Smart metamaterials with tunable auxetic and other properties

Grima, Joseph N.; Caruana‐Gauci, Roberto; Dudek, Mirosław R.; Wojciechowski, Krzysztof W.; Gatt, Ruben

doi:10.1088/0964-1726/22/8/084016

Cited by 138 publications

(105 citation statements)

References 30 publications

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“…It is also generalized for arbitrarily complex elastic structures, but is not presented for use in systems exhibiting non-nearest neighbor interactions, such as magnetic interactions, and must therefore be extended for application to magneto-elastic lattices. In contrast to the work by Grima et al [13], the structures discussed in this publication contain magnetic dipole moments perpendicular to the lattice plane, and mechanical properties including stiffnesses are presented. The changes Poisson's ratio in this publication are not brought about solely by geometric orientation as in reference [13], but also through changes in interaction stiffnesses, which are caused by the included magnets.…”

Section: Introductionmentioning

confidence: 90%

“…In contrast to the work by Grima et al [13], the structures discussed in this publication contain magnetic dipole moments perpendicular to the lattice plane, and mechanical properties including stiffnesses are presented. The changes Poisson's ratio in this publication are not brought about solely by geometric orientation as in reference [13], but also through changes in interaction stiffnesses, which are caused by the included magnets. Furthermore, this publication focus specifically on the multistability and bistability of the studied lattices and how reconfiguration effects properties.…”

Section: Introductionmentioning

confidence: 90%

“…Related work has been presented [13] in which finite magneto-elastic structures show that their Poisson's ratio can be tuned with the application of a non-uniform external magnetic field and through changes in constituent dimensions. The magnetic dipole moments in the 2D structures discussed therein are oriented in the plane of the system and the changes in Poisson's ratio are a result of the re-orientation of the system's rigid entities under the constant application of the external magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Homogenization of 1D and 2D magnetoelastic lattices

Schaeffer

Ruzzene

2015

EPJ Applied Metamaterials

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-This paper investigates the equivalent in-plane mechanical properties of one dimensional (1D) and two dimensional (2D), periodic magneto-elastic lattices. A lumped parameter model describes the lattices using magnetic dipole moments in combination with axial and torsional springs. The homogenization procedure is applied to systems linearized about stable configurations, which are identified by minimizing potential energy. Simple algebraic expressions are derived for the properties of 1D structures. Results for 1D lattices show that a variety of stiffness changes are possible through reconfiguration, and that magnetization can either stiffen or soften a structure. Results for 2D hexagonal and re-entrant lattices show that both reconfigurations and magnetization have drastic effects on the mechanical properties of lattice structures. Lattices can be stiffened or softened and the Poisson's ratio can be tuned. Furthermore for certain hexagonal lattices the sign of Poisson's ratio can change by varying the lattice magnetization. In some cases presented, analytical and numerically estimated equivalent properties are validated through numerical simulations that also illustrate the unique characteristics of the investigated configurations.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Homogenization of 1D and 2D magnetoelastic lattices

Schaeffer

Ruzzene

2015

EPJ Applied Metamaterials

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“…Mater. 2016, 28, 5176-5180 www.advmat.de www.MaterialsViews.com Micro-and nano-auxetic metamaterials combined with actuation mechanisms of reconfi gurable terahertz and photo nic metamaterials [ 30,31,33,34 ] promise a class of tunable nano mechanical metadevices with fi xed optical anisotropy. In contrast to conventional materials and metamaterials, where stretching or compression necessarily changes the anisotropy of the structure, auxetics provide an opportunity where both the aspect ratio of the unit cell and its corresponding optical anisotropy (or isotropy) can in principle remain unchanged with actuation.…”

Section: Doi: 101002/adma201600088mentioning

confidence: 99%

Nano‐ and Micro‐Auxetic Plasmonic Materials

et al. 2016

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and epoxy-resin casting.[ 19 ] Soft lithography, [ 12 ] femtosecond laser ablation, [ 13 ] and digital micromirror device projection printing [ 14 ] have allowed the fabrication of negative Poisson's ratio structures with characteristic sizes of hundreds of micrometers. Smaller dielectric auxetics with unit cells on the order of 100 µm have been made by laser micromachining, [ 15 ] while dielectric auxetics with a characteristic size of 10 µm have been realized by direct laser writing. [ 16 ] However, negative Poisson's ratio materials with nanoscale lattice para meters cannot be fabricated using such techniques due to their limited resolution and the complexity of auxetic designs. Nevertheless, nanoscale auxetics would be particularly interesting as optical materials, considering that the combination of transformation optics concepts [ 20 ] with dielectric properties of auxetic meta materials [ 19,[21][22][23][24][25] already promises better electromagnetic cloaking devices for microwaves. [ 26,27 ] Here, we realize micro-and nanoscale metamaterial structures and demonstrate negative Poisson's ratios by mechanical actuation ( Figure 1 ). Our nano-auxetic metamaterials are based on the re-entrant honeycomb design, which is known for auxetic properties for a wide range of beam thicknesses, sizes, and angles. [ 11 ] Inspired by recent work in the fi eld of nanomechanical photonic devices, [ 28 ] nanomembrane technology was used to fabricate auxetics with lattice parameters in the range from a few micrometers to hundreds of nanometers. Nanomembrane technology has already provided simple and effi cient solutions for reconfi guration of nanoscale structures that are not auxetic, enabling nanomechanical devices and sensors. In particular, engineered resonant optical properties and anisotropic light modulation with up to 50% optical contrast has been demonstrated with reconfi gurable metamaterials actuated by thermal, [ 29 ] electric, [ 30 ] and magnetic [ 31 ] signals, and fabricated from plasmonic-thin-fi lm-coated nanomembranes.The auxetic materials are shown by Figure 2 and were fabricated by thermally evaporating a 60 nm-thick gold plasmonic layer on a commercially available silicon nitride membrane of 50 nm thickness and then milling the re-entrant honeycomb structure through both layers using a gallium-focused ion-beam system (Helios 600 NanoLab by FEI). All structures were milled with an ion-beam energy of 30 keV. Infrared auxetic metamaterial microstructures were fabricated with 70 pA ion-beam current and a spot size of 21 nm, while nano-auxetic structures were milled with a reduced ion current of 9 pA and a smaller spot size of 12 nm. The honeycomb pattern has a rhombic unit cell and wallpaper symmetry group cmm . [ 32 ] For simplicity, we specify the smallest rectangular cell, p x × p y , that describes each structure, where the periodicities p x and p y along x and y correspond to the diagonals of the elementary rhombic unit cell, see Auxetics, materials with a negative Poisson's ratio, are rare in nature. ...

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“…The first papers on auxetic materials and structures appeared more than 20 years ago [5,[7][8][9][10] however only recently were they studied for their magnetic properties. Such studies include investigations on the magnetic properties of auxetic foams [11,12], magnetic ferrogels [13,14], CoFe 2 O 4 epitaxial thin films [15], magnetostrictive iron-gallium alloys galfenol [16] and MASs [17]. Wave propagation was also investigated in magneto-elastic lattices [18].…”

Section: Introductionmentioning

confidence: 99%

Colossal magnetocaloric effect in magneto-auxetic systems

Dudek

Wojciechowski

Grima

et al. 2015

Smart Mater. Struct.

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We show that a mechanically driven magnetocaloric effect (MCE) in magneto-auxetic systems (MASs) in the vicinity of room temperature is possible and the effect can be colossal. Even at zero external magnetic field, the magnetic entropy change in this reversible process can be a few times larger in magnitude than in the case of the giant MCE discovered by Pecharsky and Gschneidner in Gd 5 (Si 2 Ge 2 ). MAS represent a novel class of metamaterials having magnetic insertions embedded within a non-magnetic matrix which exhibits a negative Poisson's ratio. The auxetic behaviour of the non-magnetic matrix may either enhance the magnetic ordering process or it may result in a transition to the disordered phase. In the MAS under consideration, a spin 1/2 system is chosen for the magnetic component and the well-known Onsager solution for the two-dimensional square lattice Ising model at zero external magnetic field is used to show that the isothermal change in magnetic entropy accompanying the auxetic behaviour can take a large value at room temperature. The practical importance of our findings is that MCE materials used in present engineering applications may be further enhanced by changing their geometry such that they exhibit auxetic behaviour.

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Smart metamaterials with tunable auxetic and other properties

Cited by 138 publications

References 30 publications

Homogenization of 1D and 2D magnetoelastic lattices

Homogenization of 1D and 2D magnetoelastic lattices

Nano‐ and Micro‐Auxetic Plasmonic Materials

Colossal magnetocaloric effect in magneto-auxetic systems

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