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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Poster Session III
CPP 33.26: Poster
Dienstag, 13. März 2018, 14:00–16:00, Poster C
Cusp-Shaped Elastic Creases and Furrows — •Stefan Karpitschka1,2, Jens Eggers3, Anupam Pandey1, and Jacco H. Snoeijer1,4 — 1Physics of Fluids Group, Faculty of Science and Technology, University of Twente, Enschede, Netherlands — 2Max Planck Institute for Dynamics and Self-Organization, Göttingen — 3School of Mathematics, University of Bristol, United Kingdom — 4Mesoscopic Transport Phenomena, Eindhoven University of Technology, Netherlands
The surfaces of growing biological tissues, swelling gels, and compressed rubbers do not remain smooth, but frequently exhibit highly localized inward folds. In biology, such elastic structures are called sulci, which are prime morphological features of human brains and growing tumors. Yet in spite of their ubiquity and importance, a quantitative theoretical description of the morphology of localized indentations is still missing. We reveal the morphology of this surface folding in a novel experimental setup, which permits us to deform the surface of a soft gel in a controlled fashion [Phys. Rev. Lett. 119, 198001 (2017)]. The interface first forms an increasingly sharp furrow. Above a critical deformation, the furrow bifurcates to an inward folded crease of vanishing tip size. We show experimentally and numerically that both creases and furrows exhibit a universal cusp shape, whose width scales like y3/2 at a distance y from the tip. We provide a similarity theory that captures the singular profiles before and after the self-folding bifurcation, and derive the length of the fold from finite deformation elasticity.