Tunable magneto-granular phononic crystals

TL;DR

This study explores 1D magneto-granular phononic crystals, demonstrating tunable band gaps and transverse-rotational wave modes through magnetic field adjustments, highlighting their potential as nonlinear, tunable elastic wave control metamaterials.

Contribution

It introduces a novel magneto-granular phononic crystal system with tunable band gaps and includes experimental validation of transverse-rotational modes.

Findings

Magnetic field strength tunes the dynamic response.

Experimental evidence of transverse-rotational wave modes.

Potential for nonlinear, tunable wave control applications.

Abstract

This paper reports on the study of the dynamics of 1D magneto-granular phononic crystals composed of a chain of spherical steel beads inside a properly designed magnetic field. This field is induced by an array of permanent magnets, located in a holder at a given distance from the chain. The theoretical and experimental results of the band gap structure are displayed, including all six degrees of freedom for the beads, i.e. three translations and three rotations. Experimental evidence of transverse-rotational modes of propagation is pre- sented; moreover, by changing the strength of the magnetic field, the dynamic response of the granular chain is tuned. The combination of non-contact tunability with the potentially strong nonlinear behavior of gran- ular systems ensures the suitability of magneto-granular phononic crystals as nonlinear, tunable mechanical metamaterials for use in controlling elastic wave propagation.