Stabilization of Frictional Sliding by Normal Load Modulation

2003 ◽  
Vol 70 (2) ◽  
pp. 220-226 ◽  
Author(s):  
A. Cochard ◽  
L. Bureau ◽  
T. Baumberger
Keyword(s):  
Normal Load ◽  
Modulation Frequency ◽  
Shear Stiffness ◽  
Quantitative Agreement ◽  
Stability Diagram ◽  
Polymer Materials ◽  
Stick Slip ◽  
Classical State ◽  
Rate Dependent ◽  
Frictional System

This paper presents the stability analysis of a system sliding at low velocities (<100 μm⋅s−1) under a periodically modulated normal load, preserving interfacial contact. Experiments clearly evidence that normal vibrations generally stabilize the system against stick-slip oscillations, at least for a modulation frequency much larger than the stick-slip one. The mechanical model of L. Bureau, T. Baumberger, and C. Caroli validated on the steady-state response of the system, is used to map its stability diagram. The model takes explicitly into account the finite shear stiffness of the load-bearing asperities, in addition to a classical state and rate-dependent friction force. The numerical results are in excellent quantitative agreement with the experimental data obtained from a multicontact frictional system between glassy polymer materials. Simulations at larger amplitude of modulation (typically 20 percent of the mean normal load) suggest that the nonlinear coupling between normal and sliding motion could have a destabilizing effect in restricted regions of the parameter space.

Intra-sonic propagation of sliding zones in a fault

2020 ◽  
Author(s):  
Arcady Dyskin ◽  
Elena Pasternak
Keyword(s):  
Shear Crack ◽  
Propagation Speed ◽  
Shear Stiffness ◽  
Telegraph Equation ◽  
P Wave ◽  
Plane Shear ◽  
Stick Slip ◽  
Frictional Sliding ◽  
Rate Dependent ◽  
Sliding Zone

&lt;p&gt;Seismic events associated with pre-existing faults are traditionally assumed to be caused by rupture propagation, that is in-plane shear crack propagation. However what appears to be a shear crack is a sliding zone over a fault; it grows by overcoming friction (either in direct contact or in the gouge) rather than rock rupture. When modelling frictional sliding, two important factors need to be considered: (1) the elasticity of the surrounding rocks which causes self-oscillations resulting in the movement resembling stick-slip even in constant friction; (2) the rotation of real gouge particles which being non-spherical lead, in the presence of compression, to the effect of negative shear stiffness. The latter effectively works to transfer the elastic energy stored in the compressed rock into the energy of the sliding zone propagation.&lt;/p&gt;&lt;p&gt;This presentation introduces 1D models accounting for these factors. Both lead to the so-called telegraph equation which is a wave equation with a non-derivative term referring to the fact that the movement is considered against a stationary solid. The equation with respect to displacement corresponds to the case of apparent negative stiffness, while the equation with respect to the displacement rate corresponds to the pure frictional sliding. The rock elasticity leads to the sliding zone propagation speed equal to the p-wave velocity making the propagation speed intra-sonic [1]. The rate-dependent friction can slightly reduce the speed. It is interesting that the sliding zone propagation is related to p-wave rather than s- or Raylegh waves as one would anticipate. The results of this research contribute to the understanding of the mechanics of seismicity.&lt;/p&gt;&lt;ol&gt;&lt;li&gt;Karachevtseva, I, A.V. Dyskin and E. Pasternak, 2017. Generation and propagation of stick-slip waves over a fault with rate-independent friction. Nonlinear Processes in Geophysics (NPG), 24, 343-349.&lt;/li&gt; &lt;/ol&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;. AVD acknowledges the support from the School of Civil and Transportation, Faculty of Engineering, Beijing University of Civil Engineering and Architecture.&lt;/p&gt;

Motion of masses with asymmetric and symmetric friction. Application to fault sliding

2021 ◽  
Author(s):  
Rui Xiang Wong ◽  
Elena Pasternak ◽  
Arcady Dyskin
Keyword(s):  
Frictional Force ◽  
Normal Load ◽  
Power Spectra ◽  
Inertial Force ◽  
Friction Reduction ◽  
Relative Mass ◽  
Hydraulic Fractures ◽  
Driving Frequency ◽  
Stick Slip ◽  
Friction Forces

&lt;p&gt;This study analyses a situation when a geological fault contains a section of anisotropic gouge with inclined symmetry axes (e.g. inclined layering), Bafekrpour et al. [1]. Such gouge in a constrained environment induces, under compression, asymmetric friction (different friction forces resisting sliding in the opposite directions). The rest of the gouge produces conventional symmetric friction. A mass-spring model of the gouge with asymmetric and symmetric friction sections is proposed consisting of a mass with asymmetric friction connected through a spring to another mass with symmetric friction. These masses are set on a base subjected to vibration. A parametric analysis is performed on this system. Two distinct characteristic regimes were observed: &lt;em&gt;recurrent movement&lt;/em&gt; resembling stick-slip motion similar to predicted by [2] and &lt;em&gt;sub-frictional movement&lt;/em&gt;. Recurrent movement arises when the inertial force is sufficient to overcome frictional force of a block with symmetric friction. Sub-frictional movement occurs when the inertial force is not sufficient to overcome frictional force of an equivalent system with only symmetric friction. The sub-frictional movement is produced by the force in the connecting spring increased due to the movement of the asymmetric friction block in the direction characterised by low friction. We formulate the criterion at which sub-frictional movement occurs. The occurrence of sub-frictional depends upon the relative mass of the symmetric and asymmetric friction sections, as well as the amplitude and driving frequency of the excitation. Power spectra of the produced vibrations are determined for both regimes. The results can shed light on mechanisms of sliding over pre-existing discontinuities and their effect on seismic event generation and propagation of hydraulic fractures in the presence of discontinuities.&lt;/p&gt;&lt;p&gt;[1] Bafekrpour,&lt;strong&gt; &lt;/strong&gt;E., A.V. Dyskin, E. Pasternak, A. Molotnikov and Y. Estrin (2015), Internally architectured materials with directionally asymmetric friction. &lt;em&gt;Scientific Reports&lt;/em&gt;, 5, Article 10732.&lt;/p&gt;&lt;p&gt;[2] Pasternak, E. A.V. Dyskin and I. Karachevtseva, 2020. Oscillations in sliding with dry friction. Friction reduction by imposing synchronised normal load oscillations. &lt;em&gt;International Journal of Engineering Science&lt;/em&gt;, 154, 103313.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgement&lt;/strong&gt;. AVD and EP acknowledge support from the Australian Research Council through project DP190103260.&lt;/p&gt;

scholarly journals Experimental Study on the Transition between Static and Kinetic Frictions of Steel/Shale Pairs

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qin Lian ◽  
Chunxu Yang ◽  
Jifei Cao
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Critical Distance ◽  
Dynamic Friction ◽  
Stick Slip ◽  
Dynamic Friction Coefficient ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Stick Slip Motion ◽  
Insight Into

The transition between static and kinetic frictions of steel/shale pairs has been studied. It was found that the coefficient of friction decreased exponentially from static to dynamic friction coefficient with increasing sliding displacement. The difference between static and dynamic friction coefficients and the critical distance Dc under the dry friction condition is much larger than that under the lubricated condition. The transition from static to dynamic friction coefficient is greatly affected by the normal load, quiescent time, and sliding velocity, especially the lubricating condition. Maintaining continuous lubrication of the contact area by the lubricant is crucial to reduce or eliminate the stick-slip motion. The results provide an insight into the transition from static to dynamic friction of steel/shale pairs.

scholarly journals High-Velocity Shear and Soft Friction at the Nanometer Scale

2021 ◽  
Vol 7 ◽  
Author(s):  
Per-Anders Thorén ◽  
Riccardo Borgani ◽  
Daniel Forchheimer ◽  
David B. Haviland
Keyword(s):  
High Speed ◽  
Surface Deformation ◽  
Soft Materials ◽  
Lateral Force ◽  
Velocity Shear ◽  
Polymer Materials ◽  
Amplitude Dependence ◽  
Dynamic Force ◽  
Stick Slip ◽  
Soft Polymer

We study high-speed friction on soft polymer materials by measuring the amplitude dependence of cyclic lateral forces on the atomic force microscope (AFM) tip as it slides on the surface with fixed contact force. The resulting dynamic force quadrature curves separate the elastic and viscous contributions to the lateral force, revealing a transition from stick-slip to free-sliding motion as the velocity increases. We explain force quadratures and describe how they are measured, and we show results for a variety of soft materials. The results differ substantially from the measurements on hard materials, showing hysteresis in the force quadrature curves that we attribute to the finite relaxation time of viscoelastic surface deformation.

Characterization of Cofficient of Friction in Dry Contact for Control of Vibrations in Machine Systems

2000 ◽  
Author(s):  
Jamil Abdo ◽  
Kambiz Farhang ◽  
Glenn Meinhardt
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Normal Load ◽  
304 Stainless Steel ◽  
Stick Slip ◽  
Dry Contact ◽  
Machine Systems ◽  
Alloy 6061

Abstract A 2k factorial experiment is performed to ascertain the effect of four factors and their cross influence on friction between dry surfaces. The factors in this study include materials Young’s modulus, applied normal load, surface roughness and relative surface speed. For each combination of factors four replicates in addition to two center points are used to obtain an average coefficient of friction for dry contact. In the experiment 304 Stainless Steel and Alloy 6061 Aluminum are employed to provide the high and low levels of Young’s modulus. Results suggest that Young’s modulus has the most significant influence followed by velocity/modulus cross-coupling, surface roughness, load, and modulus/roughness. Analyses are carried out separately for the 304 Stainless Steel and alloy 6061 Aluminum to remove the effect of Young’s modulus. The results are used to obtain iso-friction curves that serve to establish force-speed control for prevention of stick-slip vibration.

scholarly journals Finger pad friction and its role in grip and touch

2013 ◽  
Vol 10 (80) ◽  
pp. 20120467 ◽  
Author(s):  
Michael J. Adams ◽  
Simon A. Johnson ◽  
Philippe Lefèvre ◽  
Vincent Lévesque ◽  
Vincent Hayward ◽  
...  
Keyword(s):  
Contact Zone ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Theoretical Models ◽  
Tactile Perception ◽  
Major Influence ◽  
Sliding Velocity ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Finger Pad

Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick–slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.

Numerical Modeling of Friction-Induced Vibrations and Dynamic Instabilities

1994 ◽  
Vol 47 (7) ◽  
pp. 255-274 ◽  
Author(s):  
W. W. Tworzydlo ◽  
E. B. Becker ◽  
J. T. Oden
Keyword(s):  
Numerical Study ◽  
Normal Modes ◽  
Friction Model ◽  
Rigid Bodies ◽  
Stick Slip ◽  
Quantitative Correlation ◽  
Frictional System ◽  
Pin On Disk ◽  
Stick Slip Motion ◽  
Slip Motion

A numerical study of dynamic instabilities and vibrations of mechanical systems with friction is presented. Of particular interest are friction-induced vibrations, self-excited oscillations and stick-slip motion. A typical pin-on-disk apparatus is modeled as the assembly of rigid bodies with elastic connections. An extended version of the Oden-Martins friction model is used to represent properties of the interface. The mechanical model of the frictional system is the basis for numerical analysis of dynamic instabilities caused by friction and of self-excited oscillations. Coupling between rotational and normal modes is the primary mechanism of resulting self-excited oscillations. These oscillations combine with high-frequency stick-slip motion to produce a significant reduction of the apparent kinetic coefficient of friction. As a particular study model, a pin-on-disk experimental setup has been selected. A good qualitative and quantitative correlation of numerical and experimental results is observed.

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