8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.87Deformation and buckling of elastic capsulesSebastian Knoche 1 and Jan Kierfeld 11 TU Dortmund, Otto-Hahn-Str. 4, 44221, Dortmund, GermanyWe investigate the deformation behavior of soft elastic capsules. Based on nonlinear shell theory,a theoretical model for liquid filled capsules hanging from a capillary in a pendant drop geometryis developed, and shape equations are derived. Their deformation behavior upon (a) changinggravity forces (by changing the density contrast between liquids) and (b) reducing capsule volumeis analyzed numerically. In case (a), the capsule stretches and sags and in case (b) we find arich bifurcation behavior between buckled shapes; the preferred configurations are deduced froma least-energy principle. Based on theoretical results we develop a fitting procedure, which allowsus to extract the elastic moduli of the capsule membrane from experimental data. We use similarmethods to analyze the buckling behavior of spherical capsules upon reduction of the capsulevolume. By preventing self-intersection for strongly reduced volume, we obtain a complete pictureof the buckling process and can follow the transition from the undeformed configuration into thefully buckled state.87