  Bistable structures associated with non-linear deformation behavior,
exemplified by the Venus flytrap and slap bracelet, can switch between
different functional shapes upon actuation. Despite numerous efforts in
modeling such large deformation behavior of shells, the roles of mechanical and
nonlinear geometric effects on bistability remain elusive. We demonstrate,
through both theoretical analysis and table-top experiments, that two
dimensionless parameters control bistability. Our work classifies the
conditions for bistability, and extends the large deformation theory of plates
and shells.
