Effects of particle shape irregularity on the microstructure of granular materials

¹ LMGC, University of Montpellier, CNRS, 163 rue Auguste Broussonnet, 34090 Montpellier, France
² Inhytech, HEC, Hanoi University of Civil Engineering, 55 Giai Phong street, Hanoi, Vietnam
³ CEA, DES, IRESNE, DEC, Cadarache, F 13108 Saint Paul lez Durance, France

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 1 December 2025

Abstract

We use 3D simulations by discrete element method to explore the effects of particle-to-particle shape irregularity on the microstructure and force transmission in granular packings. Using modified icosahedra with a controlled degree of irregularity, we prepare large frictionless samples by isotropic compaction. We show that local order decreases with increasing shape irregularity, as evidenced by a flattened first peak in the radial distribution function while the mean inter-particle distance for nearest neighbors remains stable. Furthermore, while the samples are isostatic, the contact network topology varies with shape irregularity: the proportion of stabilizing face-face contacts decreases while weaker single contacts become more prevalent. This structural change leads to an increase in force network inhomogeneity, evidenced by a broader probability distribution of normal contact forces with a larger population carrying weak forces. These combined microstructural changes suggest potential consequences for the macroscopic mechanical response under shear, such as a possible decline in the internal friction coefficient. This work underscores the critical role of statistical shape variability in controlling granular fabric and force transmission, offering insights for modeling natural and engineered granular materials.