System Size Dependence in Shear Jamming of 2D Frictional Grains*

Shear jamming (SJ) occurs for frictional granular materials with packing fractions (Φ) in a finite range below the isotropic jamming point, when the material is subject to a sufficiently large shear strain, γ_SJ, starting from a force-free state. Here we report experimental studies on the system size dependence for a quasi-2D frictional system composed of bidisperse photoelastic disks. The number of particles in the system ranges from 60 to 3000 by varying particle diameters while maintaining the number and size ratio between big and small disks the same. We observe that γ_SJ increases with system size at the same Φ for systems with less than 1000 particles, reminiscent of a recent simulation work (Baity-Jesi et al., J. Stat. Phys. 167, 735 (2017)). However, such a dependence is much weaker comparing systems with 1000 and 3000 particles. Our results imply that SJ still exists in frictional granular materials in the thermodynamic limit.