# Dynamic buckling of elastic rings in a soap film

## TL;DR

This paper investigates the dynamic buckling behavior of elastic rings in soap films when subjected to sudden tension changes, revealing pattern formation influenced by load rate and geometry, with experimental and theoretical insights.

## Contribution

It introduces a novel experimental setup to study dynamic buckling patterns in elastic rings within soap films and links pattern selection to load rate and system parameters.

## Key findings

- High-mode buckling patterns depend on aspect ratio and loading dynamics.
- Pattern selection can be controlled by adjusting the rate of load application.
- Inertia influences pattern emergence but not the pattern type itself.

## Abstract

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.