Shear jamming, DST and fragile of frictional granular materials under oscillatory shear*

The mechanical response of two-dimensional frictional granular
materials under an oscillatory
shear in a constant volume are numerically investigated. It is
confirmed that the shear storage modulus G′ depends
on the initial amplitude of the oscillation to prepare the system
before the measurement. For
sufficiently large initial strain amplitude, the shear jammed state
satisfying G′ > 0 is observed even
if the packing fraction is below the jamming point. The fragile state
is also identified as a long lived
metastable state where G′ depends on the phase of the oscillatory
shear. The dynamic viscosity
evaluated from the shear loss modulus G′′ exhibits a sudden jump
similar to the discontinuous shear
thickening in the fragile state.[1]

In this talk we also show some preliminary results of hydrodynamic
simulation for colloidal suspensions
to discuss shear jamming and DST as well as the behavior of dry
granular particles under the pressure
control protocol.

[1] M. Otsuki and H. Hayakawa, arXiv:1810.03846.