Scaling behavior of cohesive self-gravitating aggregates

Emilien Azéma (1, 2) , Paul Sánchez (3) , Daniel J. Scheeres (3)

1 LMGC - Laboratoire de Mécanique et Génie Civil
2 PMMD - Physique et Mécanique des Milieux Divisés
3 University of Colorado [Boulder]

By means of extensive three-dimensional contact dynamics simulations, we analyze the strength properties and microstructure of a granular asteroid, modeled as a self-gravitating cohesive granular aggregate composed of spherical particles, and subjected to diametrical compression tests. We show that, for a broad range of system parameters (shear rate, cohesive forces, asteroid diameter), the behavior can be described by a modified inertial number that incorporates interparticle cohesion and gravitational forces. At low inertial numbers, the behavior is ductile with a well-defined stress peak that scales with internal pressure with a prefactor 0.9. As the inertial number increases, both the prefactor and fluctuations around the mean increase, evidencing a dynamical crisis resulting from the destabilizing effect of particle inertia. From a micromechanical description of the contact and force networks, we propose a model that accounts for solid fraction, local stress, particle connectivity, and granular texture. In the limit of small inertial numbers, we find a very good agreement of the theoretical estimate of compressive strength, evidencing the major role of these structural parameters for the modeled aggregates.

Mots clés: Granular Asteroid; DEM; Scaling

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des solides [physics.class-ph]

Emilien Azéma, Paul Sánchez, Daniel J. Scheeres. Scaling behavior of cohesive self-gravitating aggregates. Physical Review E , 2018, 98 (3), ⟨10.1103/PhysRevE.98.030901⟩. ⟨hal-01873746⟩