  A rectangular thin elastic sheet is deformed by forcing a contact between two
points at the middle of its length. A transition to buckling with stress
focusing is reported for the sheets sufficiently narrow with a critical width
proportional to the sheet length with an exponent 2/3 in the small thickness
limit. Additionally, a spring network model is solved to explore the thick
sheet limit and to validate the scaling behaviour of the transition in the thin
sheet limit. The numerical results reveal that buckling does not exist for the
thickest sheets and a stability criterion is established for the buckling of a
curved sheet.

Soft Condensed Matter