Packings of 3D stars: Stability and structure

Abstract

We describe a series of experiments involving the creation of cylindrical packings of star-shaped particles, and an exploration of the stability of these packings. The stars cover a broad range of arm sizes and frictional properties. We carried out three different kinds of experiments, all of which involve columns that are prepared by raining star particles one-by-one into hollow cylinders. As an additional part of the protocol, we sometimes vibrated the column before removing the confining cylinder. We rate stability in terms of r, the ratio of the mass of particles that fall off a pile when it collapsed, to the total particle mass. The first experiment involved the intrinsic stability of the pile when the confining cylinder was removed. The second kind of experiment involved adding a uniform load to the top of the column, and then determining the collapse properties. A third experiment involved testing stability to tipping of the piles. We find a stability diagram relating the pile height, h, vs. pile diameter, delta, where the stable and unstable regimes are separated by a boundary that is roughly a power-law in h vs. delta with an exponent that is less than one. Increasing friction and vibration both tend to stabilize piles, while increasing particle size can destabilize the system under certain conditions.

9 Pages, 9 figures. Submitted to Granular Matter

References in corpus (7)

• Particle Shape Effects on the Stress Response of Granular Packings
• Optimal Packings of Superballs
• Dense Regular Packings of Irregular Non-Convex Particles
• Jamming of 3D Prolate Granular Materials
• Column collapse of granular rods
• Strain-stiffening in random packings of entangled granular chains
• Athermal jamming of soft frictionless Platonic solids

Cited by in corpus (7)

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• Self-organized magnetic particles to tune the mechanical behaviour of a granular system
• The Link Between Packing Morphology and the Distribution of Contact Forces and Stresses in Packings of Highly Non-Convex Particles
• Micromechanical description of the compaction of soft pentagon assemblies
• Jamming transition in non-spherical particle systems: pentagons vs. disks
• The effects of interparticle cohesion on the collapse of granular columns
• Stagnant Zone Formation in a 2D Bed of Circular and Elongated Grains under Penetration