From Newton's Cradle to New Materials
The bouncing beads of Newton's cradle fascinate children and executives alike, but their symmetric dance hides complex nonlinear dynamic behavior. Lift a bead on one side off a chain of a few suspended beads, let it swing back: one bead bounces off on the other side. Do the same with a long chain of beads: several beads bounce off on the other side. This represents an example of nonlinear wave dynamics, which can be exploited for a variety of engineering applications.By assembling grains in crystals or layers in composites such that they support nonlinear waves, we are developing new materials and devices with unique properties. We have constructed acoustic lenses that allow sound to travel as compact bullets that can be used in medical applications, have developed new materials for absorbing explosive blasts, and are exploring new ways to test aircraft wings and bone implants nondestructively with the help of nonlinear waves.
Chiara Daraio, California Institute of Technology, USA