Why Do Granular Materials Stiffen with Shear Rate? Test of Novel Stress-Based Statistics

Behringer, Robert; Bi, Dapeng; Chakraborty, Bulbul; Henkes, Silke; Hartley, R. R.

doi:10.1103/physrevlett.101.268301

Cited by 49 publications

(54 citation statements)

References 19 publications

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“…The maximum value of the velocity spikes is always below V = 0.025, indicating that the probe particle is always in contact with the surrounding particles and never moves freely. The increasing intermittency is similar in appearance to the stress fluctuations seen in shear experiments [24]. Figure 6(b) shows a blowup of a velocity spike from Fig.…”

Section: Velocity Fluctuations Below Jammingsupporting

confidence: 69%

Fluctuations, jamming, and yielding for a driven probe particle in disordered disk assemblies

Reichhardt

2010

Phys. Rev. E

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Using numerical simulations we examine the velocity fluctuations of a probe particle driven with constant force through a two-dimensional disordered assembly of disks which has a well defined jamming point J at a density of φJ = 0.843. As φ increases toward φJ , the average velocity of the probe particle decreases and the velocity fluctuations show an increasingly intermittent or avalanchelike behavior. When the system is within a few percent of the jamming density, the velocity distributions are exponential, while when the system is less than a percent away from jamming, the velocity distributions have a non-exponential or power law character. The velocity power spectra exhibit a crossover from a Lorentzian form to a 1/f shape near jamming. We extract a correlation length exponent ν which is in good agreement with recent shear simulations. For φ > φJ , there is a critical threshold force Fc that must be applied for the probe particle to move through the sample which increases with increasing φ. The onset of the probe motion above φJ occurs via a local yielding of the particles around the probe particle which we term a local shear banding effect.

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Section: Velocity Fluctuations Below Jammingsupporting

confidence: 69%

Fluctuations, jamming, and yielding for a driven probe particle in disordered disk assemblies

Reichhardt

2010

Phys. Rev. E

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“…In the inertial regime, a constitutive law obtained in numerical simulation quantitatively explains the experimental observation on an inclined plane flow [5]. However, we have not reached the consensus about a constitutive law for the quasistatic regime [6,7,8]. Although some numerical studies [2,9,10,11] are conducted down to I ∼ 10 −5 to address a constitutive law for the quasistatic regime, they are yet to be verified in experiments.…”

Section: Introductionmentioning

confidence: 77%

Granular friction in a wide range of shear rates

Kuwano¹,

Ando²,

Hatano³

2013

AIP Conference Proceedings

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Abstract. We conduct an experiment on the frictional properties of granular matter over a wide range of shear rate that covers both the quasistatic and the inertial regimes. We show that the friction coefficient exhibits negative shear-rate dependence in the quasistatic regime, whereas the shear-rate dependence is positive in the inertial regime. The crossover shear rate is determined in terms of the competition between two physical processes, namely frictional healing and anelasticity. We confirm that these results are independent of the grain shape by using angular sand and spherical beads. We also show that the behavior in the inertial regime is quantitatively the same as that in numerical simulations. As an application, we derive the exponential velocity profiles that are often observed in the quasistatic heap flow.

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“…A angoricity-based, SGR-like framework has been used to analyze stress fluctuations in laboratory granular Couette flows [7,12]. This formalism provides an explanation for the observed logarithmic strengthening [44] of granular materials.…”

Section: Application To Dynamicsmentioning

confidence: 99%

The Statistical Physics of Athermal Materials

Henkes

Daniels

et al. 2015

Annu. Rev. Condens. Matter Phys.

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139

140

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At the core of equilibrium statistical mechanics lies the notion of statistical ensembles: a collection of microstates, each occurring with a given a priori probability that depends only on a few macroscopic parameters such as temperature, pressure, volume, and energy. In this review article, we discuss recent advances in establishing statistical ensembles for athermal materials. The broad class of granular and particulate materials is immune from the effects of thermal fluctuations because the constituents are macroscopic. In addition, interactions between grains are frictional and dissipative, which invalidates the fundamental postulates of equilibrium statistical mechanics. However, granular materials exhibit distributions of microscopic quantities that are reproducible and often depend on only a few macroscopic parameters. We explore the history of statistical ensemble ideas in the context of granular materials, clarify the nature of such ensembles and their foundational principles, highlight advances in testing key ideas, and discuss applications of ensembles to analyze the collective behavior of granular materials.

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Why Do Granular Materials Stiffen with Shear Rate? Test of Novel Stress-Based Statistics

Cited by 49 publications

References 19 publications

Fluctuations, jamming, and yielding for a driven probe particle in disordered disk assemblies

Fluctuations, jamming, and yielding for a driven probe particle in disordered disk assemblies

Granular friction in a wide range of shear rates

The Statistical Physics of Athermal Materials

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