title: Anisotropic blistering instability of highly ellipsoidal shells.
abstract: The formation of localized periodic structures in the deformation of elastic shells is well documented and is a familiar first stage in the crushing of a spherical shell such as a ping-pong ball. While spherical shells manifest such periodic structures as polygons, we present a new instability that is observed in the indentation of a highly ellipsoidal shell by a horizontal plate. Above a critical indentation depth, the plate loses contact with the shell in a series of well-defined "blisters" along the long axis of the ellipsoid. We characterize the onset of this instability and explain it using scaling arguments, numerical simulations, and experiments. We also characterize the properties of the blistering pattern by showing how the number of blisters and their size depend on both the geometrical properties of the shell and the indentation but not on the shell's elastic modulus. This blistering instability may be used to determine the thickness of highly ellipsoidal shells simply by squashing them between two plates.
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Hamid
authors.initials: H
authors.lastname: Ebrahimi
authors.affiliation: Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Amin
authors.initials: A
authors.lastname: Ajdari
authors.affiliation: Mathematical Institute, University of Oxford,Woodstock Road, Oxford OX2 6GG, United Kingdom.
authors.forename: Dominic
authors.initials: D
authors.lastname: Vella
authors.affiliation: Laboratoire Reproduction et Développement des Plantes & Laboratoire Joliot-Curie, INRA, CNRS, ENS, Université de Lyon, 46 Allée d'Italie, F-69364 Lyon Cedex 07, France.
authors.forename: Arezki
authors.initials: A
authors.lastname: Boudaoud
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Vaziri
mesh_terms: D003198:Computer Simulation; D004548:Elasticity; D008422:Materials Testing / Q000379:methods*; D008962:Models, Theoretical; D010969:Plastics / Q000737:chemistry*
chemical_list: D010969:Plastics