Mode Coarsening or Fracture: Energy Transfer Mechanisms in Dynamic Buckling of Rods.

We present results of a hybrid experimental, theoretical, and simulation-based investigation of the postbuckling behavior of thin elastic rods axially impacted by a projectile. We find a new postbuckling mechanism: mode coarsening. Much akin to inverse energy cascade phenomena in other nonlinear dynamic systems, energy is transferred during mode coarsening from higher to lower wave numbers-unless the rod breaks, abruptly dissipating in the course of fracture the rod's strain energy.