Pursing of planar elastic pockets

The pursing of a simply- or doubly-connected planar elastic pocket by an applied pressure is analysed from the bending to the stretching regimes. The response is evaluated in terms of maximum deflection and profiles across a range of simply- and doubly-connected circular and square shapes. The study is conducted using experimental and numerical methods and supported by previous analytical results. The experimental method is based on an original 2D optical method that gives access to the pursing direction perpendicular to each image across the field of view. The equations for maximum pursing deflections are developed and compared for a range of thicknesses of silicone samples and shapes from the bending to the stretching regimes. In the case of doubly-connected shapes, dependence of maximum pursing deflection on clamped central circular and square areas or holes is quantified for both regimes. Good agreement is established between the three methods and the study also shows that the optical method may as well be successfully applied to problems of pursing of rubber pockets.