The effect of contact torques on porosity of cohesive powders

Bartels, Guido; Unger, Tamás; Kadau, Dirk; Wolf, Dietrich E.; Kertész, János

doi:10.1007/s10035-004-0184-8

Cited by 34 publications

(30 citation statements)

References 23 publications

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“…Rolling-and torsion-resistance [2,16,17,44,62,78] can play an important role in particle systems, since they also lead to torques, typically reducing the particles' freedom to rotate. This can be used to mimick the effects of surface roughness and non-spherical shapes to some extent [57][58][59], but naturally, non-spherical particles require more advanced algorithms [31,52,89]-not discussed further in this study.…”

Section: Frictional Contact Modelsmentioning

confidence: 99%

Cohesive, frictional powders: contact models for tension

Luding¹

2008

Granular Matter

514

431

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The contacts between cohesive, frictional particles with sizes in the range 0.1-10 µm are the subject of this study. Discrete element model (DEM) simulations rely on realistic contact force models-however, too much details make both implementation and interpretation prohibitively difficult. A rather simple, objective contact model is presented, involving the physical properties of elastic-plastic repulsion, dissipation, adhesion, friction as well as rollingand torsion-resistance. This contact model allows to model bulk properties like friction, cohesion and yield-surfaces. Very loose packings and even fractal agglomerates have been reported in earlier work. The same model also allows for pressure-sintering and tensile strength tests as presented in this study.

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Section: Frictional Contact Modelsmentioning

confidence: 99%

Cohesive, frictional powders: contact models for tension

Luding¹

2008

Granular Matter

514

431

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“…The present communication investigates those phenomena by discrete element simulations in quasistatic conditions. Such a situation, with loose systems, has hardly been addressed by numerical means, as the recent literature rather explored dynamic compaction [4,5], gravity deposition [6], steady flows [7], or denser materials [8,9]. We introduce a simple model material and report on its consolidation properties, in relation to its microstructure, thus presenting a brief account of studies published in two recent papers [10,11], to which a section with new results on the resistance to tension is added.…”

Section: Introductionmentioning

confidence: 99%

Discrete simulation of model, loose cohesive powders: plastic consolidation, fractal microstructure and tensile strength

Gilabert¹,

Roux²,

Castellanos³

2009

AIP Conference Proceedings

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Abstract. Isotropic packings of cohesive disks in 2D are studied by discrete, stress-controlled numerical simulations. Depending on the assembling process and on whether contacts possess rolling resistance (RR), configurations form under low pressure P with varying solid fraction Φ and fractal dimension d F describing small scale correlations below some blob size ξ . The gradual collapse observed under growing P is described as a linear relation between ln P and 1/Φ within some range, once the influence of initial conditions has faded out, and until a maximum density is approached. This corresponds to a decrease of ξ that is compatible with the fractal blob model. The isotropic tensile strength is always considerably smaller than the naive Rumpf estimate, and grows with consolidation. Coordination numbers in systems with small RR change little while density increases by large amounts in consolidation.

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“…Typically the values of the density can depend on these parameters as shown in Ref. [37] whereas the qualitative behavior does not change. Figure 1 shows the final structures obtained for different values of granular Bond number ranging from 0 to 10 6 .…”

Section: Density Profiles When Gravity Acts During Depositionmentioning

confidence: 95%

“…Here we consider the bonding between two particles in terms of a cohesion model with a constant attractive force F c acting within a finite range d c , so that for the opening of a contact a finite energy barrier F c d c must be overcome. In addition, we implement Coulomb and rolling friction between two particles in contact, so that large pores can be stable [32,[36][37][38][39].…”

Section: Description Of Simulation Modelmentioning

confidence: 99%

Density profiles of loose and collapsed cohesive granular structures generated by ballistic deposition

Kadau

Herrmann

2011

Phys. Rev. E

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Loose granular structures stabilized against gravity by an effective cohesive force are investigated on a microscopic basis using contact dynamics. We study the influence of the granular Bond number on the density profiles and the generation process of packings, generated by ballistic deposition under gravity. The internal compaction occurs discontinuously in small avalanches and we study their size distribution. We also develop a model explaining the final density profiles based on insight about the collapse of a packing under changes of the Bond number.

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The effect of contact torques on porosity of cohesive powders

Cited by 34 publications

References 23 publications

Cohesive, frictional powders: contact models for tension

Cohesive, frictional powders: contact models for tension

Discrete simulation of model, loose cohesive powders: plastic consolidation, fractal microstructure and tensile strength

Density profiles of loose and collapsed cohesive granular structures generated by ballistic deposition

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