Wrinkles Riding Waves in Soft Layered Materials

The formation of periodic wrinkles in soft layered materials due to mechanical instabilities is prevalent in nature and has been proposed for use in multiple applications. However, such phenomena have been explored predominantly in quasi-static settings. Here, the dynamics of soft elastomeric blocks with stiff surface films subjected to high-speed impact are measured, and wrinkles forming along with, and riding upon, waves propagating through the system are observed. The measurements are analyzed with large-deformation, nonlinear visco-hyperelastic finite element simulations coupled to an analytical wrinkling model. The comparison between the measured and simulated dynamics shows good agreement, and suggests that inertia and viscoelasticity play an important role. Here, future studies of the dynamics of surface instabilities in soft materials are encouraged, including cases involving large-deformation, highly nonlinear morphologies. Improved understanding of dynamic wrinkle formation may have applications to areas including impact mitigation, soft electronics, and the dynamics of soft sandwich composites.