A study on tangential force laws applicable to the discrete element method (DEM) for materials with viscoelastic or plastic behavior

Kruggel‐Emden, Harald; Wirtz, S.; Scherer, Viktor

doi:10.1016/j.ces.2007.11.025

Cited by 200 publications

(91 citation statements)

References 47 publications

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“…We used the value they give μ gw = 0.596 for the grain and wall contacts in our simulations, together with all their normal and tangential restitution measurements (see Table I). These restitution coefficients could be refined for binary collisions using precise velocity-dependent measures fitted by more complicated models [37], but this would not necessarily give better global results given the multiple-and long-lasting contacts [37], so we stick to the experimental values given by Refs. [2,34].…”

Section: Simulation Methodsmentioning

confidence: 99%

“…, with some direction within the tangential plane) of the impact velocity, k t and γ t a model spring stiffness and a model viscosity, and s is a bounded version |s| |F t |/k t of the sliding displacement τ τ 0 v t dτ in the tangential plane since contact time τ 0 [37]. Coulomb friction |F t | μ|F n | is enforced on the tangential component, with a model coefficient μ.…”

Section: Simulation Methodsmentioning

confidence: 99%

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Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

2013

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Granular flows down inclined channels with smooth boundaries are common in nature and industry. Nevertheless, flat boundaries have been much less investigated than bumpy ones, which are used by most experimental and numerical studies to avoid sliding effects. Using numerical simulations of each grain and of the side walls we recover quantitatively experimental results. At larger angles we predict a rich behavior, including granular convection and inverted density profiles suggesting a Rayleigh-Bénard type of instability. In many aspects flows on a flat base can be seen as flows over an effective bumpy base made of the basal rolling layer, giving Bagnold-type profiles in the overburden. We have tested a simple viscoplastic rheological model [Nature (London) 441, 727 (2006)] in average form. The transition between the unidirectional and the convective flows is then clearly apparent as a discontinuity in the constitutive relation.

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Section: Simulation Methodsmentioning

confidence: 99%

Section: Simulation Methodsmentioning

confidence: 99%

Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

2013

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“…In this approach, normal and tangential contact forces are calculated using various laws [7][8][9], which are based on the local body deformation at the point of contact. In the contact-normal direction, this local body deformation is defined as the penetration (overlap) of the two quasi-rigid bodies.…”

Section: The Discrete Element Methods (Dem)mentioning

confidence: 99%

On the Importance of Displacement History in Soft-Body Contact Models

Fleischmann

Serban

Negrut

et al. 2015

Journal of Computational and Nonlinear Dynamics

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Two approaches are commonly used for handling frictional contact within the framework of the discrete element method (DEM). One relies on the complementarity method (CM) to enforce a nonpenetration condition and the Coulomb dry-friction model at the interface between two bodies in mutual contact. The second approach, called the penalty method (PM), invokes an elasticity argument to produce a frictional contact force that factors in the local deformation and relative motion of the bodies in contact. We give a brief presentation of a DEM-PM contact model that includes multi-time-step tangential contact displacement history. We show that its implementation in an open-source simulation capability called Chrono is capable of accurately reproducing results from physical tests typical of the field of geomechanics, i.e., direct shear tests on a monodisperse material. Keeping track of the tangential contact displacement history emerges as a key element of the model. We show that identical simulations using contact models that include either no tangential contact displacement history or only single-time-step tangential contact displacement history are unable to accurately model the direct shear test.

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“…There is a variety of models to describe the contact forces in DEM simulations, which are suitable for different particle geometry and material behavior. [23][24][25][26] In the present paper, we assume viscoelastic interaction in the normal direction 27 and apply a modified Cundall-Strack model 28 for the tangential direction. 29 The corresponding forces read…”

Section: Numerical Experimentsmentioning

confidence: 99%

Helical inner-wall texture prevents jamming in granular pipe flows

2015

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Granular pipe flows are characterized by intermittent behavior and large, potentially destructive solid fraction variations in the transport direction. By means of particle-based numerical simulations of gravity-driven flows in vertical pipes, we show that it is possible to obtain steady material transport by adding a helical texture to the inner-wall of the pipe. The helical texture leads to a more homogeneous mass flux along the pipe, prevents the emergence of large density waves and substantially reduces the probability of plug formation thus avoiding jamming of the particulate flow. We show that the granular mass flux Q through a pipe of diameter D with a helical texture of wavelength l follows the equation

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A study on tangential force laws applicable to the discrete element method (DEM) for materials with viscoelastic or plastic behavior

Cited by 200 publications

References 47 publications

Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

Shallow granular flows down flat frictional channels: Steady flows and longitudinal vortices

On the Importance of Displacement History in Soft-Body Contact Models

Helical inner-wall texture prevents jamming in granular pipe flows

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