Stick-Slip Dynamics in a Granular Material With Varying Grain Angularity

Experiments, simulations, and theoretical treatments of granular materials typically feature circular or elliptical grains. However, grains found in natural systems often have flat faces that introduce local rotational constraints; these constraints been shown to affect, for example, the jamming transition, discontinuous shear thickening, ordered states colloids thermalized In this work, we experimentally investigate effects grain angularity on stick-slip dynamics. A weighted slider is pulled by a spring over gravity-packed bed composed polygonal with varying angularity. We find packings triangular square higher strengths than pentagons, hexagons, heptagons, disks. Additionally, as number sides increases, sticking periods, during which remains motionless while force it become shorter average, material yielding at smaller applied stresses. Lastly, dilation medium periods tends be larger angularity, part because presence stilt-like columnar structures prop up. report measurements pulling slider, particle dynamics slip events, properties force-bearing contact networks identified via photoelasticity. Our findings indicate high (pentagons, squares, triangles) leads differences grain-scale flow macroscopic bulk materials. experiments also continuous change decreasing limit approached.