Magneto-active elastic shells with tunable buckling strength

TL;DR

This paper introduces a method to dynamically control the buckling strength of elastic shells using magnetic actuation, combining experiments and theory to understand the magneto-elastic coupling.

Contribution

It presents a novel mechanism for tuning shell buckling pressure through magnetic coupling, supported by experimental validation and a theoretical model.

Findings

Magnetic actuation can significantly alter shell buckling pressure.

A dimensionless magneto-elastic buckling number governs the system behavior.

The theoretical model aligns well with experimental results.

Abstract

Shell buckling is central in many biological structures and advanced functional materials, even if, traditionally, this elastic instability has been regarded as a catastrophic phenomenon to be avoided for engineering structures. Either way, predicting critical buckling conditions remains a long-standing challenge. The subcritical nature of shell buckling imparts extreme sensitivity to material and geometric imperfections. Consequently, measured critical loads are inevitably lower than classic theoretical predictions. Here, we present a robust mechanism to dynamically tune the buckling strength of shells, exploiting the coupling between mechanics and magnetism. Our experiments on pressurized spherical shells made of a magnetorheological elastomer demonstrate the tunability of their buckling pressure via magnetic actuation. We develop a theoretical model for thin magnetic elastic shells, which rationalizes the underlying mechanism, in excellent agreement with experiments. A dimensionless magneto-elastic buckling number is recognized as the key governing parameter, combining the geometrical, mechanical, and magnetic properties of the system.