Uncovering temporal transitions and self-organization during slow aging of dense granular media in the absence of shear bands

Abstract

We present a method for discovering temporal transitions in the macroscopic response of two granular assemblies of photoelastic disks, subject to prolonged symmetric cyclic pure shear - under uniform deformation. A distance-matrix- based analysis is used in a reconstructed state space formed from the macroscopic stress ratio time series, with the technique of quadrant scans applied to extract transition times from the recurrence plots. Macroscopic measures of pressure and shear stress exhibit limit cycle behavior with respect to the applied cyclic strain. The contact network and the strong force filamentary network, however, show a gradual change across shear cycles. A quantitative character..