Quasistatic rheology of foams: II. Continuous shear flow

Alexandre Kabla (1) , Julien Scheibert (2) , Georges Debregeas (2)

1 SEAS - Harvard John A. Paulson School of Engineering and Applied Sciences
2 LPS - Laboratoire de Physique Statistique de l'ENS

The evolution of a bidimensional foam submitted to continuous quasistatic shearing is investigated both experimentally and numerically. We extract, from the images of the sheared foam, the plastic flow profiles and the modifications of the stress field. As the imposed strain becomes larger than the yield strain, a shear-banding transition is observed leading to a spatially confined flow profile. This process is associated with a sudden increase in the temporal and spatial correlations of the plastic events. The spatial fluctuations of the static stress field is measured in different regions of the sample: the shear-band region is found to exhibit larger stress heterogeneities than the rest of the sample. This property can be associated with a decrease in the effective yield stress so that the shear-banding process can be understood as a strain-weakening instability. Furthermore, we investigate the stress fluctuations associated with the plastic rearrangements in the permanent regime of flow.

Mots clés: foam; rheology

Domaines: Matière Molle [cond-mat.soft]

Alexandre Kabla, Julien Scheibert, Georges Debregeas. Quasistatic rheology of foams: II. Continuous shear flow. 2006. ⟨hal-00076563⟩