Microdynamic analysis of solid flow in a shear cell

Wang, Xiaodong; Zhu, Haiping; Yu, Aibing

doi:10.1007/s10035-012-0311-x

Cited by 10 publications

(9 citation statements)

References 44 publications

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“…We use MercuryDPM [42,50], an open-source implementation of the discrete particle method, to simulate a shear cell with annular geometry and a split bottom plate, as shown in figure 1. Some of the earlier studies in similar rotating set-ups include [37,47,52]. The geometry of the system consists of an outer cylinder (outer radius R o =110 mm) rotating around a fixed inner cylinder (inner radius R i =14.7 mm) with a rotation frequency of Ω=0.01 revolutions per second.…”

Section: Split-bottom Ring Shear Cellmentioning

confidence: 99%

A general(ized) local rheology for wet granular materials

2017

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We study the rheology of dry and wet granular materials in the steady quasistatic regime using the discrete element method in a split-bottom ring shear cell with focus on the macroscopic friction. The aim of our study is to understand the local rheology of bulk flow at various positions in the shear band, where the system is in critical state. We develop a general(ized) rheology, in which the macroscopic friction is factorized into a product of four functions, on top of the classical ( ) m I rheology, each of which depends on exactly one dimensionless control parameter, quantifying the relative importance of different micro-mechanical machanisms. These four control parameters relate the time scales of shear rateġ t , particle stiffness t k , gravity t g and cohesion t c , respectively, with the governing time scale of confining pressure t p . Whileġ t is large and thus of little importance for most of the slow flow data studied, it increases the friction in critical state, where the shear rate is high and decreases friction by relaxation (creep) where the shear rate is low. t g and t k are comparable to t p in the bulk, but become more or less dominant relative to t p at the extremes of low pressure at the free surface and high pressure deep inside the bulk, respectively. The effect of wet cohesion on the flow rheology is quantified by t c decreasing with increasing cohesion. Furthermore, the proposed rheological model predicts well the shear thinning behavior both in the bulk and near the free surface; shear thinning rate becomes less near the free surface with increasing cohesion.

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Section: Split-bottom Ring Shear Cellmentioning

confidence: 99%

A general(ized) local rheology for wet granular materials

2017

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“…Earlier studies used similar rotating set-ups, including [7,8]. The geometry of the system consists of an outer cylinder (radius R o = 110 mm) rotating around a fixed inner cylinder (radius R i = 14.7 mm) with a rotation frequency of Ω = 2π f and f = 0.01 revolutions per second.…”

Section: Geometrymentioning

confidence: 99%

Effect of cohesion on local compaction and granulation of sheared soft granular materials

2017

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Abstract. This paper results from an ongoing investigation of the effect of cohesion on the compaction of sheared soft wet granular materials. We compare dry non-cohesive and wet moderately-to-strongly cohesive soft almost frictionless granular materials and report the effect of cohesion between the grains on the local volume fraction. We study this in a three dimensional, unconfined, slowly sheared split-bottom ring shear cell, where materials while sheared are subject to compression under the confining weight of the material above. Our results show that inter-particle cohesion has a considerable impact on the compaction of soft materials. Cohesion causes additional stresses, due to capillary forces between particles, leading to an increase in volume fraction due to higher compaction. This effect is not visible in a system of infinitely stiff particles. In addition, acting oppositely, we observe a general decrease in volume fraction due to increased cohesion for frictional particle, which we attribute to the role of contact friction that enhances dilation.

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“…Split-Bottom Ring Shear Cell: The set-up used for simulations consists of a shear cell with annular geometry and a split in the bottom plate, as shown in figure 1. Some of the earlier studies in similar rotating set-up include [24,25,26]. The geometry of the system consists of an outer cylinder (radius R o = 110 mm) rotating around a fixed inner cylinder (radius R i = 14.7 mm) with a rotation frequency of f rot = 0.01 s −1 .…”

Section: Geometrymentioning

confidence: 99%

“…1. Some of the earlier studies in similar rotating set-up include [24][25][26]. The geometry of the system consists of an outer cylinder (radius R o = 110 mm) rotating around a fixed inner cylinder (radius R i = 14.7 mm) with a rotation frequency of f rot = 0.01s −1 .…”

Section: Geometrymentioning

confidence: 99%

Micro–macro transition and simplified contact models for wet granular materials

et al. 2015

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Wet granular materials in a quasistatic steadystate shear flow have been studied with discrete particle simulations. Macroscopic quantities, consistent with the conservation laws of continuum theory, are obtained by time averaging and spatial coarse graining. Initial studies involve understanding the effect of liquid content and liquid properties like the surface tension on the macroscopic quantities. Two parameters of the liquid bridge contact model have been identified as the constitutive parameters that influence the macroscopic rheology (i) the rupture distance of the liquid bridge model, which is proportional to the liquid content, and (ii) the maximum adhesive force, as controlled by the surface tension of the liquid. Subsequently, a correlation is developed between these microparameters and the steady-state cohesion in the limit of zero confining pressure. Furthermore, as second result, the macroscopic torque measured at the walls, which is an experimentally accessible parameter, is predicted from our simulation results with the same dependence on the microparameters. Finally, the steady-state cohesion of a realistic non-linear liquid bridge contact model scales well with the steady-state cohesion for a simpler linearized irreversible contact model with the same maximum adhesive force and equal energy dissipated per contact. B Sudeshna Roy

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Microdynamic analysis of solid flow in a shear cell

Cited by 10 publications

References 44 publications

A general(ized) local rheology for wet granular materials

A general(ized) local rheology for wet granular materials

Effect of cohesion on local compaction and granulation of sheared soft granular materials

Micro–macro transition and simplified contact models for wet granular materials

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