Shape-shifting of polymer beams and shells due to oil extraction

We investigate the morphing of bilayer naturally curved beams and cylindrical shells due to oil extraction from the outer layers. We fabricate bilayer naturally curved beams and cylindrical shells made of PDMS/(PDMS + silicone oil), use the experimental results to validate an explicit formula delivering the change in curvature of the beams, based on the modeling of oil extraction as a bulk contraction. We show as the same model, set up within a 3D context, delivers the morphing of bilayer cylindrical shells and identify potentially interesting results for designing future experiments. In particular, we show as stable states corresponding to the original cylindrical shells can be got in the form of saddle-like shells and cylindrical shells with the axes of principal curvatures switched with respect to the original axes.