Contact force measurements and local anisotropy in ellipses and disks
arXiv:2105.07607
Abstract
Experimental measurements of contact forces are limited to spheres and disks in three and two dimensions, making the evaluation of the shape effect and universality of force distributions and the comparison between experiments and theories extremely difficult. Here we present precise measurements of vector contact forces in photoelastic ellipses and disks subject to isotropic compression and pure shear. We find the local, instead of the global, stress ratio, control the width of the force distributions for forces larger than the mean, regardless of the particle shape and preparation protocols. By taking advantage of the anisotropic particle shape, we can determine the anisotropic growth of contacts in ellipses subject to isotropic compression, revealing the role of non-affine particle motions in homogenizing force distributions. Our results uncover the role of local anisotropy in the statistical framework of granular materials and open a new regime of exploring the role of particle shape on the mechanical and dynamical properties of granular materials in depth.
arXiv comment18 pages, 4 figures
References in corpus (13)
- Force Distribution in a Granular Medium
- Jamming transition in emulsions and granular materials
- Force distributions near the jamming and glass transitions
- Force chains and contact network topology in packings of elongated particles
- Statistics of the contact network in frictional and frictionless granular packings
- A statistical mechanics framework for static granular matter
- Spanning the Scales of Granular Materials: Microscopic Force Imaging
- The tail of the contact force distribution in static granular materials
- Connecting shear localization with the long-range correlated polarized stress fields in granular materials
- The Link Between Packing Morphology and the Distribution of Contact Forces and Stresses in Packings of Highly Non-Convex Particles
- Master equation for the probability distribution functions of forces in soft particle packings
- Force balance in canonical ensembles of static granular packings
- Evolution of the force distributions in jammed packings of soft particles