Shear strength and force transmission in granular media with rolling resistance

Estrada, Nicolás; Taboada, Alfredo; Radjaï, Farhang

doi:10.1103/physreve.78.021301

Cited by 149 publications

(116 citation statements)

References 24 publications

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“…In CD, an iterative algorithm based on nonlinear Gauss-Seidel iterations is used to determine the contact forces and particle velocities simultaneously at all potential contacts. The CD method has been extensively employed for the simulation of granular materials in 2D and 3D [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72].…”

Section: Bonded Cell Modelmentioning

confidence: 99%

Bonded-cell model for particle fracture

et al. 2015

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Particle degradation and fracture play an important role in natural granular flows and in many applications of granular materials. We analyze the fracture properties of two-dimensional disklike particles modeled as aggregates of rigid cells bonded along their sides by a cohesive Mohr-Coulomb law and simulated by the contact dynamics method. We show that the compressive strength scales with tensile strength between cells but depends also on the friction coefficient and a parameter describing cell shape distribution. The statistical scatter of compressive strength is well described by the Weibull distribution function with a shape parameter varying from 6 to 10 depending on cell shape distribution. We show that this distribution may be understood in terms of percolating critical intercellular contacts. We propose a random-walk model of critical contacts that leads to particle size dependence of the compressive strength in good agreement with our simulation data.

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Section: Bonded Cell Modelmentioning

confidence: 99%

Bonded-cell model for particle fracture

et al. 2015

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“…The distributions are similar with nearly the same privileged direction aligned with the principal stress direction θ σ but with increasing anisotropy as a function of ξ. They all can be approximated by their truncated Fourier expansion [11,13,15]:…”

Section: A Granular Texturementioning

confidence: 99%

“…For example, it is found that in highly polydisperse systems the force chains are mainly captured by large particles so that the shear strength of a noncohesive granular material is practically independent of particle size distribution [12]. As another important example, a parametric study shows that when the particles interact by both sliding friction and high rolling resistance at their contacts, the nature of the weak network is affected by the formation of columnar structures which do not need to be propped by a particular class of weak contacts [13].…”

Section: Introductionmentioning

confidence: 99%

Force chains and contact network topology in sheared packings of elongated particles

2012

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By means of contact dynamic simulations, we investigate the contact network topology and force chains in two-dimensional packings of elongated particles modeled by rounded-cap rectangles. The morphology of large packings of elongated particles in quasistatic equilibrium is complex due to the combined effects of local nematic ordering of the particles and orientations of contacts between particles. We show that particle elongation affects force distributions and force/fabric anisotropy via various local structures allowed by steric exclusions and the requirement of force balance. As a result, the force distributions become increasingly broader as particles become more elongated. Interestingly, the weak force network transforms from a passive stabilizing agent with respect to strong force chains to an active force-transmitting network for the whole system. The strongest force chains are carried by side/side contacts oriented along the principal stress direction.

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“…In granular systems under loading, the force chains engaged along the entire system are a clear evidence of long-range interactions [18]. These chains connect the microscopic contact forces with the global resistance to external forces, as shear for example [19]. Thus, it is natural to associate the emergence of these force chains at mesoscopic scales with the departure from the classical Boltzmann-Gibbs (BG) statistics in these systems.…”

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confidence: 99%

Experimental Validation of a Nonextensive Scaling Law in Confined Granular Media

et al. 2015

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In this letter, we address the relationship between the statistical fluctuations of grain displacements for a full quasistatic plane shear experiment, and the corresponding anomalous diffusion exponent, α. We experimentally validate a particular case of the so-called Tsallis-Bukman scaling law, α = 2/(3 − q), where q is obtained by fitting the probability density function (PDF) of the measured fluctuations with a q-Gaussian distribution, and the diffusion exponent is measured independently during the experiment. Applying an original technique, we are able to evince a transition from an anomalous diffusion regime to a Brownian behavior as a function of the length of the strain-window used to calculate the displacements of grains in experiments. The outstanding conformity of fitting curves to a massive amount of experimental data shows a clear broadening of the fluctuation PDFs as the length of the strain-window decreases, and an increment in the value of the diffusion exponent -anomalous diffusion. Regardless of the size of the strain-window considered in the measurements, we show that the Tsallis-Bukman scaling law remains valid, which is the first experimental verification of this relationship for a classical system at different diffusion regimes. We also note that the spatial correlations show marked similarities to the turbulence in fluids, a promising indication that this type of analysis can be used to explore the origins of the macroscopic friction in confined granular materials. Turbulence is one of the most complex, but ubiquitous, phenomena observed in Nature and it is related with the underlying mechanisms responsible for the micro-macro upscale causing wide-ranging effects on classical systems, like macroscopic friction in granular solids or turbulent flow regime in fluids [1][2][3][4]. The presence of multiple scales in time and space is an additional defy to a comprehensive theoretical description, and a particular effort is made in the literature to perform experiments and simulations in order to validate the proposed theoretical descriptions, particularly Tsallis nonextensive (NE) statistical mechanics [5][6][7][8].A paradigmatic work relating anomalous diffusion and turbulent-like behavior in confined granular media was presented by Radjai and Roux [4], using numerical simulations, and confirmed qualitatively by experiments by Combe and collaborators [7,8]. Radjai and Roux coined a new expression to characterize the analogies between fluctuations of particle velocities in quasistatic granular flows and the velocity fields observed in turbulent fluid flow in high Reynolds number regime, the "granulence". Most of the evidences of the granulence are based in simulations using discrete element method (DEM) but, unfortunately, one can verify a lack of quantitative experimental verification in the last years, limiting the knowledge of the micromechanics of this system based almost exclusively on numerical evidences.In the present work, we aim exactly to fill this gap by contributing with the experiment...

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Shear strength and force transmission in granular media with rolling resistance

Cited by 149 publications

References 24 publications

Bonded-cell model for particle fracture

Bonded-cell model for particle fracture

Force chains and contact network topology in sheared packings of elongated particles

Experimental Validation of a Nonextensive Scaling Law in Confined Granular Media

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