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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 4: Interfaces and Thin Films

CPP 4.7: Talk

Monday, March 18, 2024, 11:00–11:15, H 0111

Elastic Capsules in Contact — •Felix Kratz and Jan Kierfeld — TU Dortmund

Contact phenomena between soft or elastic bodies are ubiquitous in nature. They are encountered in problems across the scales and include important biological processes, such as cell interactions, as well as medical applications e.g. angioplasty and drug delivery. An important hallmark in the understanding of contact mechanics is the Hertz-problem, studied and solved by Heinrich Hertz in 1881. It predicts the contact properties of bulk elastic bodies without adhesion or friction. While the contact between two bulk elastic objects is well understood by this theory, the understanding of thin-walled and pressurised elastic objects is still evolving. In this work we want to explore the contact mechanics of two thin walled, pressurised adhesive elastic capsules -- with and without bending stiffness -- suspended from two opposing capillaries and pressed against each other by an external force. The theoretical investigation is performed in terms of variational calculus of the appropriate free energy. We differentiate between free-slip and no-slip contact boundary conditions and derive the full set of shape and contact equations independent of the elastic constitutive law. Finally, we integrate the resulting shape equations numerically and analyse the parameter-shape-space and the force-contact-length relationship.

Keywords: capsule; elasticity; contact; adhesion; bending