Magnetorheological elastomers (MREs) are composite materials made of magnetizable particles embedded in a soft elastomeric matrix. They belong to the class of smart or active materials since some of their properties, in particular their stiffness, can be modified by the application of an external stimulus, a magnetic field in their case. In the presence of a magnetic field, they can also exhibit large deformations and/or displacements. Hence, they stand as promising candidates for a number of engineering applications linked to tunable damping, non-contact actuation, morphing surfaces or artificial muscles. The simplest form of MRE samples is isotropic due to a homogeneous dispersion
of magnetizable spherical particles in their matrix but curing these composites under magnetic fields can impart them with anisotropic properties through the creation of particle chains in the direction of the curing field. In this work, the coupled magneto-mechanical behavior of both isotropic and anisotropic soft MREs is characterized experimentally with a dedicated setup, thus revealing that structural instabilities are ubiquitous in all samples [1]. Such instabilities are further harnessed in model structures comprising
MRE thin films [2,3]. In particular, a structure made of an MRE thin film deposited on a soft non-magnetic substrate provides a device that can display reversible wrinkles at its surface under coupled magneto-mechanical loading [3]. The influence of the magneto-mechanical loading parameters on the morphology of the obtained wrinkles [4] is analyzed and the prospect for transitioning from 2.5D patterns to 3D patterns will be discussed.
References
[1] Bodelot, L., Voropaieff, J.-P., Pö ssinger, T., “Experimental investigation of the coupled
magneto-mechanical response in magnetorheological elastomers”, Experimental Mechanics, 58, 207–221 (2018). DOI: 10.1007/ s11340-017-0334-7
[2] Psarra, E., Bodelot, L., Danas, K., “Two-field surface pattern control via marginally stable magnetorheological elastomers”, Soft Matter, 13, 6576–6584 (2017). DOI:
10.1039/C7SM00996H
[3] Psarra, E., Bodelot, L., Danas, K., “Wrinkling to crinkling transitions and curvature
localization in a magnetoelastic film bonded to a non-magnetic substrate”, Journal of the
Mechanics and Physics of Solids, 133, 103734 (2019). DOI: 10.1016/j.jmps.2019.103734
[4] Dorn, C., Bodelot, L., Danas, K, “Experiments and Numerical Implementation of a Boundary Value Problem Involving a Magnetorheological Elastomer Layer Subjected to a Nonuniform Magnetic Field”, Journal of Applied Mechanics, 88, 071004 (2021). DOI: 10.1115/1.4050534