On the random aspect of intermittent stick/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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Monitoring Stick-Slip Motion of Machine Tool Slides using Feed Motor Current

10.1109/imc.1990.687390 ◽

2005 ◽

Author(s):

J.L. Stein ◽

Wei Wu

Keyword(s):

Machine Tool ◽

Stick Slip ◽

Motor Current ◽

Stick Slip Motion ◽

Slip Motion

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Experimental Exploration of Schallamach Waves and Self-Excitation in a Belt-Drive System

Volume 6: 14th International Conference on Multibody Systems, Nonlinear Dynamics, and Control ◽

10.1115/detc2018-85894 ◽

2018 ◽

Author(s):

Yingdan Wu ◽

Michael Varenberg ◽

Michael J. Leamy

Keyword(s):

Angular Velocity ◽

Dynamic Behavior ◽

Oscillation Amplitude ◽

Operating Conditions ◽

Drive System ◽

Belt Drive ◽

Stick Slip ◽

Stick Slip Motion ◽

System Inertia ◽

Slip Motion

We study the dynamic behavior of a belt-drive system to explore the effect of operating conditions and system moment of inertia on the generation of waves of detachment (i.e., Schallamach waves) at the belt-pulley interface. A self-excitation phenomenon is reported in which frictional fluctuations serve as harmonic forcing of the pulley, leading to angular velocity oscillations which grow in time. This behavior depends strongly on operating conditions (torque transmitted and pulley speed) and system inertia, and differs between the driver and driven pulleys. A larger net torque applied to the pulley generally yields more remarkable stick-slip oscillations with higher amplitude and lower frequency. Higher driving speeds accelerate the occurrence of stick-slip motion, but have little influence on the oscillation amplitude. Contrary to our expectations, the introduction of flywheels to increase system inertia amplified the frictional disturbances, and hence the pulley oscillations. This does, however, suggest a way of facilitating their study, which may be useful in follow-on research.

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