Magneto-Mechanical Metamaterials with Widely Tunable Mechanical Properties and Acoustic Bandgaps

TL;DR

This paper introduces a magneto-mechanical metamaterial with highly tunable mechanical and acoustic properties, achieved through deformation mode branching enabled by asymmetric joint design and magnetic actuation.

Contribution

It presents a novel metamaterial architecture that allows extensive post-fabrication tunability via magnetic and mechanical stimuli, including deformation mode branching and shape memory effects.

Findings

Enables two distinct actuation modes: bending and folding.

Achieves significant tunability in mechanical stiffness and acoustic bandgaps.

Incorporates magnetic shape memory polymers for global stiffness control.

Abstract

Mechanical metamaterials are architected manmade materials that allow for unique behaviors not observed in nature, making them promising candidates for a wide range of applications. Existing metamaterials lack tunability as their properties can only be changed to a limited extent after the fabrication. In this paper, we present a new magneto-mechanical metamaterial that allows great tunability through a novel concept of deformation mode branching. The architecture of this new metamaterial employs an asymmetric joint design using hard-magnetic soft active materials that permits two distinct actuation modes (bending and folding) under opposite-direction magnetic fields. The subsequent application of mechanical forces leads to the deformation mode branching where the metamaterial architecture transforms into two distinctly different shapes, which exhibit very different deformations and enable great tunability in properties such as mechanical stiffness and acoustic bandgaps. Furthermore, this metamaterial design can be incorporated with magnetic shape memory polymers with global stiffness tunability, which further enables the global shift of the acoustic behaviors. The combination of magnetic and mechanical actuations, as well as shape memory effects, imbue unmatched tunable properties to a new paradigm of metamaterials.