A method to approach constant isotropic permeabilities and demagnetization factors of magneto-rheological elastomers

Chavez, Jhohan; Ziółkowski, Marek; Schorr, Philipp; Spieß, Lothar; Böhm, Valter; Zimmermann, Klaus

doi:10.1016/j.jmmm.2021.167742

Cited by 2 publications

(1 citation statement)

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“…Such magneto-sensitive materials are usually composed of two phases: i) a continuous or carrier phase and ii) a discontinuous or dispersed phase embedded in the former. Regarding the carrier matrix, they are usually classified as magnetorheological fluids [3,15,69], ferrogels [23,84] and magnetorheological elastomers [6,5,17,28,32,49]. Magnetorheological elastomers (MREs) are composed of a vulcanized polymeric carrier matrix with magnetic particles embedded on fixed positions.…”

Section: Introductionmentioning

confidence: 99%

Effects of soft and hard magnetic particles on the mechanical performance of ultra-soft magnetorheological elastomers

Moreno-Mateos

López-Donaire

Hossain

et al. 2022

Smart Mater. Struct.

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Magnetorheological elastomers (MREs) mechanically respond to external magnetic stimuli by changing their mechanical properties and/or changing their shape. Recent studies have shown the great potential of MREs when manufactured with an extremely soft matrix and soft-magnetic particles. Under the application of an external magnetic field, such MREs present significant mechanical stiffening, and when the magnetic field is off, they show a softer response, being these alternative states fully reversible. Although soft-magnetic particles are suitable for their high magnetic susceptibility, they require the magnetic actuation to remain constant in order to achieve the magneto-mechanical stiffening. Here, we present an alternative solution based on hard-magnetic MREs to provide stiffening responses that can be sustained along time without the need of keeping the external magnetic field on. To this end, we manufacture novel extremely soft hard-magnetic MREs (stiffness in the order of 1~kPa) and characterise them under magneto-mechanical shear and confined magnetic expansion deformation modes, providing a comparison framework with the soft-magnetic counterparts. The extremely soft nature of the matrix allows for easily activating the magneto-mechanical couplings under external magnetic actuation. In this regard, we provide a novel approach by setting the magnetic actuation below the fully magnetic saturating field. In addition, free deformation tests provide hints on the microstructural transmission of torques from the hard-magnetic particles to the viscoelastic carrier matrix, resulting in macroscopic geometrical effects and complex functional morphological changes.

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