3D mapping of deformation in an unconsolidated sand: A micro mechanical study

Saadatfar, Mohammad; Nicolas, François; Arad, Alon; Madadi, Mahyar; Cruikshank, Ron; Alizadeh, Mehdi; Sheppard, Adrian; Kingston, Andrew; Limay, Ajay; Senden, Tim J.; Knackstedt, Mark

doi:10.1190/segam2012-1263.1

Cited by 9 publications

(8 citation statements)

References 18 publications

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“…Recent advances point out the importance of the network of enduring contacts for determining nonlocal constitutive laws of dense granular flows [36]. In monodisperse granular materials, polytetrahedral clusters might partially map onto this contact network and could enlighten the spatial organization of the mechanical backbone [37]. Interestingly, a transition in the mechanical coordination number of packings has recently been reported to occur for 2 ½0:64; 0:68 [12].…”

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confidence: 99%

Geometrical Frustration in Amorphous and Partially Crystallized Packings of Spheres

et al. 2013

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We study the persistence of a geometrically frustrated local order inside partially crystallized packings of equal-sized spheres. Measurements by x-ray tomography reveal previously unseen grain scale rearrangements occurring inside large three-dimensional packings as they crystallize. Three successive structural transitions are detected by a statistical description of the local volume fluctuations. These compaction regimes are related to the disappearance of densely packed tetrahedral patterns of beads. Amorphous packings of monodisperse spheres are saturated with these tetrahedral clusters at Bernal's limiting density (φ≈64%). But, no periodic lattice can be built upon these patterns; they are geometrically frustrated and are thus condemned to vanish while the crystallization occurs. Remarkably, crystallization-induced grain rearrangements can be interpreted in terms of the evolution of key topological features of these aggregates.

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confidence: 99%

Geometrical Frustration in Amorphous and Partially Crystallized Packings of Spheres

et al. 2013

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“…Our findings have also practical applications in domains such as pore description in soil-and geo-sciences, which are crucial for understanding natural systems mechanical stability, vibration induced compaction and flow permeability [23][24][25].…”

Section: Discussionmentioning

confidence: 78%

Granular compaction and the topology of pore deformation

et al. 2017

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The mechanism of crystallisation in highly dissipative materials such as foams or granular materials is still widely unknown. In macroscopic granular materials high levels of energy need to be injected to overcome the natural propensity of these dissipative materials to form amorphous structures [1, 2]. The transition from disordered to ordered packings in such systems triggers a wide range of geometrical, topological and mechanical changes at multi length scales [3]. Formation of cavities and patterns by aggregates of grains and their evolution during this transition requires a complete topological description of the system. Here, crystallisation of three-dimensional packings of frictional spheres is studied at the grain scale with x-ray tomography. Using a novel and powerful topological tool, Persistent Homology, we describe the complete formation process of perfect tetrahedral and octahedral patterns: the two building blocks of FCC and HCP crystalline arrangements. Additionally we present possible and allowable deformations of these components that accurately reproduce the main topological features of the system. These results give new insights into the crystallisation of these highly dissipative materials.

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“…Our findings have also practical applications in domains such as pore description in soil and geo-sciences, which are crucial for understanding natural systems mechanical stability, vibration-induced compaction and flow permeability485556.…”

Section: Discussionmentioning

confidence: 79%

Pore configuration landscape of granular crystallization

et al. 2017

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Uncovering grain-scale mechanisms that underlie the disorder–order transition in assemblies of dissipative, athermal particles is a fundamental problem with technological relevance. To date, the study of granular crystallization has mainly focussed on the symmetry of crystalline patterns while their emergence and growth from irregular clusters of grains remains largely unexplored. Here crystallization of three-dimensional packings of frictional spheres is studied at the grain-scale using X-ray tomography and persistent homology. The latter produces a map of the topological configurations of grains within static partially crystallized packings. Using numerical simulations, we show that similar maps are measured dynamically during the melting of a perfect crystal. This map encodes new information on the formation process of tetrahedral and octahedral pores, the building blocks of perfect crystals. Four key formation mechanisms of these pores reproduce the main changes of the map during crystallization and provide continuous deformation pathways representative of the crystallization dynamics.

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3D mapping of deformation in an unconsolidated sand: A micro mechanical study

Cited by 9 publications

References 18 publications

Geometrical Frustration in Amorphous and Partially Crystallized Packings of Spheres

Geometrical Frustration in Amorphous and Partially Crystallized Packings of Spheres

Granular compaction and the topology of pore deformation

Pore configuration landscape of granular crystallization

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