Suppression of Friction by Mechanical Vibrations

Abstract

Mechanical vibrations are known to affect frictional sliding and the associated stick-slip patterns causing sometimes a drastic reduction of the friction force. This issue is relevant for applications in nanotribology and to understand earthquake triggering by small dynamic perturbations . We study the dynamics of repulsive particles confined between a horizontally driven top plate and a vertically oscillating bottom plate. Our numerical results show a suppression of the high dissipative stick-slip regime in a well defined range of frequencies that depends on the vibrating amplitude, the normal applied load, the system inertia and the damping constant. We propose a theoretical explanation of the numerical results and derive a phase diagram indicating the region of parameter space where friction is suppressed. Our results allow to define better strategies for the mechanical control of friction.PACS numbers: 81.40. Pq, 46.55.+d, 68.35.Af, Natural or artificially induced manipulations by small mechanical vibrations, when applied at suitable frequency and amplitude ranges, may help in driving a contacting sliding interface out of its potential energy minima, thus increasing considerably surface mobility and diffusion, and reducing friction. This has been shown experimentally for sliding of nanoscale contacts through, e.g., the atomic force microscope [1,2,3], and in computer simulations via extended molecular dynamics [4] and simple modeling approaches [5,6,7]. On a larger scale, it has been observed that in sheared granular media experiments the stick slip behavior is significantly perturbed by tiny transverse vibrations [8,9]. Since geological faults are often filled with a granular gouge, these results might be relevant to understand earthquake triggering by low amplitude seismic waves [10]. Despite these promising numerical and experimental contributions, a quantitative theory accounting for the friction dependence on vibrations is still lacking.In this letter, we study the frictional properties of a two dimensional set of repulsive particles confined between two rigid plates (see Fig.1) [11,12]. The top plate is attached to a spring that is pulled at constant velocity, while the bottom FIG. 1: Sketch of the system, with the rigid top and bottom plates indicated in black and the confined particles in red. The top is dragged through a spring of elastic constant K moving at constant velocity Vext, while the bottom vibrates vertically with frequency ω0 and amplitude A plate is vibrated vertically. Without vibration, the top plate would slide exhibiting a characteristic stick-slip behavior. Vibrations induce a drastic reduction of the friction coefficient and a suppression of the stick-slip behavior, but only in a well defined frequency range. We propose a theoretical argument to explain this behavior and construct a phase diagram indicating the parameter region for which friction is suppressed. The theoretical results are in excellent quantitative agreement with numerical simulations. Finally, we investigate the fr...

Effect of boundary vibration on the frictional behavior of a dense sheared granular layer

“…The intrinsic stick-slip dynamics of a granular layer can be perturbed by external factors including boundary vibrations. Laboratory scale observations as well as Discrete Element Method (DEM) simulations show and confirm that mechanical and acoustic vibrations with adequate amplitudes can change the mechanical and frictional properties of a confined and sheared granular layer, and consequently its macro-scale response [6,7,8,9,10,11,12]. Many aspects of this vibration-induced changes including its grain-scale mechanisms, its dependence on the loading state of the granular layer and on the vibration amplitude are unexplored.…”

Effect of Surface Roughness on the Stick-slip Behavior of Magnetic Field Controlled-dipolar Suspensions in Simple Linear Shear Mode

“…Various factors [3][4] have great impact on the process of accumulating energy in "stick" part while releasing the energy in "slip" part when the two surfaces rubbing together. Research concerns more about the properties and mechanisms of the stick-slip motion due to the characterization of the materials and some focus on controlling and modulations [5,6]. Mechanical properties of electrorheological(ER) and magnetorheological (MR) fluids can be dramatically changed once exposed to the external electric/magnetic field [7,8].…”

Stochastic Modeling and Rate Theory of Atomic Friction

“…In the context of the model, in the first case the support position is affected by a shaking term. For out-of-plane actuation, the tip-substrate potential amplitude is modulated by an oscillating term [76], or the tip-sample distance is taken explicitly into account with a corresponding modification of the tip potential [72]. As in the regular case, thermal fluctuations are incorporated in the model as an additive Gaussian noise.…”

“…Ultrasonic vibrations have been proposed as a valid method for reducing friction at the nanoscale [72][73][74][75][76][77]. The PT model can be useful to study the dynamics of the system in the presence of in-plane and out-of-plane actuation fields.…”