Wrapping an adhesive sphere with an elastic sheet.

We study the adhesion of an elastic sheet on a rigid spherical substrate. Gauss's Theorema Egregium shows that this operation necessarily generates metric distortions (i.e., stretching) as well as bending. As a result, a large variety of contact patterns ranging from simple disks to complex branched shapes are observed as a function of both geometrical and material properties. We describe these different morphologies as a function of two nondimensional parameters comparing, respectively, bending and stretching energies to adhesion. A complete configuration diagram is finally proposed.