MOLECULAR-DYNAMICS SIMULATION OF CONTACT AND FORCE NETWORKS IN FRAGMENTED SEA ICE UNDER SHEAR DEFORMATION

Fragmented sea ice can be treated as a strongly polydisperse granular material consisting of approximately disk-shaped grains (ice floes) with power-law size distribution, moving on a two-dimensional sea surface under the influence of external forces (wind, currents, etc.). In this paper, a molecular-dynamics model is used to study the internal stress and the properties of the force networks in sea ice subject to pure shear strain (constant ice concentration). The model exhibits a wide range of behaviors analogous to those observed recently in bidisperse materials, including shear-jammed and fragile states. At certain combinations of ice concentration and strain, the modeled system behaves erratically and undergoes rapid shifts between the jammed and unjammed states, resulting in strong variability in its global characteristics, e.g., the area-average stress and anisotropy of the force networks.