Observation of a shape-dependent density maximum in random packings and glasses of colloidal silica ellipsoids

Sacanna, Stefano; Rossi, Laura; Wouterse, Alan; Philipse, Albert P.

doi:10.1088/0953-8984/19/37/376108

Cited by 71 publications

(99 citation statements)

References 25 publications

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“…For example, the presented method can be applied to a suspension of bidisperse colloids [39,40]. Another possible extension lies in the use of nonspherical hard colloids, for example, fluorescent rods [41,42], or polyhedral colloids [43] where exactly the same concepts can be applied. Constructing the available volume and its surface area then becomes more cumbersome, but in principle possible.…”

Section: Discussionmentioning

confidence: 99%

Direct Measurement of Thermodynamic Properties of Colloidal Hard Spheres

Dullens

Kegel

Aarts

2008

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Mesures directes des propriétés thermodynamiques de sphères dures colloïdales -Récemment, nous avons montré comment mesurer les propriétés de suspensions de sphères dures colloïdales par microscopie [Dullens et al. (2006) PNAS 103, 529]. Ici, nous présentons les détails expérimentaux complets sur la manière de capturer des images en trois dimensions d'une suspension de sphères dures colloïdales, couvrant une large gamme de densités, en utilisant la microscopie à laser confocal. De plus, nous approfondissons l'analyse des données et mesurons le volume disponible pour insérer une sphère additionnelle et l'aire de surface de ce volume. Ces propriétés géométriques sont liées aux grandeurs thermodynamiques clés par la géométrie statistique. Ceci nous permet de mesurer, d'une façon directe et non-intrusive, la pression, le potentiel chimique et la densité d'énergie libre d'une suspension de sphères dures ; ces mesures sont en bon accord avec les prédictions théoriques. Abstract -Direct Measurement of Thermodynamic Properties of Colloidal Hard SpheresRecently, we have shown how to measure thermodynamic properties of colloidal hard sphere suspensions by microscopy

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Section: Discussionmentioning

confidence: 99%

Direct Measurement of Thermodynamic Properties of Colloidal Hard Spheres

Dullens

Kegel

Aarts

2008

Oil & Gas Science and Technology - Rev. IFP

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“…These shape characteristics strongly affect the rheology and texture of granular materials. This has been recently evidenced by a number of numerical and experimental studies carried out using angular particles [1][2][3][4][5][6][7][8][9][10][11][12] and by a number of investigations that have focused on other important characteristics such as elongation [13][14][15][16][17][18][19][20] or non-convexity [21,22]. The existing research results suggest that the effect of shape parameters is often nonlinear and counterintuitive as in the case of the unmonotonic relation between the elongation of the particles and the packing fraction [13,14,18].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear effects of particle shape angularity in sheared granular media

2012

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We analyze the effects of particle shape angularity on the macroscopic shear behavior and texture of granular packings simulated by means of the contact dynamics method. The particles are regular polygons with an increasing number of sides ranging from 3 (triangles) to 60. The packings are analyzed in the steady shear state in terms of their shear strength, packing fraction, connectivity, and fabric and force anisotropies, as functions of the angularity. An interesting finding is that the shear strength increases with angularity up to a maximum value and saturates as the particles become more angular (below six sides). In contrast, the packing fraction declines towards a constant value, so that the packings of more angular particles are looser but have higher shear strength. We show that the increase of the shear strength at low angularity is due to an increase of both contact and force anisotropies, and the saturation of the shear strength for higher angularities is a consequence of a rapid fall-off of the contact and normal force anisotropies compensated by an increase of the tangential force anisotropy. This transition reflects clearly the rather special geometrical properties of these highly angular shapes, implying that the stability of the packing relies strongly on the side-side contacts and the mobilization of friction forces.

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“…Nevertheless, even if an increasing number of experimental and numerical studies have shown that the grain shape considerably affects the quasistatic behavior of granular materials [4,[6][7][8][9], systematic and quantitative investigations of shape or mixture of shape effects are still elusive. One of the difficulties is that the shape parameters mentioned above need to be defined conveniently in order to be able to generate particle shapes with continuouslyvariable shape parameters.…”

Section: Introductionmentioning

confidence: 99%

Systematic description of the effect of particle shape on the strength properties of granular media

et al. 2017

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Abstract. In this paper, we explore numerically the effect of particle shape on the mechanical behavior of sheared granular packings. In the framework of the Contact Dynamic (CD) Method, we model angular shape as irregular polyhedral particles, non-convex shape as regular aggregates of four overlapping spheres, elongated shape as rounded cap rectangles and platy shape as square-plates. Binary granular mixture consisting of disks and elongated particles are also considered. For each above situations, the number of face of polyhedral particles, the overlap of spheres, the aspect ratio of elongated and platy particles, are systematically varied from spheres to very angular, non-convex, elongated and platy shapes. The level of homogeneity of binary mixture varies from homogenous packing to fully segregated packings. Our numerical results suggest that the effects of shape parameters are nonlinear and counterintuitive. We show that the shear strength increases as shape deviate from spherical shape. But, for angular shapes it first increases up to a maximum value and then saturates to a constant value as the particles become more angular. For mixture of two shapes, the strength increases with respect of the increase of the proportion of elongated particles, but surprisingly it is independent with the level of homogeneity of the mixture. A detailed analysis of the contact network topology, evidence that various contact types contribute differently to stress transmission at the micro-scale.

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Observation of a shape-dependent density maximum in random packings and glasses of colloidal silica ellipsoids

Cited by 71 publications

References 25 publications

Direct Measurement of Thermodynamic Properties of Colloidal Hard Spheres

Direct Measurement of Thermodynamic Properties of Colloidal Hard Spheres

Nonlinear effects of particle shape angularity in sheared granular media

Systematic description of the effect of particle shape on the strength properties of granular media

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