Annealing glasses by cyclic shear deformation and vibration modeled by a 2-D granular system: study of the effect of shear amplitude

This work proposes a slightly tilted bidimensional vibrated hard-sphere system, periodically sheared via deformations, for modeling glass to crystal transitions. Specifically, the system, initially in random closed packed (RCP) state modeling an amorphous solid, rearranges into a hexagonal closed packed (HCP) crystal configuration. The vibration is fixed in amplitude and frequency, so it models a constant temperature. The shearing is achieved by periodical deformations of a deformable rhomboidal shape boundary based on a four-bar mechanism. To measure the time evolution of the annealing, the sixth-bond-orientational-order parameter $\psi_{6}\’$ is measured during 42 cycles of shearing. We report the results of 7 experimental cases where the maximum deformation shear amplitude is varied. We found correlations between shear amplitude with the average of the sixth-bond-orientational-order parameter. The results indicate complex oscillatory hexagonal order dynamics determined by the cyclic perturbation. These oscillations are analyzed by first and second-order linear regressions finding correlations between the sheared boundary's acceleration with the rate of change of $\psi_{6}\’$. Furthermore, images of the hexagonal crystal grains during its annealing are presented.