Solid-on-solid single-block dynamics under mechanical vibration

Giacco, Ferdinando; Lippiello, Eugenio; Ciamarra, Massimo Pica

doi:10.1103/physreve.86.016110

Cited by 12 publications

(22 citation statements)

References 33 publications

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“…Discussion -Numerical models for solid friction under vertical vibrations predicted a transition between stickslip and continuous sliding motion governed by the vibration acceleration, with a threshold at Aω 2 g, the gravitational acceleration [19]. The above results demonstrate that, as previously shown in granular assemblies, the vibration velocity, and not acceleration, is the parameter controlling the transition.…”

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confidence: 71%

Friction weakening by mechanical vibrations: A velocity-controlled process

et al. 2019

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Frictional weakening by vibrations was first invoked in the 70's to explain unusual fault slips and earthquakes, low viscosity during the collapse of impact craters or the extraordinary mobility of sturzstroms, peculiar rock avalanches which travels large horizontal distances. This mechanism was further invoked to explain the remote triggering of earthquakes or abnormally large landslides or pyroclastic flows runout. Recent experimental and theoretical work pointed out the velocity of vibration as the key parameter which governs frictional weakening in sheared granular media. Here we show that the grains mobility is not mandatory, and that the vibration velocity governs both granular and solid frictional weakening. The velocity threshold controlling the transition from stickslip motion to continuous sliding is of the same order of magnitude, namely a hundred microns per second. It is linked to the roughness distribution of the asperities at the contact surface."It is easier to further the motion of a moving body than to move a body at rest." This sentence written by Themistius (about A.D. 320-390) is the first record of friction in history [1]. Since then, the frictional motion of a single body over a fixed substrate or of a sheared granular assembly revealed a wide variety of behaviors. At low shear velocity, the system experiences a stick-slip motion, with the alternance of loading phases (system at rest) and quick slip phases which release the energy. When increasing the shear velocity, a transition to continuous sliding motion is reported [2][3][4][5]. During catastrophic events such as earthquakes, landslides or pyroclastic flow, puzzling phenomena of frictional weakening were reported [6-9]: friction decreases with the shear velocity. Melosh [10] first proposed in 1979 that vibrations due to particle collisions could temporarily reduce the normal stress, and thus decrease the shear stress threshold to trigger sliding motion [11]. This mechanism, initially called vibrational fluidization and later on acoustic fluidization [10,11], was further sought to be at the origin of dramatic events triggered by external waves, such as earthquake remote triggering [8,12].How does endogenous noise or external mechanical disturbances drastically affect the frictional properties? Many works have attempted to tackle this issue for the last decades. They have shown that vibrations reduce or even suppress friction [13][14][15][16][17][18][19][20][21]. Interpretations were proposed based on a non-monotonic rheology curve, leading to instabilities and self-fluidization [22,23], softening effect due to non-linearity at the grains contact [24], contact opening [25,26] or sliding [27]. In single-block solid friction models, the vibration acceleration has often been stated at the parameter governing the transition between stick-slip motion and continuous sliding, with a threshold equal to the gravitational acceleration [19]. In a recent work, Lastakowski et al. [21] pointed out that the vibration velocity, and not the acceleration,...

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confidence: 71%

Friction weakening by mechanical vibrations: A velocity-controlled process

et al. 2019

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“…Other approaches to friction control include e.g. applying mechanical oscillations [10,11]. While the effect of wettability on lubricated friction has been studied experimentally in macroscopic [12][13][14][15] and nanoscale [16] systems, and modeled using phenomenological finite-element models [17] and simplified molecular dynamics (MD) simulations of nanopatterned surfaces [18,19], less is known about the underlying atomic scale processes and mechanisms responsible for the presence or absence of stick-slip.Given the large surface-to-volume ratio in boundary lubrication, nature of the interaction between the lubricant and the confining surfaces originating from their atomic composition should play a crucial role.…”

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confidence: 99%

Stick-Slip Control in Nanoscale Boundary Lubrication by Surface Wettability

et al. 2015

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We study the effect of atomic scale surface-lubricant interactions on nanoscale boundarylubricated friction, by considering two example surfaces -hydrophilic mica and hydrophobic graphene -confining thin layers of water in molecular dynamics simulations. We observe stickslip dynamics for thin water films confined by mica sheets, involving periodic breaking-reforming transitions of atomic scale capillary water bridges formed around the potassium ions of mica. However, only smooth sliding without stick-slip events is observed for water confined by graphene, as well as for thicker water layers confined by mica. Thus, our results illustrate how atomic scale details affect the wettability of the confining surfaces, and consequently control the presence or absence of stick-slip dynamics in nanoscale friction.

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“…Consistently, numerical investigations have also demonstrated that vibrations can advance the time of slip instability [16,17]. Other studies have identified a frequency regime leading to friction reduction [18,19] caused the detachment of the particles from the vibrating confining planes and not related to the fluidization of the granular bed.Here we validate the AF scenario through the numerical investigation of a model system. First we show that perturbations at a characteristic resonant frequency are able to activate acoustic modes inside the fault, promoting the entire system fluidization.…”

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confidence: 76%

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confidence: 76%

Dynamic Weakening by Acoustic Fluidization during Stick-Slip Motion

et al. 2015

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The unexpected weakness of some faults has been attributed to the emergence of acoustic waves that promote failure by reducing the confining pressure through a mechanism known as acoustic fluidization, also proposed to explain earthquake remote triggering. Here we validate this mechanism via the numerical investigation of a granular fault model system. We find that the stick-slip dynamics is affected only by perturbations applied at a characteristic frequency corresponding to oscillations normal to the fault, leading to gradual dynamical weakening as failure is approaching. Acoustic waves at the same frequency spontaneously emerge at the onset of failure in absence of perturbations, supporting the relevance of acoustic fluidization in earthquake triggering.

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Solid-on-solid single-block dynamics under mechanical vibration

Cited by 12 publications

References 33 publications

Friction weakening by mechanical vibrations: A velocity-controlled process

Friction weakening by mechanical vibrations: A velocity-controlled process

Stick-Slip Control in Nanoscale Boundary Lubrication by Surface Wettability

Dynamic Weakening by Acoustic Fluidization during Stick-Slip Motion

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