Dry friction in the Frenkel-Kontorova-Tomlinson model: Static properties

Weiß, Michael; Elmer, Franz-Josef

doi:10.1103/physrevb.53.7539

Cited by 166 publications

(123 citation statements)

References 13 publications

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“…However, the values from the constant force simulations were smaller, i.e., about one-half of ‫ץ͑‬ int / ‫ץ‬x͉͒ max , as indicated in Table I. The reason for the simulated static friction being smaller than the maximum energy slope is related to the inertia effect 25 of the sliding slabs when overcoming the energy barrier. In the constant velocity simulations, the external force must always equal the friction force to maintain a constant velocity.…”

Section: Relationship Between Critical Shear Stress and Adhesionmentioning

confidence: 88%

“…In conclusion, ‫ץ͑‬ int / ‫ץ‬x͉͒ max gives the upper bound of the static friction, whereas static friction can be lower than ‫ץ͑‬ int / ‫ץ‬x͉͒ max , because of the inertia effect or sliding history. 25 The last question on the origin of static friction is how the energy barrier arises in the first place. This is an important question since the energy barrier is largely responsible for the atomic origin of static friction.…”

Section: Relationship Between Critical Shear Stress and Adhesionmentioning

confidence: 99%

See 1 more Smart Citation

Origin of static friction and its relationship to adhesion at the atomic scale

Zhang

Qi²,

Hector³

et al. 2007

Phys. Rev. B

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Using atomic scale interfaces consisting of slabs of the same materials, we study the relationship between adhesion and static friction. The work of separation, which is a measure of adhesion, and the spatial variation of the interface potential energy along the sliding direction are computed for both commensurate and incommensurate Al 2 O 3 /Al 2 O 3 interfaces, and incommensurate smooth and rough Al/ Al interfaces. These values are compared with the predicted static friction stress resulting from constant force and constant velocity molecular dynamics simulations. Simulation results show that static friction is not determined by the absolute value of adhesion. Rather, it is determined by the change of potential energy along the sliding direction.

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Section: Relationship Between Critical Shear Stress and Adhesionmentioning

confidence: 88%

Section: Relationship Between Critical Shear Stress and Adhesionmentioning

confidence: 99%

Origin of static friction and its relationship to adhesion at the atomic scale

Zhang

Qi²,

Hector³

et al. 2007

Phys. Rev. B

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“…The generic features of this behavior can be explained by the Frenkel-Kontorova-Tomlinson model. [12][13][14] Coupling between the lattice dynamics and the phonons of the two surfaces dominates the observed behavior. 15 Modelling friction has been able to help clarify the origins of these effects on the nanoscale and mesoscale.…”

Section: Introductionmentioning

confidence: 90%

Non-equilibrium phase behavior and friction of confined molecular films under shear: A non-equilibrium molecular dynamics study

Maćkowiak

Heyes

Dini

et al. 2016

The Journal of Chemical Physics

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The phase behavior of a confined liquid at high pressure and shear rate, such as is found in elastohydrodynamic lubrication, can influence the traction characteristics in machine operation.Generic aspects of this behavior are investigated here using Non-equilibrium Molecular Dynamics (NEMD) simulations of confined Lennard-Jones (LJ) films under load with a recently proposed wall-driven shearing method without wall atom tethering [Gattinoni, Maćkowiak, Heyes, Brańka and Dini, Phys. Rev. E 90, 043302 (2014)]. The focus is on thick films in which the nonequilibrium phases formed in the confined region impact on the traction properties. The nonequilibrium phase and tribological diagrams are mapped out in detail as a function of load, wall sliding speed and atomic scale surface roughness, which is shown can have a significant effect. The transition between these phases is typically not sharp as the external conditions are varied. The magnitude of the friction coefficient depends strongly on the nonequilibrium phase adopted by the confined region of molecules, and in general does not follow the classical friction relations between macroscopic bodies, e.g., the frictional force can decrease with increasing load in the Plug-Slip (PS) region of the phase diagram owing to structural changes induced in the confined film. The friction coefficient can be extremely low (∼ 0.01) in the PS region as a result of incommensurate alignment between a (100) face-centered cubic wall plane and reconstructed (111) layers of the confined region near the wall. It is possible to exploit hysteresis to retain low friction PS states well into the Central Localization high wall speed region of the phase diagram.Stick-Slip behavior due to periodic in-plane melting of layers in the confined region and subsequent annealing is observed at low wall speeds and moderate external loads. At intermediate wall speeds and pressure values (at least) the friction coefficient decreases with increasing well depth of the LJ potential between the wall atoms, but increases when the attractive part of the potential between wall atoms and confined molecules is made larger.2

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“…At this point there is an infinite number of different metastable ground states that form a fascinating "Devil's staircase" as η varies (Aubry, 1979(Aubry, , 1983Bak, 1982). Weiss and Elmer (1996) have performed a careful study of the 1D Frenkel-Kontorova-Tomlinson model where both types of springs are included. Their work illustrates how one can have a finite static friction at all rational η and an Aubry at all irrational η.…”

Section: B Metastability and Static Friction In One Dimensionmentioning

confidence: 99%

Computer Simulations of Friction, Lubrication, and Wear

Robbins¹,

Müser²

2000

Mechanics &Amp; Materials Science

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Computer simulations have played an important role in understanding tribological processes. They allow controlled numerical "experiments" where the geometry, sliding conditions and interactions between atoms can be varied at will to explore their effect on friction, lubrication, and wear. Unlike laboratory experiments, computer simulations enable scientists to follow and analyze the full dynamics of all atoms. Moreover, theorists have no other general approach to analyze processes like friction and wear. There is no known principle like minimization of free energy that determines the steady state of non-equilibrium systems. Even if there was, simulations would be needed to address the complex systems of interest, just as in many equilibrium problems.Tremendous advances in computing hardware and methodology have dramatically increased the ability of theorists to simulate tribological processes. This has led to an explosion in the number of computational studies over the last decade, and allowed increasingly sophisticated modeling of sliding contacts. Although it is not yet possible to treat all the length scales and time scales that enter the friction coefficient of engineering materials, computer simulations have revealed a great deal of information about the microscopic origins of static and kinetic friction, the behavior of boundary lubricants, and the interplay between molecular geometry and tribological properties. These results provide valuable input to more traditional macroscopic calculations. Given the rapid pace of developments, simulations can be expected to play an expanding role in tribology.In the following chapter we present an overview of the major results from the growing simulation literature. The emphasis is on providing a coherent picture of the field, rather than a historical review. We also outline opportunities for improved simulations, and highlight unanswered questions.We begin by presenting a brief overview of simulation techniques and focus on special features of simulations for tribological processes. For example, it is well known that the results of tribological experiments can be strongly influenced by the mechanical properties of the entire system that produces sliding. In much the same way, the results from simulations depend on how relative motion of the surfaces is imposed, and how heat generated by sliding is removed. The different techniques that are used are described, so that their influence on results can be understood in later sections.The complexities of realistic three-dimensional systems can make it difficult to analyze the molecular mechanisms that underly friction. The third section focuses on dry, wearless friction in less complex systems. The discussion begins with simple one-dimensional models of friction between crystalline surfaces. These models illustrate general results for the origin and trends of static and kinetic friction, such as the importance of metastability and the effect of commensurability. Then two-dimensional studies are described, with an emphasis ...

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Dry friction in the Frenkel-Kontorova-Tomlinson model: Static properties

Cited by 166 publications

References 13 publications

Origin of static friction and its relationship to adhesion at the atomic scale

Origin of static friction and its relationship to adhesion at the atomic scale

Non-equilibrium phase behavior and friction of confined molecular films under shear: A non-equilibrium molecular dynamics study

Computer Simulations of Friction, Lubrication, and Wear

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