Gravity and surface tension effects on the shape change of soft materials

Surface tension and gravity, whose influence on the deformation of conventional engineering materials is negligible, become important for soft materials that are typically used in the microfabrication of devices such as microfluidic channels. Although for soft materials the shape change due to these forces can be large, it is often neglected in the design processes. To capture conditions under which the influence of these forces is important, we propose a deformation map in which the shape change is captured by two dimensionless material parameters. Our idea is demonstrated by simulating the large deformation of a short circular cylinder made of a neo-Hookean material in frictionless contact with a rigid substrate. These simulations are carried out using a finite element model that accounts for surface tension and gravity. Our model integrates the two different approaches typically used to determine the shape change of solids and liquid drops in contact with a substrate.