The influence of particle shape on the rheology and texture of granular media has been the subject of several and intense numerical studies with irregular polyhedral, flattened (platelets), non-convex 3D particles. These studies have been carried out either in collaboration with the University of Los Andes de Bogota or under industrial contracts with the CEA. A basic result is that the shear strength varies non-linearly with the packing fraction as the shape deviates from that of a sphere. This variation was explained to subtle compensations between the frictional anisotropy (presence of complex contacts depending on the shape), and geometric compensation induced by the orientation of the particles or faces of the grains in contact. Moreover, sine the local order is strongly modified by the shape, we have shown that the weak force network, which stabilizes the force chains in disc packing, progressively transforms into an active network with regard to the transmission of forces. An other major result obtained via an energetic criterion was to quantitatively match a rolling friction (quantifying the hindering of rotations) to each degree of angularity. In collaboration with Chiang Mai University in Thailand we have extended the studies to granular mixtures by shape. A surprising result is that the resistance is independent of the homogeneity of the system whereas it is sensitive to the nature of the mixture.
Effects of particle shape angularity:
5] Force transmission in a packing of pentagonal particles, Phys.Rev. E 2007
4] Quasistatic rheology, force transmission and fabric properties of a packing of irregular polyhedral particles, Mech. Mat. 2009
3] Identification of rolling resistance as a shape parameter in sheared granular media, Phys. Rev. E 2011
2] Nonlinear effects of particle shape angularity in sheared granular media, Phys. Rev. E 2012
1] Packings of irregular polyhedral particles: Strength, structure, and effects of angularity, Phys. Rev. E 2013
Effects of particle shape elongation/platyness
4] Stress-strain behavior and geometrical properties of packings of elongated particles, Phys. Rev. E 2010
3] Force chains and contact network topology in sheared packings of elongated particles, Phys. Rev. E 2012
2] Quasistatic rheology and microstructural description of sheared granular materials composed of platy particles, Phys. Rev. 2013
1] Particle alignment and clustering in sheared granular materials composed of platy particles, Eur. Phys. J. E 2014
Effect of particle shape non-convexity
1] Rheology of three-dimensional packings of aggregates: Microstructure and effects of nonconvexity, Phys. Rev. E 2013
Mixture by particle shape
2] Binary mixtures of disks and elongated particles: Texture and mechanical properties, Phys. Rev. 2016
1] Effects of particle shape mixture on strength and structure of sheared granular materials, Phys. Rev. E 2019