Influence of Eccentricity on Induced Anisotropy of Granular Media

There is a close cross-scale relationship between fabric anisotropy of granular media and the macro-mechanical properties, and particle shape plays a significant role in the evolution of the fabric anisotropy. In addition to sphericity, angularity and roughness of particles, the authors found that the eccentricity in the particle morphology is also an important factor, and there were few studies on it so far. So in this paper, the open source aspheric DEM program SudoDEM was used to model eccentric particles based on poly-superellipsoids. A series of true triaxial simulations with different eccentricities were carried out, and the effects of eccentricity on the induced anisotropy of granular media were explored. The results show that the fabric anisotropy develops to varying degrees with the increase of eccentricity, leading to the development of macroscopic shear resistance of granular media. Meanwhile, the coordination number is larger, the proportion of sliding contacts is higher, and the grid inhomogeneity of the contact force is more obvious. This is mainly because the particle eccentricity enhances the interlocking between particles. Normal contact force has the largest weight in the induced anisotropy, while the normal branch vector remains basically isotropic. Anisotropy of tangential contact force and tangential branch vector are rather sensitive to the eccentricity, indicating that contribution of them to fabric anisotropy cannot be ignored. The increased weak contact and sliding contact proportions caused by the increased eccentricity also indirectly lead to transformation between the normal contact force anisotropy and tangential contact force anisotropy.