Buckling of a synthetic film
= Buckling of a synthetic film
{title2=$\kappa q^4+\sigma q^2<0$}
A flat, unsupported film's bending and <tension> energies give modal stiffness $\kappa q^4+\sigma q^2$. Negative <tension> represents compression, destabilizing sufficiently long waves. A finite sheet restricts allowed <wave numbers>, while a supporting foundation adds stiffness and can select a wrinkle wavelength. This is generic continuum mechanics, independent of biological membrane structure.