Characterizing dynamic load propagation in cohesionless granular packing using force chain

When dynamic load is applied on a granular assembly, the time-dependent dynamic load and initial static load (such as gravity stress) act together on individual particles. In order to better understand how dynamic load triggers the micro-structure`s evolution and furtherly the ensemble behavior of a granular assembly, we propose a criterion to recognize the major propagation path of dynamic load in 2D granular materials , called the “dynamic force chain”. Two steps are involved in recognizing dynamic force chains: (1) pick out particles with dynamic load larger than the threshold stress, where the attenuation of dynamic stress with distance is considered; (2) among which quasi-linear arrangement of three or more particles are identified as a force chain. The spatial distribution of dynamic force chains in indentation of granular materials provides a direct measure of dynamic load diffusion. The statistical evolution of dynamic force chains shows strong correlation with the indentation behaviors.