title: Pattern formation during deformation of a confined viscoelastic layer: from a viscous liquid to a soft elastic solid.
abstract: We study pattern formation during tensile deformation of confined viscoelastic layers. The use of a model system [poly(dimethylsiloxane) with different degrees of cross-linking] allows us to go continuously from a viscous liquid to an elastic solid. We observe two distinct regimes of fingering instabilities: a regime called "elastic" with interfacial crack propagation, where the fingering wavelength scales only with the film thickness, and a bulk regime called "viscoelastic," where the fingering instability shows a Saffman-Taylor-like behavior. We find good quantitative agreement with theory in both cases and present a reduced parameter describing the transition between the two regimes and allowing us to predict the observed patterns over the whole range of viscoelastic properties.
authors.affiliation: Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), UMR 7636, CNRS - ESPCI - Universités Paris 6 et 7, 10, rue Vauquelin, 75231 Paris Cedex 05, France.
authors.forename: Julia
authors.initials: J
authors.lastname: Nase
authors.forename: Anke
authors.initials: A
authors.lastname: Lindner
authors.forename: Costantino
authors.initials: C
authors.lastname: Creton