Local responses in 2D assemblies of elliptical rods when subjected to biaxial shearing

Abstract

This study explored the characteristics of local responses in 2D assemblies of elliptical particles when subjected to shearing. A biaxial shearing system was designed for this investigation, and two assemblies of elliptical rods with different eccentricities were used. To quantify the local responses, the assemblies were partitioned into individual Set Voronoi cells, and in this partition, the scaling method was proposed to tackle the interparticle overlapping problem. Then, in the Voronoi cells, the local strain was measured, accounting for the effect of interparticle rotation, and the local structures in terms of the local volume and anisotropy were estimated using Minkowski functionals. In the two samples, discontinuity by shearing was observed for these local quantities. Before the peak stress, the local strain developed randomly and the local volume followed a k-gamma distribution. After shearing, shear band and a mixed k-gamma distribution of the local volume emerged. For the local anisotropy, the variation inside shear band was significantly increased by shearing. Finally, the responses inside and outside the shear band were taken out separately for analysis, and the free-volume model was used to explain the differences between these two regions.