Rolling Resistance at Contacts in Simulation of Shear Band Development by DEM

Iwashita, K.; Oda, Masanobu

doi:10.1061/(asce)0733-9399(1998)124:3(285)

Cited by 733 publications

(350 citation statements)

References 23 publications

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“…where i m is the mass of particle i; i x is the position of its centroid; g is the gravitational acceleration; nc f and tc f are the normal and tangential particle-particle contact forces exerted by the neighbouring particles on particle i, which are calculated using the linearspring and rolling resistance model as detailed by Iwashita [36], Jiang et al [37] and…”

Section: Equations Governing Particle Motionmentioning

confidence: 99%

Investigation of granular batch sedimentation via DEM–CFD coupling

2014

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process, the excess pore water pressure initially increases rapidly to a peak value, and then dissipates gradually to zero. Meanwhile, the compressibility of the sediments decreases slowly as a soil layer builds up at the bottom. Consolidation of the deposited layer is caused by the self-weight of grains, while the compressibility of the sample decreases progressively.Keywords: granular batch sedimentation, DEM-CFD coupling, segregation, pore water pressure, effective stress, compressibility IntroductionThe sedimentation and consolidation processes of granular materials are common in both terrestrial and submerged environments. In the natural environment, granular materials often settle continuously towards the seabed, lake or river floor to form a loose sediment layer. As the skeleton of the sediment layer is extremely compressible, it undergoes relatively large strain under additional loads. Sedimentation processes are very important for solid-liquid 1 2

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Section: Equations Governing Particle Motionmentioning

confidence: 99%

Investigation of granular batch sedimentation via DEM–CFD coupling

2014

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“…Similarly to the observations for the torsional loading, although some discrepancy can be observed for an MR of 0·045, for MR values of 0·014 and 0·023 a good agreement between the curves is shown. Here, the rolling resistance is derived from the actual rotational moment between two contacting bodies, which differs from the artificial rolling resistance used in previous studies to account for the effect of grain shape (Iwashita & Oda, 1998;Jiang et al, 2005).…”

Section: Rotational Loadingmentioning

confidence: 99%

A micro finite-element model for soil behaviour: numerical validation

Nadimi

Fonseca

2018

Géotechnique

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This is the published version of the paper.This version of the publication may differ from the final published version. A micro finite-element (μFE) model capable of handling arbitrary shapes and deformable grains has been developed by the authors. The basis of this μFE model is to use a virtualised soil fabric obtained from micro computed tomography (μCT) of real sand to simulate grain-to-grain interaction in a framework of combined discrete-finite-element method. By incorporating grain deformation into the model, the contact response emerges from the interaction of contacting bodies and each irregular contact area will produce a unique response. A detailed numerical description of grain morphology and contact topology of a natural sand and the subsequent simulation are presented in the original paper. The present study focuses on the numerical validation of the constitutive contact behaviour against existent theories, for a single sphere and an assembly of spheres. The ability of the model to simulate elastic-plastic behaviour making use of the deformability of the grains is demonstrated. The unloading-reloading behaviour associated with the geometrical arrangement of the grains for a granular assembly under triaxial compression is examined in terms of energy dissipation quantities. Permanent repository link:

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“…Table 1 provides a summary of the simulation and material parameters used. The stiffness coefficients -rolling resistance and contact moment -are selected according to the assumption that subject to equilibrium conditions, contact moments due to rolling resistance are comparable to contact moments due to tangential forces (Iwashita and Oda, 1998 coefficients for normal and tangential forces are given by…”

Section: Discrete Element Simulationsmentioning

confidence: 99%

Force chain and contact cycle evolution in a dense granular material under shallow penetration

Tordesillas

Steer

Walker

2014

Nonlin. Processes Geophys.

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Abstract. The mechanical response of a dense granular material submitted to indentation by a rigid flat punch is examined. The resultant deformation is viewed as a process of self-organisation. Four aspects of the mechanical response (i.e. indentation resistance, failure, Reynolds' dilatancy, the undeforming "dead zone") are explored with respect to the linear and cyclic structural building blocks of granular media self-organisation: force chains and contact network cycles. Formation and breaking of 3-cycle contacts preferentially occur around and close to the punch uncovering a "dilation zone". This zone encapsulates (i) most of the indentation resistance and is populated by force chains consisting of six or more particles, (ii) all buckling force chains, and (iii) a central, near-triangular, undeforming cluster of grains beneath the punch face. Force chain buckling is confined to the zone's outer regions, beneath the corners and to the sides of the punch where surface material heave forms. Grain rearrangements here involve the creation of 6-, 7-, and 8-cycles -in contrast with Reynolds' postulated cubic packing rearrangements (i.e. 3-cycles opening up to form 4-cycles). In between these intensely dilatant regions lies a compacted triangular grain cluster which moves in near-rigid body with the punch when jammed, but this dead zone unjams and deforms in the failure regimes when adjacent force chains buckle. The long force chains preferentially percolate from the punch face, through the dead zone, fanning downwards and outwards into the material.

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Rolling Resistance at Contacts in Simulation of Shear Band Development by DEM

Cited by 733 publications

References 23 publications

Investigation of granular batch sedimentation via DEM–CFD coupling

Investigation of granular batch sedimentation via DEM–CFD coupling

A micro finite-element model for soil behaviour: numerical validation

Force chain and contact cycle evolution in a dense granular material under shallow penetration

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