Steady Sliding of Two Elastic Half-Spaces With Friction Reduction due to Interface Stick-Slip

1998 ◽  
Vol 65 (2) ◽  
pp. 470-475 ◽  
Author(s):  
G. G. Adams
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Dynamic Instability ◽  
Steady Motion ◽  
Friction Reduction ◽  
Stick Slip ◽  
Interface Friction ◽  
Stick Slip Motion ◽  
Frictional Slip ◽  
Slip Motion

The sliding of two perfectly flat elastic half-spaces with a constant interfacial coefficient of friction is investigated. Previous work has demonstrated that this configuration is dynamically unstable due to the destabilization of frictional slip waves. It was speculated that this dynamic instability could lead to stick-slip motion at the sliding interface. It is shown here that stick-slip motion at the interface can exist with a speed-independent interface coefficient of friction. Steady motion persists sufficiently far from the interface and thus gives the impression of uniform sliding. This type of stick-slip motion is due to interfacial slip waves and allows the bodies to slide with an apparent coefficient of friction which is less than the interface coefficient of friction. Furthermore it is shown that the apparent friction coefficient decreases with increasing speed even if the interface friction coefficient is speed-independent. Finally, it is shown that the presence of slip waves may make it possible for two frictional bodies to slide without a resisting shear stress and without any interface separation. No distinction is made between static and kinetic friction.

Studies on Friction and Formation of Transfer Layer in HCP Metals

2008 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas
Keyword(s):  
Coefficient Of Friction ◽  
Surface Texture ◽  
Soft Materials ◽  
Hard Material ◽  
Layer Formation ◽  
Ambient Conditions ◽  
Transfer Layer ◽  
Stick Slip ◽  
Stick Slip Motion ◽  
Slip Motion

Surface texture plays an important role as it predominantly controls the frictional behavior and transfer layer formation at the contacting surfaces. In the present investigation, basic studies were conducted using inclined pin-on-plate sliding tester to understand the role of surface texture of hard material on coefficient of friction and transfer layer formation when sliding against soft materials. HCP materials such as pure Mg and pure Zn were used as pins while 080 M40 steel was used as plate in the tests. Two surface parameters of steel plates — roughness and texture — were varied in the tests. Tests were conducted in ambient conditions under both dry and lubricated conditions. The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope. It was observed for both the pin materials that the occurrence of stick-slip motion, the transfer layer formation and the value of coefficient of friction as well as its two components, namely, adhesion and plowing, depend primarily on surface texture. The effect of surface texture on coefficient of friction was attributed to the variation of plowing component of friction for different surfaces. Both the plowing component of friction and amplitude of stick-slip motion were highest for the surface texture that promotes plane strain conditions while these were lowest for the texture that favors plane stress conditions at the interface.

scholarly journals Shearing of fibrillar adhesive microstructure: friction and shear-related changes in pull-off force

2007 ◽  
Vol 4 (15) ◽  
pp. 721-725 ◽  
Author(s):  
M Varenberg ◽  
S Gorb
Keyword(s):  
Friction Coefficient ◽  
Flat Surface ◽  
Stick Slip ◽  
Stick Slip Motion ◽  
Slip Motion

To characterize the effect of shearing on function of fibrillar adhesive microstructure, friction and shear-related changes in pull-off force of a biomimetic polyvinylsiloxane mushroom-shaped fibrillar adhesive microstructure were studied. In contrast to a control flat surface, which exhibited pronounced stick–slip motion accompanied with high friction, the fibrillar microstructure demonstrated a stable and smooth sliding with a friction coefficient approximately four times lower. The structured contact also manifested zero pull-off force in a sheared state, while the flat surface exhibited highly scattered and unreliable pull-off force when affected by contact shearing. It appears that the fibrillar microstructure can be used in applications where a total attachment force should be generated in a binary on/off state and, most surprisingly, is suitable to stabilize and minimize elastomer friction.

Rheology of a granular column

2000 ◽  
Vol 627 ◽  
Author(s):  
Evelyne Kolb ◽  
Guillaume Ovarlez ◽  
Pascal Sausse ◽  
Eric Clément
Keyword(s):  
Energy Release ◽  
Critical Velocity ◽  
Dynamic Instability ◽  
Vertical Cylinder ◽  
Resistance Force ◽  
Stick Slip ◽  
Aging Phenomena ◽  
Stick Slip Motion ◽  
Slip Motion ◽  
Granular Column

ABSTRACTWe study the rheology of a granular material in a confined geometry. The grains are stacked in a vertical cylinder and pushed at different driving velocities. The resistance force encountered by the bottom piston is monitored while the piston is pushing the granular column upwards. Above a critical velocity, the motion is characterized by a steady sliding and by a force level increasing rather slowly with the pushing velocity. For driving velocities under this threshold, the system undergoes a dynamic instability and then, a stick-slip motion occurs. The amplitude of the slipping events, and thus, the elastic energy release, increase strongly when the velocity decreases. The critical velocity depends on the stiffness of the driving system and on the height of the granular column. This transition can be shifted towards higher velocity values by increasing the friction at the walls of the cylinder. It is also very sensitive to the state of compaction of the grains. Moreover, the mean energy release during a stick-slip motion seems to increase as a power-law when the pushing velocity is decreased. We also show that the distribution of energy release is strongly dependent on the level of disorder in the grains (polydispersity, friction, etc.). We argue that this complex phenomenology characterizes confined granular packing in connection with arching and aging phenomena.

Adhesion and Friction of a Biomimetic Mushroom-Shaped Fibrillar Microstructure

2007 ◽  
Author(s):  
M. Varenberg ◽  
S. Gorb
Keyword(s):  
Friction Coefficient ◽  
Flat Surface ◽  
Synthetic Polymer ◽  
Control Surface ◽  
Adhesive Properties ◽  
Stick Slip ◽  
Stick Slip Motion ◽  
Slip Motion

Adhesion and friction of a novel biomimetic mushroom-shaped fibrillar microstructure were tested. The microstructure reveals approximately twice more effective adhesive properties than a control flat surface made of the same soft synthetic polymer. It also demonstrates smooth sliding with a friction coefficient approximately four times lower than that of the control surface which exhibits pronounced stick-slip motion. It appears that the new microstructure can be used in applications where a total attachment force needs to be generated in a binary on/off state and, most surprisingly, is suitable to stabilize and minimize elastomer friction.

Drag-Reduction and Resonance Problems of a Jointed Drillstring in the Presence of an Axial Excitation Tool

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Xueying Wang ◽  
Hongjian Ni ◽  
Ruihe Wang ◽  
Lei Zhang ◽  
Peng Wang
Keyword(s):  
Drag Reduction ◽  
Friction Reduction ◽  
Drill Bit ◽  
Frictional Drag ◽  
Stick Slip ◽  
Axial Excitation ◽  
Weight On Bit ◽  
Vibration Responses ◽  
Stick Slip Motion ◽  
Slip Motion

Axial excitation tools (AETs) have the ability to improve slide-drilling efficiency by reducing the friction between the drillstring and the wellbore wall. However, drag-reduction effects are not always satisfactory, and excessive vibration may cause failures of downhole tools in some cases. Thus, a mathematical model was proposed to simulate the vibration responses of a drillstring. In the model, velocity-dependent friction is adopted to calculate the friction-reduction effect. The effect of drillstring joints on the weight on bit (WOB) was first investigated. The simulation results indicate that the joints intensify the stick-slip motion of the drillstring system. The effect of the location of an AET was then examined. The results show that it is better to place an AET near the drill bit rather than near the rear of a build section. Because the frictional drag acting on the lower portion of the drillstring dominates the axial stick-slip motion of a drill bit. Finally, the resonance responses were examined in terms of the drillstring system acceleration. The results show that resonance moderately increases the accelerations of a long horizontal drillstring system in a heavy-damping environment but that the growth of the exciting force can profoundly increase the accelerations.

A Mobile Mechanism With Slant Leg on a Vibratory Floor

2001 ◽  
Author(s):  
Hideya Yamaguchi ◽  
Masahito Yashima
Keyword(s):  
Numerical Simulation ◽  
Friction Force ◽  
Coefficient Of Friction ◽  
Stick Slip ◽  
Main Mass ◽  
Rotational Spring ◽  
Exciting Frequency ◽  
The Difference ◽  
Stick Slip Motion ◽  
Slip Motion

Abstract This paper investigates the characteristics of a mobile mechanism that consists of a main mass and a slant leg with a rotational spring at the joint. The device travels on an oscillating floor due to the difference in the friction force between forward and backward directions during the stick-slip motion. Numerical simulation and experimentation show that the direction and velocity of movement are controlled by the exciting frequency. Furthermore, the effects of the angle of the slant leg and the sliding coefficient of friction on those characteristics are investigated.

Dynamics of stick–slip motion, Whillans Ice Stream, Antarctica

2011 ◽  
Vol 305 (3-4) ◽  
pp. 283-289 ◽  
Author(s):  
J. Paul Winberry ◽  
Sridhar Anandakrishnan ◽  
Douglas A. Wiens ◽  
Richard B. Alley ◽  
Knut Christianson
Keyword(s):  
Stick Slip ◽  
Ice Stream ◽  
Whillans Ice Stream ◽  
Stick Slip Motion ◽  
Slip Motion

Dynamic simulation of stick–slip motion of a flexible solar array

2008 ◽  
Vol 16 (6) ◽  
pp. 724-735 ◽  
Author(s):  
Yasushi Kojima ◽  
Shigemune Taniwaki ◽  
Yoshiaki Okami
Keyword(s):  
Dynamic Simulation ◽  
Solar Array ◽  
Stick Slip ◽  
Stick Slip Motion ◽  
Slip Motion

scholarly journals Basal ice motion and deformation at the ice-sheet margin, West Greenland

2005 ◽  
Vol 42 ◽  
pp. 67-70 ◽  
Author(s):  
David M. Chandler ◽  
Richard I. Waller ◽  
William G. Adam
Keyword(s):  
Deformation Mode ◽  
Time Intervals ◽  
Stick Slip ◽  
Active Deformation ◽  
West Greenland ◽  
Shear Structures ◽  
Basal Ice ◽  
Ice Velocity ◽  
Stick Slip Motion ◽  
Slip Motion

AbstractMeasurements of basal ice deformation at the margin of Russell Glacier, West Greenland, have provided an opportunity to gain more insight into basal processes occurring near the margin. The basal ice layer comprises a debris-rich, heterogeneous stratified facies, overlain by a comparatively debris-poor dispersed facies. Ice velocities were obtained from anchors placed in both ice facies, at three sites under 5–15 m ice depth. Mean velocities ranged from 20 to 43 m a–1, and velocity gradients indicate high shear strain rates within the basal ice. Stick–slip motion and diurnal variations were observed during measurements at short (1–5 min) time intervals. Vertical gradients in horizontal ice velocity indicate two modes of deformation: (1) viscous deformation within the stratified ice facies, and (2) shear at the interface between the two basal ice facies. Deformation mode 1 may contribute to the folding and shear structures observed in the stratified facies. Deformation mode 2 may generate the stick–slip motion and be associated with the formation of debris bands. Active deformation close to the margin suggests that structures observed within the basal ice are only partially representative of processes occurring near the bed in areas away from the glacier margin.

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