Wrinkles, folds, and plasticity in granular rafts

Etienne Jambon-Puillet (1) , Christophe Josserand (2) , Suzie Protiere (2)

1 DALEMBERT - Institut Jean Le Rond d'Alembert
2 IJLRDA-FCIH - Fluides Complexes et Instabilités Hydrodynamiques

We investigate the mechanical response of a compressed monolayer of large and dense particles at a liquid-fluid interface: a granular raft. Upon compression, rafts first wrinkle; then, as the confinement increases, the deformation localizes in a unique fold. This characteristic buckling pattern is usually associated with floating elastic sheets, and as a result, particle laden interfaces are often modeled as such. Here, we push this analogy to its limits by comparing quantitative measurements of the raft morphology to a theoretical continuous elastic model of the interface. We show that, although powerful to describe the wrinkle wavelength, the wrinkle-to-fold transition, and the fold shape, this elastic description does not capture the finer details of the experiment. We describe an unpredicted secondary wavelength, a compression discrepancy with the model, and a hysteretic behavior during compression cycles, all of which are a signature of the intrinsic discrete and frictional nature of granular rafts. It suggests also that these composite materials exhibit both plastic transition and jamming dynamics.

Domaines: Mécanique des fluides [physics.class-ph]

Etienne Jambon-Puillet, Christophe Josserand, Suzie Protiere. Wrinkles, folds, and plasticity in granular rafts. Physical Review Materials, 2017, 1 (4), ⟨10.1103/PhysRevMaterials.1.042601⟩. ⟨hal-02172351⟩