Influence of aspect ratio and arrangement direction on the shear behavior of ellipsoids--颗粒学报PARTICUOLOGY

Sun, W., Wu, K., Liu, S., & Zhang, X. (2022). Influence of aspect ratio and arrangement direction on the shear behavior of ellipsoids. Particuology, 70, 82-94. https://doi.org/10.1016/j.partic.2022.01.005

Influence of aspect ratio and arrangement direction on the shear behavior of ellipsoids

Weichen Sun ^a, Kai Wu ^b *, Songyu Liu ^b, Xiang Zhang ^b

a School of Civil Engineering, Chongqing University, Chongqing 400045, China
b School of Transportation, Southeast University, Nanjing 210096, China

10.1016/j.partic.2022.01.005

Volume 70, November 2022, Pages 82-94

Received 2 October 2021, Revised 23 December 2021, Accepted 5 January 2022, Available online 21 January 2022, Version of Record 14 February 2022.

E-mail: wukai2018@seu.edu.cn

Highlights

• Shear behavior of ellipsoids is studied using 3D DEM simulation.

• Aspect ratio is an important factor affecting strength of ellipsoidal specimens.

• Initial arrangement direction has an obvious effect on strength of ellipsoids.

• Macroscopic and microscopic analysis under various conditions is carried out.

Abstract

This work studies the macroscopic and microscopic behaviors of ellipsoids under triaxial tests using 3D discrete element method (DEM) simulation. To avoid the boundary effect, a novel stress servo-controlled periodic boundary condition is proposed to maintain the confining pressure of samples during testing. The shape features of ellipsoids are investigated, including the aspect ratio of elongated/oblate ellipsoids and the initial arrangement directions of ellipsoids. The macroscopic properties of ellipsoidal particle samples, such as the deviatoric stress, volumetric strain, internal friction angle, as well as dilatancy angles are explored. Elongated and oblate ellipsoids with varying aspect ratios are investigated for the occurrence of stick-slips. In addition, it is demonstrated that the initial arrangement direction has a significant impact on the coordination number and contact force chains. The corresponding anisotropy coefficients of the entire contact network are analyzed to probe the microscopic roots of macroscopic behavior.

Graphical abstract

Keywords

DEM; Shear; Ellipsoid; Periodic boundary condition; Arrangement direction; Aspect ratio

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