Effect of vibration condition and inter-particle frictions on the packing of uniform spheres

An, Xizhong; Yang, Runyu; Zou, Ruiping; Yu, Aibing

doi:10.1016/j.powtec.2008.04.001

Cited by 90 publications

(29 citation statements)

References 32 publications

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“…[14][15][16][17][18][19][20] While compared with mostly studied compaction and sintering processes, this step is less concerned. Based on previous studies on the packing of coarse particles or fine powders, An et al have identified that by using external energy generated by mechanical vibration or compression, the transition from the so called random loose packing (RLP) to random close packing (RCP) can be reproduced numerically and physically, [21][22][23][24][25][26] where the obtained RCP structure with densest random packing density, small pore size, and uniform pore size distribution can provide the researchers with effective starting point, useful ideas, and references for high-quality PM production. However, to date, corresponding studies which considering the effects of initial packing structures on the packing densification during powder die compaction is limited.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Modeling on the Compaction of Copper Powder Under Different Conditions

Zhang²,

Zhang

et al. 2015

Metall Mater Trans A

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Single-action die compaction of copper powders with initial loose natural packing and vibrated random dense packing structures was carried out numerically by finite element method and physically for validation. Furthermore, the compaction under various cyclic loadings was modeled to identify its effects on the compact properties. The results were analyzed and compared between compacts formed at different initial packing structures and different forming conditions, which indicate that at the same pressure, single-action die compaction on the dense uniform initial packing can produce compacts with high relative density, uniform density and stress distributions, which implies the necessity to improve initial packing density and uniformity in forming high performance compacts. Meanwhile, by using cyclic loading on such dense initial packing structures, compacts with higher packing density and more uniform density and stress distributions can be created. The numerical and physical results are comparable and in good agreement with the proposed double logarithmic equation.

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Section: Introductionmentioning

confidence: 99%

Finite Element Modeling on the Compaction of Copper Powder Under Different Conditions

Zhang²,

Zhang

et al. 2015

Metall Mater Trans A

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“…The second class of methods, dynamic algorithms, consists in imitating experiments by simulating spheres submitted to forces and undergoing contacts. For example, in [17,29], spheres are falling due to gravity in a cube with periodic boundary conditions and in [1] vibrations of the bottom are added. In [29], the authors use Molecular Dynamics to simulate 20, 000 rigid spheres with partially elastic contacts while in [17] the 10, 000 spheres are supposed to be deformable.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Numerical Investigation of Random Packing for Spherical and Nonconvex Particles

2009

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Abstract. We simulate the sedimentation in a parallelepipedic container of spheres and nonconvex particles constituted by two overlapping spheres. We use the self-written code SCoPI. Thanks to an efficient handling of contacts between particles, it allowed us to consider up to 100, 000 spheres and 10, 000 nonconvex particles. The packing fraction (in bulk and close to a wall) as well as the mean value and the distribution of contacts of the final packings are reported. The results obtained for the classical case of spherical particles (packing fraction: 63.7%, mean number of contacts: 6) are in agreement with previous studies and validate the algorithm. The packing fraction for nonconvex particles increases and then decreases with respect to the aspect ratio, which is similar to the ellipsoid (convex) case. The number of contacts is different from the number of neighbours, which is of course never the case for spherical particles (convex particles). The number of contacts is discontinuous when slightly increasing the aspect ratio from the spherical case: it is equal to 6 in the spherical case and to 10 in the nonconvex case. These values correspond to the isocounting values, i.e. the number of contacts is twice the number of degrees of freedom. This contrasts with the ellipsoid case, where it sharply but continuously increases. Concerning the number of neighbours, it continuously increases for small aspect ratio (which is similar to the convex particle case), but decreases for higher aspect ratio.Résumé. Nous simulons la sédimentation dans un récipient parallélépipédique de sphères et de particules non convexes formées de deux sphères se chevauchant. Afin de réaliser ces simulations, de nouvelles fonctionnalités ontété ajoutées au logiciel SCoPI initialement développé par A. Lefebvre-Lepot. Grâcè a une prise en compte efficace des contacts, il nous a permis de considérer jusqu'à 100, 000 sphères et 10, 000 particules non convexes. La compacité (en volume et près d'une paroi), ainsi que la valeur moyenne et la distribution du nombre de contacts des configurations finales sont décrites. Les résultats obtenus dans le cas classique de particules sphériques (compacité de 63.7%, nombre moyen de contacts de 6) sont en accord avec de précédentesétudes et permettent de valider l'algorithme. La compacité pour les particules non convexes augmente puis diminue en fonction du rapport d'aspect, ce qui est similaire au cas (convexe) des ellipsoïdes. Le nombre de contacts est différent du nombre de voisins, ce qui bien entendu n'est jamais le cas pour des sphères (particules convexes). Le nombre de contacts est discontinu lorsque l'on augmente légèrement le rapport d'aspectà partir d'une sphère: il estégal a 6 dans le cas sphérique età 10 dans le cas non convexe. Ces valeurs correspondent aux valeurs isostatiques, c'està dire que le nombre de contacts estégal au double du nombre de degrés de liberté. Ce résultat diffère du cas des ellipsoïdes où il augmente fortement mais continûment. Quant au nombre de voisins, il augmente con...

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“…Plots of the number fraction distributions of light particles in the vertical direction for the four types of binary mixtures (Figure 3e) confirm quantitatively that the granular beds are composed largely of random mixtures. In recent experimental 25,26 and computational studies, 27,28 it has been demonstrated that granular beds subjected to vibrations at specific amplitudes and frequencies may undergo a process referred to as densification rather than fluidization. The solid particles assemble into crystalline structures, which hinder relative motions within the granular bed.…”

Section: Resultsmentioning

confidence: 99%

Density segregation in vibrated granular beds with bumpy surfaces

Lim

2010

AIChE Journal

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Segregation of granular materials by virtue of density or size is a commonly encountered phenomenon in nature. Despite its widespread interest among many researchers in recent years, a complete and unified understanding of granular segregation remains elusive to date. Using molecular dynamics simulations, we report a novel technique of inducing density segregation in a binary mixture of granular materials subjected to vibrations by the use of a bumpy vibrating base. Density segregation in the vertical directions may be induced by oscillating the bumpy base composed of discrete solid particles vertically or horizontally. In both cases, lighter particles tended to rise to the top of the granular bed and form a layer above the heavier particles. We suggest that differences in granular temperature profiles arising from the two different modes of vibrations may play an important role in determining the extent of density segregation occurring in binary granular mixtures. © 2010 American Institute of Chemical Engineers AIChE J, 2010

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Effect of vibration condition and inter-particle frictions on the packing of uniform spheres

Cited by 90 publications

References 32 publications

Finite Element Modeling on the Compaction of Copper Powder Under Different Conditions

Finite Element Modeling on the Compaction of Copper Powder Under Different Conditions

Dynamic Numerical Investigation of Random Packing for Spherical and Nonconvex Particles

Density segregation in vibrated granular beds with bumpy surfaces

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