The strain energy density of rubber-like shells

Abstract Under the assumption that the state of a shell is described by the change in the first and second fundamental forms of its midsurface from an initially elastic isotropic state, an approximate strain energy density is derived, first using strictly two-dimensional arguments and then by descent from three dimensions assuming incompressibilily. To within errors inherent in shell theory itself, it is shown that the strain energy density is the same as that of a plate of the same material.