  A folded disk is bistable, as it can be popped through to an inverted state
with elastic energy localized in a small, highly-deformed region on the fold.
Cutting out this singularity relaxes the surrounding material and leads to a
loss of bistability when the hole dimensions reach a critical size. These
dimensions are strongly anisotropic and feature a surprising re-entrant
behavior, such that removal of additional material can re-stabilize the
inverted state. A model of the surface as a wide annular developable strip is
found to capture the qualitative observations in experiments and simulations.
These phenomena are consequential to the mechanics and design of crumpled
elastic sheets, developable surfaces, origami and kirigami, and other
deployable and compliant structures.
