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

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. Herein, a new magneto-mechanical metamaterial is presented 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 compression 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 also allows for the global shift of the acoustic behaviors. The combination of magnetic and mechanical actuations, as well as shape memory effects, impart wide tunable properties to a new paradigm of metamaterials.

Multifunctional magnetic soft composites: a review

“…The properties and functionalities of the soft material systems are related to the configurations and deformations of the structures. With the ability to undergo large deformations as programmed, the mechanical [ 46 , 80 , 107 , 121 ], optical [ 112 , 122 ], and acoustic properties [ 120 , 123 – 127 ], or wettability [ 106 , 119 ] of magnetic soft composites are actively tunable under the applied magnetic field. For instance, an array of microplates embedded with aligned Fe microparticles possess a superhydrophobic or hydrophilic surface on each side of the plates ( figure 5(d) [ 119 ]).…”

“…As shown in figure 5(e) , by designing structure geometries and magnetization distributions, an auxetic metamaterial shows actively controllable stiffness down to 20% of the initial stiffness under the external magnetic field [ 46 ]. With a considerable area shrinkage, both the number and the magnitude of the acoustic bandgaps can be tuned by tailoring the magnetic field [ 120 ]. Figure 5(f) illustrates an active metamaterial system with the structural integration of magnetic soft materials and magnetic SMPs.…”

“…(e) Auxetic metamaterials with actively tunable stiffness (Left: Adapted with permission from [ 46 ]. Copyright 2019, American Chemical Society) and acoustic bandgaps (Right: Adapted with permission from [ 120 ]. Copyright 2020, Wiley).…”

Oligomodal metamaterials with multifunctional mechanics

“…Our approach is fundamentally different from and is complementary to recent developments based on poroelasticity ( 29 ) and magnetoelasticity ( 30 ). In these works, multifunctionality is achieved through elaborate actuation multiphysics couplings and via loading in the bulk: The loading is exerted on the bulk by external fields, such as a chemical potential or a magnetic field.…”

Rapidly deployable and morphable 3D mesostructures with applications in multimodal biomedical devices

“…Miniaturizing such structures to be comparable to the small scale in natural and/or human-engineered living systems such as arteries (1∼10 mm) (3), early-stage lesions (4), and organoids (∼1 mm) (5), and in minimally invasive surgeries (4) could broaden their applications in biomedical, healthcare, and electronic devices (6,7). Recent advances in manufacture, fabrication, and assembly techniques enable the use of materials that respond to irradiation (8)(9)(10)(11)(12), magnetic field (13)(14)(15)(16)(17)(18)(19)(20)(21), electric field (22)(23)(24)(25)(26)(27), electromagnetic field (28,29), heat (17,(30)(31)(32)(33)(34)(35)(36), chemicals (37,38), and pressures (39,40) to remotely actuate large structural deformations (41)(42)(43)(44)(45)(46)(47). For example, the three-dimensional (3D) printing technique of programmed ferromagnetic domains developed by Kim et al…”