Shear Jamming of Frictional Grains under Oscillatory Shear

Granular materials have rigidity above a critical density [1]. It is well-known that frictionless grains under small strain exhibit a continuous transition of the shear modulus G, while recent studies have revealed that G of frictional grains with harmonic repulsive interaction discontinuously emerges at the critical density [2].
In this talk, we present our recent numerical results on the shear modulus of frictional grains under oscillatory shear. It is confirmed that the shear modulus depends on the amplitude of the initial oscillatory shear before the mesurament. Even at densities below the transition point, where isotropic jamming occurs without shear, the initial oscillatory shear can induce the finite shear modulus. This behavior is consistent with a transition known as shear jamming [3]. We also discuss the evolution of the force chain network under the initial oscillatory shear and the conection with the discontinuous shear thickenning.

[1] M. van Hecke, J. Phys.: Condens. Matter 22, 033101 (2009).
[2] M. Otsuki and H. Hayakawa, Phys. Rev. E 95, 062902 (2017).
[3] D. Bi, J. Zhang, B. Chakraborty, and R. Behringer, Nature (London)
480, 355 (2011).