Studies of columns of beads under external vibrations

Luding, Stefan; Clément, Éric; Blumen, A.; Rajchenbach, Jean; Duran, J.

doi:10.1103/physreve.49.1634

Cited by 211 publications

(164 citation statements)

References 27 publications

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“…The restitution coefficient r is the ratio between the relative normal velocities before and after impact. In contrast to most previous numerical studies of vibrated granular media [7,8,9], we let it depend on impact velocity. In most simulations of strongly vibrated granular media, the coefficient of restitution is considered to be constant and lower than 1.…”

Section: The Variable Coefficient Of Restitutionmentioning

confidence: 99%

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

McNamara

Falcon

2008

Powder Technology

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We report two-dimensional simulations of strongly vibrated granular materials without gravity. The coefficient of restitution depends on the impact velocity between particles by taking into account both the viscoelastic and plastic deformations of particles, occurring at low and high velocities respectively. Use of this model of restitution coefficient leads to new unexpected behaviors. When the number of particles N is large, a loose cluster appears near the fixed wall, opposite the vibrating wall. The pressure exerted on the walls becomes independent of N , and linear in the vibration velocity V , quite as the granular temperature. The collision frequency at the vibrating wall becomes independent of both N and V , whereas at the fixed wall, it is linear in both N and V . These behaviors arise because the velocity-dependent restitution coefficient introduces a new time scale related to the collision velocity near the cross over from viscoelastic to plastic deformation.

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Section: The Variable Coefficient Of Restitutionmentioning

confidence: 99%

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

McNamara

Falcon

2008

Powder Technology

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“…The Hertz and linear models are given by β = 1/2 and β = 0, respectively [22,26,37]. Choosing a length scale˜ (to be determined later), we scale the particle overlap:…”

Section: Compressed Chainmentioning

confidence: 99%

Frequency filtering in disordered granular chains

Lawney¹,

Luding²

2014

Acta Mech

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The study of disorder-induced frequency filtering is presented for one-dimensional systems composed of random, pre-stressed masses interacting through both linear and nonlinear (Hertzian) repulsive forces. An ensemble of such systems is driven at a specified frequency, and the spectral content of the propagated disturbance is examined as a function of distance from the source. It is shown that the transmitted signal contains only low-frequency components, and the attenuation is dependent on the magnitude of disorder, the input frequency, and the contact model. It is found that increased disorder leads to a narrower bandwidth of transmitted frequencies at a given distance from the source and that lower input frequencies exhibit less sensitivity to the arrangement of the masses. Comparison of the nonlinear and linear contact models reveals qualitatively similar filtering behavior; however, it is observed that the nonlinear chain produces transmission spectrums with a greater density at the lowest frequencies. In addition, it is shown that random masses sampled from normal, uniform, and binary distributions produce quantitatively indistinguishable filtering behavior, suggesting that knowledge of only the distribution's first two moments is sufficient to characterize the bulk signal transmission behavior. Finally, we examine the wave number evolution of random chains constrained to move between fixed end-particles and present a transfer matrix theory in wave number space, and an argument for the observed filtering based on the spatial localization of the higher-frequency normal modes.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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We report results of 3D Discrete Element Method (DEM) simulations aiming at investigating the role of the boundary vibration in inducing frictional weakening in sheared granular layers. We study the role of different vibration amplitudes applied at various shear stress levels, for a granular layer in the stick-slip regime and in the steady-sliding regime. Results are reported in terms of friction drops and kinetic energy release associated with frictional weakening events. We find that larger vibration amplitude induces larger frictional weakening events. The results show evidence of a threshold below which no induced frictional weakening takes place. Friction drop size 2 is found to be dependent on the shear stress at the time of vibration. A significant increase in the ratio between the number of slipping contacts to the number of sticking contacts in the granular layer is observed for large vibration amplitudes. These vibration-induced contact rearrangements enhance particle mobilization and induces a friction drop and kinetic energy release. This observation provides some insight into the grain-scale mechanisms of frictional weakening by boundary vibration in a dense sheared granular layer. In addition to characterizing the basic physics of vibration induced shear weakening, we are attempting to understand how a fault fails in the earth under seismic wave forcing. This is the well know phenomenon of dynamic earthquake triggering. We believe that the granular physics are key to this understanding.

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Studies of columns of beads under external vibrations

Cited by 211 publications

References 27 publications

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

Frequency filtering in disordered granular chains

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

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