Multiple equilibria in a simple elastocapillary system

Journal article

We consider the elastocapillary interaction of a liquid drop placed between two flexible sheets, which are both clamped at one end to a rigid substrate. This is a simple model system relevant to the problem of surface tension-induced collapse of flexible micro-channels that has been observed in the manufacture of microelectromechanical systems(MEMS). We determine the conditions under which the flexible sheets remain separated, touch at a point, or stick along a portion of their length. Surprisingly, we show that in many circumstances multiple equilibrium states are possible. We develop a lubrication-type model for the flow of liquid out of equilibrium and thereby investigate the stability of the multiple equilibria. We demonstrate that for given material properties two stable equilibria may exist and show through numerical solutions of the dynamic model that it is the initial state of the system that determines which stable equilibrium is reached by the system; the system does not simply choose the equilibrium state of lowest energy.

Authors: Taroni, M; Vella, D

• Publication date: 2012-01-01