Effects of variable normal stress on rock friction: Observations and constitutive equations

1992 ◽  
Vol 97 (B4) ◽  
pp. 4923 ◽  
Author(s):  
M. F. Linker ◽  
J. H. Dieterich
Keyword(s):  
Normal Stress ◽  
Constitutive Equations ◽  
Rock Friction

Fundamental Characteristics of Viscoelastic Fluids Simulated by a Bead-Spring-Damper Macro Model With Interaction

2000 ◽  
Author(s):  
Takuji Ishikawa ◽  
Nobuyoshi Kawabata ◽  
Katsushi Fujita ◽  
Yutaka Miyake
Keyword(s):  
Normal Stress ◽  
Constitutive Equations ◽  
Viscoelastic Fluids ◽  
Polymer Chains ◽  
Viscoelastic Flow ◽  
Simple Shear Flow ◽  
Tetrahedral Structure ◽  
Macro Model ◽  
Normal Stress Differences ◽  
Basic Characteristics

Abstract The flow field of viscoelastic fluids is commonly analyzed by using constitutive equations. In this paper, a bead-spring-damper macro model with interaction is proposed as an alternative to analyze a viscoelastic flow. A tetrahedral structure of beads and springs models a gathering of intertwined polymer chains. Behavior of the macro model and the cluster is computed under a simple shear flow condition. Shear-thinning of viscosity, the mechanism of generation of normal stress differences and the effect of slip in the interaction are investigated. The results show that the elongation of clusters to the x direction is the mechanism of the normal stress differences generation, and that the slip in the interaction weakens the stresses. Consequently, it is found that the bead-spring-damper macro model can express the behavior of polymer chains in viscoelastic fluids and basic characteristics of viscoelastic fluids without using constitutive equations.

Rock friction under variable normal stress

2017 ◽  
Vol 122 (9) ◽  
pp. 7042-7075 ◽  
Author(s):  
Brian Kilgore ◽  
N. M. Beeler ◽  
Julian Lozos ◽  
David Oglesby
Keyword(s):  
Normal Stress ◽  
Rock Friction

scholarly journals Temperature dependence of ice-on-rock friction at realistic glacier conditions

2017 ◽  
Vol 375 (2086) ◽  
pp. 20150348 ◽  
Author(s):  
C. McCarthy ◽  
H. Savage ◽  
M. Nettles
Keyword(s):  
Steady State ◽  
Temperature Dependence ◽  
Normal Stress ◽  
Velocity Dependence ◽  
Ice Streams ◽  
Experimental Conditions ◽  
Rock Friction ◽  
Load Point ◽  
Basal Sliding ◽  
Temperature Dependences

Using a new biaxial friction apparatus, we conducted experiments of ice-on-rock friction in order to better understand basal sliding of glaciers and ice streams. A series of velocity-stepping and slide–hold–slide tests were conducted to measure friction and healing at temperatures between −20°C and melting. Experimental conditions in this study are comparable to subglacial temperatures, sliding rates and effective pressures of Antarctic ice streams and other glaciers, with load-point velocities ranging from 0.5 to 100 µm s −1 and normal stress σ n  = 100 kPa. In this range of conditions, temperature dependences of both steady-state friction and frictional healing are considerable. The friction increases linearly with decreasing temperature (temperature weakening) from μ  = 0.52 at −20°C to μ  = 0.02 at melting. Frictional healing increases and velocity dependence shifts from velocity-strengthening to velocity-weakening behaviour with decreasing temperature. Our results indicate that the strength and stability of glaciers and ice streams may change considerably over the range of temperatures typically found at the ice–bed interface. This article is part of the themed issue ‘Microdynamics of ice’.

Normal Stress Ratio Predicted by Viscoelastic Constitutive Equations.

2002 ◽  
Vol 30 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Takeharu Isaki, ◽  
Masaoki Takahashi
Keyword(s):  
Normal Stress ◽  
Constitutive Equations ◽  
Stress Ratio
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