title: Rheology of three-dimensional packings of aggregates: microstructure and effects of nonconvexity.
abstract: We use three-dimensional contact dynamics simulations to analyze the rheological properties of granular materials composed of rigid aggregates. The aggregates are made from four overlapping spheres and described by a nonconvexity parameter depending on the relative positions of the spheres. The macroscopic and microstructural properties of several sheared packings are analyzed as a function of the degree of nonconvexity of the aggregates. We find that the internal angle of friction increases with the nonconvexity. In contrast, the packing fraction first increases to a maximum value but declines as the nonconvexity increases further. At a high level of nonconvexity, the packings are looser but show a higher shear strength. At the microscopic scale, the fabric and force anisotropy, as well as the friction mobilization, are enhanced by multiple contacts between aggregates and interlocking, thus revealings the mechanical and geometrical origins of shear strength.
authors.affiliation: Université Montpellier 2, CNRS, LMGC, Cc 048, Place Eugène Bataillon, F-34095 Montpellier Cedex 05, France. emilien.azema@univ-montp2.fr
authors.forename: Emilien
authors.initials: E
authors.lastname: Azéma
authors.forename: Farhang
authors.initials: F
authors.lastname: Radjaï
authors.forename: Baptiste
authors.initials: B
authors.lastname: Saint-Cyr
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Delenne
authors.forename: Philippe
authors.initials: P
authors.lastname: Sornay
mesh_terms: D003102:Colloids / Q000737:chemistry*; D003198:Computer Simulation; D017276:Friction; D008956:Models, Chemical; D008958:Models, Molecular; D012212:Rheology / Q000379:methods*; D033081:Shear Strength
chemical_list: D003102:Colloids