  Dynamic buckling may occur when a load is rapidly applied to, or removed
from, an elastic object at rest. In contrast to its static counterpart, dynamic
buckling offers a wide range of accessible patterns depending on the parameters
of the system and the dynamics of the load. To study these effects, we consider
experimentally the dynamics of an elastic ring in a soap film when part of the
film is suddenly removed. The resulting change in tension applied to the ring
creates a range of interesting patterns that cannot be easily accessed in
static experiments. Depending on the aspect ratio of the ring's cross section,
high-mode buckling patterns are found in the plane of the remaining soap film
or out of the plane. Paradoxically, while inertia is required to observe these
non-trivial modes, the selected pattern does not depend on inertia itself. The
evolution of this pattern beyond the initial instability is studied
experimentally and explained through theoretical arguments linking dynamics to
pattern selection and mode growth. We also explore the influence of dynamic
loading and show numerically that by imposing a rate of loading that competes
with the growth rate of instability, the observed pattern can be selected and
controlled.
