Abstract
Gels are used to design bilayered structures with high residual stresses. The
swelling of a thin layer on a compliant substrate leads to compressive stresses.
The post-buckling of this layer is investigated experimentally; the wavelengths
and amplitudes of the resulting modes are measured. A simplified model with a
self-avoiding rod on a Winkler foundation is in semi-quantitative agreement with
experiments and reproduces the observed cusp-like folds.