The bendo-capillary length of a flexible sheet is defined as:
where
B is the bending modulus of an elastic material.
γ is the surface tension of a liquid.
This provides a comparison between bending stiffness (elasticity) and surface tension (capillarity). An elastic structure will be significantly deformed once its length is larger than the elasto-capillary length, which can be explained when gain of surface energy of a material is larger than stored elastic energy while bending.