Magnetorheological elastomer explained

Magnetorheological elastomers (MREs) (also called magnetosensitive elastomers) are a class of solids that consist of polymeric matrix with embedded micro- or nano-sized ferromagnetic particles such as carbonyl iron. As a result of this composite microstructure, the mechanical properties of these materials can be controlled by the application of magnetic field.^[1]

Fabrication

MREs are typically prepared by curing process for polymers. The polymeric material (e.g. silicone rubber) in its liquid state is mixed with iron powder and several other additives to enhance their mechanical properties.^[2] The entire mixture is then cured at high temperature. Curing in the presence of a magnetic field causes the iron particles to arrange in chain like structures resulting in an anisotropic material. If magnetic field is not applied, then iron-particles are randomly distributed in the solid resulting in an isotropic material. Recently, in 2017, an advanced technology, 3D printing has also been used to configure the magnetic particles inside the polymer matrix. ^[3]

Notes and References

1. Magnetorheology, Editor: Norman M Wereley, Royal Society of Chemistry, Cambridge 2014, https://pubs.rsc.org/en/content/ebook/978-1-84973-754-8
2. Jolly, M. R., Carlson, J. D. & Muñoz, B. C. A model of the behaviour of magnetorheological materials. Smart Mater. Struct. 5, 607–614 (1996).
3. Kankanala, S. V. & Triantafyllidis, N. On finitely strained magnetorheological elastomers. J. Mech. Phys. Solids 52, 2869–2908 (2004).
4. Dorfmann, A. & Ogden, R. W. Magnetoelastic modelling of elastomers. Eur. J. Mech. - A/Solids 22, 497–507 (2003).
5. Song . Hyeonseo . Lee . Hajun . Lee . Jaebyeong . Choe . Jun Kyu . Lee . Suwoo . Yi . Jee Yoon . Park . Sunghoon . Yoo . Jung-Woo . Kwon . Min Sang . Kim . Jiyun . Reprogrammable Ferromagnetic Domains for Reconfigurable Soft Magnetic Actuators . Nano Letters . 3 June 2020 . 20 . 7 . 5185–5192 . 1530-6984 . 1530-6992 . 10.1021/acs.nanolett.0c01418 . 32491865 . 2020NanoL..20.5185S . 219319700 .
6. Kaya . Kerem . Iseri . Emre . van der Wijngaart . Wouter . Soft metamaterial with programmable ferromagnetism . Microsystems & Nanoengineering . 6 December 2022 . 8 . 1 . 127 . 2055-7434 . 10.1038/s41378-022-00463-2 . 36483621. 9722694 . 2022MicNa...8..127K .
7. Deng . Heng . Sattari . Kianoosh . Xie . Yunchao . Liao . Ping . Yan . Zheng . Lin . Jian . Laser reprogramming magnetic anisotropy in soft composites for reconfigurable 3D shaping . Nature Communications . 10 December 2020 . 11 . 1 . 6325 . 2041-1723 . 10.1038/s41467-020-20229-6 . 33303761 . 7730436 . 2020NatCo..11.6325D .
8. Behrooz, M., Wang, X. & Gordaninejad, F. Performance of a new magnetorheological elastomer isolation system. Smart Mater. Struct. 23, 045014 (2014) [link<nowiki>]].

   Further reading

   • Web site: Mathematical modelling of non-linear magneto- and electro-active rubber-like materials.
   • Web site: The Elastic and Damping Properties of Magnetorheological Elastomers. 15 January 2024 .
   • Web site: Theory and Numerical Aspects of Constitutive Modeling in Finite Deformation Magnetomechanics.
   • Web site: Huge Magnetostriction of Magnetorheological Composite.

   See also

   • Conductive elastomer
9. Deng, H. X., Gong, X. L. & Wang, L. H. Development of an adaptive tuned vibration absorber with magnetorheological elastomer. Smart Mater. Struct. 15, N111-N116 (2006) [link<nowiki>]].^[8]
10. A.K. Bastola, V.T Hoang, L. Lin. A novel hybrid magnetorheological elastomer developed by 3D printing. Materials and Design 114, 391–397 (2017) [link<nowiki>]].

    Classification

    MREs can be classified according to several parameters like: particles type, matrix, structure and distribution of particles:

    Particles magnetic properties

    • Soft magnetic particles
    • Hard magnetic particles
    • Magnetostrictive particles
    • Magnetic shape-memory particles

    Matrix structure

    • Solid matrix
    • Porous matrix

    Matrix electrical properties

    • Isolating matrix
    • Conductive matrix

    Distribution of particles

    • Isotropic
    • Anisotropic

    Theoretical Studies

    In order to understand magneto-mechanical behaviour of MREs, theoretical studies need to be performed which couple the theories of electromagnetism with mechanics. Such theories are called theories of magneto-mechanics.^{[3] [4]}

    Programmable magnetopolymers

    Magnetopolymers with large remanence are typically formed by combining hard-magnetic particles with a polymer matrix. The orientation of the magnetic particles is typically controlled with an external magnetic field during the polymerization process, and then mechanically fixed after the material is synthesized. Because the Curie temperature of these magnetopolymers exceeds the temperature at which the polymer matrix would break down, they must be degaussed in order to be remagnetized. This means that the functionality of these magnetopolymers is limited and they can only be permanently programmed during manufacturing.

    Programmable magnetopolymers embed athermal ferromagnetic particles in droplets of low melting point materials in polymer matrices.^{[5] [6] [7]} Above the droplet melting point, the particles have rotational freedom. The uniqueness of these composites exists in their easily reprogrammable magnetization profiles. This behaviour follows from the fact that particles (1) are athermal, (2) have Curie temperatures above the droplet melting point, and (3) are fixated in solid droplets while possessing full rotational freedom in molten droplets. This easy reprogramming is a critical characteristic for such materials to be used in a wide range of applications.

    Applications

    MREs have been used for vibration isolation applications since their stiffness changes within a magnetic field ^[8]