Effect of aspect ratio on triaxial compression of multi-sphere ellipsoid assemblies simulated using a discrete element method

• Published in: Particuology Vol. 32; no. 3; pp. 49 - 62
• Main Authors: Gong, Jian, Liu, Jun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2017
• Subjects: Aspect ratio; DEM; Ellipsoids; Macro-micro response; Particle shape; Triaxial compression; 三维离散元法; 三轴压缩; 临界状态; 力学行为; 各向异性系数; 椭球体; 离散元模拟; 纵横比; Triaxial compression; Particle shape; Aspect ratio; DEM; Ellipsoids; Macro-micro response
• ISSN: 1674-2001; 2210-4291
• DOI: 10.1016/j.partic.2016.07.007

Here, we present a numerical investigation of the mechanical behavior of ellipsoids under triaxial com- pression for a range of aspect ratios. Our simulations use a multi-sphere approach in a three-dimensional discrete element method. All assemblies were prepared at their densest condition, and triaxial compres- sion tests were performed up to extremely large strains, until a critical state was reached. The stress-strain relationship and the void ratio-strain behavior were evaluated. We found that the stress-dilatancy rela- tionship of ellipsoids with different aspect ratios could be expressed as a linear equation. In particular, the aspect ratio influenced the position of the critical state lines for these assemblies. Particle-scale char- acteristics at the critical state indicate that particles tend to be flat lying, and the obstruction of particle rotation that occurs with longer particles affects their contact mechanics. Lastly, anisotropic coefficients related to aspect ratio were investigated to probe the microscopic origins of the macroscopic behavior. A detailed analysis of geometrical and mechanical anisotropies revealed the microscopic mechanisms underlying the dependency of peak and residual strengths on aspect ratio.