Folding Energetics in Thin-Film Diaphragms

We perform experiments on thin-film diaphragms to show that the folding patterns of anisotropically compressed diaphragms are strikingly different from those of isotropically compressed ones. We then use a simple von Karman model to relate the overall features of these folding patterns to the underlying energetics. We show that the differences between the isotropic and anisotropic cases can be traced back to fundamental changes in the energy structure of the diaphragms. Finally, we point out that the energy structure of thin-film diaphragms is similar to that of many other systems in physics and engineering, into which our study may provide interesting insights.