Investigation on variable shear modulus of magnetorheological elastomer based on natural rubber due to change of fabrication design



A magnetorheological elastomer (MRE) is a smart material that has a reversible and variable modulus in a magnetic field. Natural rubber (NR), which has better mechanical properties than other rubbers, was used as the matrix. Carbonyl iron powder (CIP) was selected for the generation of a magnetic field-dependent modulus in the MREs. The MRE specimens were cured in an anisotropic mold, which was used to induce a magnetic field. SEM images validated the CIP orientation. The shear modulus of the MREs was evaluated under a magnetic field induced by a magnetic flux generator (MFG). An evaluation system was designed that includes an MFG, which is a device that generates a magnetic field via a continuously variable-induced current to determine the magnetic field-dependent shear modulus. The variations of the shear modulus were observed with increasing CIP volume fraction and induced current. The experimental results revealed that the maximum variation rate of the shear modulus was 76.3% for 40 vol% of CIP and an induced current of 4 A. Using these results, the appropriate CIP volume fraction and induced current can be proposed as the guidelines in fabrication design of MREs based on NR. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers