Yielding, rigidity, and tensile stress in sheared columns of hexapod granules
Abstract
Granular packings of non-convex or elongated particles can form free-standing
structures like walls or arches. For some particle shapes, such as staples, the
rigidity arises from interlocking of pairs of particles, but the origins of
rigidity for non-interlocking particles remains unclear. We report on
experiments and numerical simulations of sheared columns of ``hexapods,''
particles consisting of three mutually orthogonal sphero-cylinders whose
centers coincide. We vary the length-to-diameter aspect ratio, $\alpha$, of the
sphero-cylinders and subject the packings to quasistatic direct shear. For
small $\alpha$, we observe a finite yield stress. For large $\alpha$, however,
the column becomes rigid when sheared, supporting stresses that increase
sharply with increasing strain. Analysis of X-ray micro-computed tomography
(Micro-CT) data collected during the shear reveals that the stiffening is
associated with a tilted, oblate cluster of hexapods near the nominal shear
plane in which particle deformation and average contact number both increase.
Simulation results show that the particles are collectively under tension along
one direction even though they do not interlock pairwise. These tensions comes
from contact forces carrying large torques, and they are perpendicular to the
compressive stresses in the packing. They counteract the tendency to dilate,
thus stabilize the particle cluster.
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https://hdl.handle.net/10161/21148Published Version (Please cite this version)
10.1103/physreve.101.062903Publication Info
Zhao, Yuchen; Barés, Jonathan; & Socolar, Joshua ES (n.d.). Yielding, rigidity, and tensile stress in sheared columns of hexapod granules. Physical Review E, 101(6). pp. 062903. 10.1103/physreve.101.062903. Retrieved from https://hdl.handle.net/10161/21148.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Joshua Socolar
Professor of Physics
Prof. Socolar is interested in collective behavior in condensed matter and dynamical
systems. His current research interests include:
Limit-periodic structures, quasicrystals, packing problems, and tiling theory;
Self-assembly and phases of designed colloidal particles;
Organization and dynamics of complex networks;
Topological elasticity of mechanical lattices.
Yuchen Zhao
Student
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