Magnetostrictive effect of magnetorheological elastomer

Magnetorheological elastomer (MRE) has been known for its magnetic field-dependent stiffness, but only a few works study its magnetostrictive property. The aim of this paper is to present results of studies on magnetostriction of the MRE consisting of carbonyl iron particles displaced in the matrix made of a silicone rubber. The MRE samples were placed in the magnetic field that varied from 0 to 636 kA/ m, which was produced by the PEM-1022LS magnetic system. The longitudinal magnetostriction of the samples was measured by strain gauge. Three different tests were performed: ( 1) increased and decreased magnetic fields on four different volume fraction MREs with particles randomly dispersed, namely, 0%, 15%, 20% and 27%, ( 2) increased and decreased magnetic fields on three different MREs, with the same volume fraction of particles but varied orientation, namely, randomly, vertically and parallelly; ( 3) increased and decreased magnetic field three times continuously on the MRE with particles randomly oriented. Results indicated that ( 1) magnetostrictive effect increases with increase in volume fraction of particles and magnetostriction generally increases with increasing magnetic field, ( 2) orientation of particles influences the magnetostrictive performance significantly, ( 3) with increase of times of tests, saturation strain decayed and some remnant magnetostriction existed after switching off the magnetic field in each cycle. The mechanism of magnetostrictive effect of the composite was proposed to explain the phenomenon. (C) 2007 Published by Elsevier B.V.