Surface wrinkling

Figure 31.2. Schematic of generating wrinkles on a stiff skin adhered to a soft substrate. The laminate undergoes wrinkling upon compressive strain from an initial length (L) to a final length (L- ΔL). Examples of 1-dimensional and 2-dimensional wrinkling patterns and methods for measuring their wavelength.

Here we will consider buckling instability of a sandwiched system comprising of a thin laminate made of a stiffer material attached to a soft substrate. When a compressive load is applied at the ends of the sandwiched system wrinkles with well defined wavelength and amplitude begin to appear. The wavelength of the instability, , remains linearly dependent on the thickness  of the laminate, . Additionally, the amplitude of the wrinkles  increases nonlinearly with strain  as .