Particle dynamics in two-dimensional point-loaded granular media composed of circular or pentagonal grains

Kozlowski, Ryan; Zheng, Hu; Daniels, Karen E.; Socolar, Joshua E. S.

doi:10.1051/epjconf/202124906010

Cited by 3 publications

(1 citation statement)

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“…In this section, we present observations of dynamics of grains and the stresses in the granular material. The motion of grains-translational and rotational-during slip events is captured from video tracking using the correlation template matching method described in [58,59] with white light images of the system. Detected disks and pentagons are shown in Figure 10.…”

Section: Dynamics and Stresses Of The Granular Materialsmentioning

confidence: 99%

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

et al. 2022

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

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Section: Dynamics and Stresses Of The Granular Materialsmentioning

confidence: 99%