Event

Soft elastic solids placed under compressive stress can undergo a variety of geometry-dependent mechanical shape instabilities, providing opportunities for tailoring the structure and properties of stimuli-responsive materials. In one example, we study the surface ‘creasing’ instability of thin layers confined in two-dimensions by attachment to a more rigid foundation. In close analogy to classical nucleation theory, formation of creases requires a finite overstrain to overcome the energy barrier provided by surface tension, thus yielding sensitivity to heterogeneous nucleation sites, and allowing for control over crease locations by the introduction of nucleating features. In a second example, we consider the behavior of gel sheets with internal patterns of growth provided by lithographically defined lateral variations in crosslinking. We study how thin sheets with sharp changes in swelling deform in 3D to balance bending and stretching energies, and how patterns on length-scales comparable to the film thickness yield locally smooth composite responses.