Nase Julia, Lindner Anke, Creton Costantino
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.
Phys Rev Lett. 2008 Aug 15;101(7):074503. doi: 10.1103/PhysRevLett.101.074503. Epub 2008 Aug 14.
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.
我们研究受限粘弹性层拉伸变形过程中的图案形成。使用模型体系（具有不同交联度的聚二甲基硅氧烷）使我们能够连续地从粘性液体转变为弹性固体。我们观察到两种不同的指进不稳定性状态：一种称为“弹性”状态，伴有界面裂纹扩展，其中指进波长仅与薄膜厚度成比例；另一种是称为“粘弹性”的体相状态，其中指进不稳定性呈现类似萨夫曼 - 泰勒的行为。我们发现这两种情况在定量上都与理论有很好的一致性，并提出了一个简化参数来描述两种状态之间的转变，使我们能够在整个粘弹性性质范围内预测观察到的图案。
