Wrinkling and creasing of a compressed elastoplastic film resting on a soft substrate

We reveal an interesting postbuckling phenomenon of an elastoplastic film resting on a soft substrate under in-plane compression. Finite element simulations show that with the increase in the applied compressive strain, the film first undergoes global sinusoidal wrinkling, followed by localized creasing. The physical mechanism underlying this transition lies mainly in the competition between elastic strain energy and plastic dissipation. The corresponding critical conditions of plastic yielding and localized creasing of the wrinkled film are given via theoretical analysis and numerical simulations. The reported results may facilitate the use of buckling-based technique to fabricate controlled surface patterns with desired physical properties.