle, mimicking intermittent physical processes like tidal currents and waves. The time between consecutive erosion events ranged from 1 to 12 days. Turbidity of the water column caused by sediment resuspension was used to determine the erodability of the sediments with respect to small and moderate shear stresses. Erodability was also compared on the basis of the presence of benthic biofilms, which were quantified using a Pulse-Amplitude Modulation (PAM) Underwater Fluorometer. We found that frequent erosion lead to the establishment of a weak biofilm, which reduced sediment erosion at small shear stresses (around 0.1 Pa). If prolonged periods without erosion were present, the biofilm fully established, resulting in lower erosion at moderate shear stresses (around 0.4 Pa). We conclude that an unstructured extracellular polymeric substances (EPS) matrix always affect sediment erodability at low shear stresses, while only a fully developed biofilm mat can reduce sediment erodability at moderate shear stresses.

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part IV: Laboratory Measurement of Mechanical Properties and Mechanical Actions of Tires Relating to Treadwear

1986 ◽  
Vol 14 (4) ◽  
pp. 264-291
Author(s):  
K. L. Oblizajek ◽  
A. G. Veith
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Contact Zone ◽  
Flexural Rigidity ◽  
Comprehensive Evaluation ◽  
Shear Stiffness ◽  
Shear Stresses ◽  
Lateral Shear ◽  
Band Bending ◽  
Tread Rubber

Abstract Treadwear is explained by specific mechanical properties and actions of tires. Rubber shear stresses in the contact zone between the tire and the road become large at large slip angles. When normal stresses are insufficient to prevent sliding at the rear of the footprint, wear occurs at a rate that depends on test severity. Two experimental approaches are described to relate treadwear to tire characteristics. The first uses transducers imbedded in a simulated road surface to obtain direct measurements of contact stresses on the loaded, freely-rolling, steered tires. The second approach is developed with the aid of a simple carcass, tread-band, tread-rubber tire model. Various tire structural configurations; characterized by carcass spring rate, edgewise flexural band stiffness, and tread rubber shear stiffness; are simulated and lateral shear stress response in the contact zone is determined. Tires featuring high band stiffness and low carcass stiffness generate lower lateral shear stress levels. Furthermore, coupling of tread-rubber stiffness and band flexural rigidity are important in determining level of shear stresses. Laboratory measurements with the described apparatus produced values of tread-band bending and carcass lateral stiffness for several tire constructions. Good correlation is shown between treadwear and a broad range of tire stiffness and test course severities.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

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