Contact mechanics of a gel under constrained swelling

摘要

Gels have been widely explored in many engineering applications, in which they often swell with mechanical constraints. In this paper, we study mechanics of contact between a constrained swelling gel and a rigid spherical probe. We first derive an analytical form of the surface Green's function of a laterally constrained swelling gel occupying a half space. We then obtain an analytical form of the relationship between the indentation force and indentation depth for a spherical rigid indenter pressing onto a laterally constrained swelling gel, with and without taking account of the adhesion. Our theory also uncovers the influences of the constrained swelling ratio of the gel on the contact area (as well as its eccentricity), pull-off force and critical distance at separation. The essential parts of the analytical results are validated by finite element simulations. The results obtained in this article may help to better interpret experimental measurements from indentation tests of swollen gels. (C) 2018 Elsevier Ltd. All rights reserved.