Dynamic compression testing of a tunable spring element consisting of a magnetorheological elastomer

Magnetorheological elastomers (MRE) are interesting candidates for active vibration control of structural systems. In this study, spring elements consisting of magnetorheological elastomer were prepared and tested in dynamic compression to study the changes in their stiffness and vibration damping characteristics under the influence of a magnetic field. Aligned and isotropic magnetorheological elastomer composites were prepared using room temperature vulcanizing silicone elastomer as the matrix material and carbonyl iron as the magnetizable filler. Aligned MREs were prepared by curing the material under an external magnetic field. Aligned MREs were tested and the results were compared with isotropic composites with no preferred orientation. The mechanical properties of the MREs were tested in cyclic compression passively and with increasing magnetic flux density. The influence of the testing frequency and strain amplitude on the dynamic stiffness and damping properties was studied. It was noted that when measured in a magnetic field both the dynamic spring constants and the loss factor values of aligned MREs were increased compared to the zero-field values. The dynamic stiffness of aligned MREs increased with increasing testing frequency and it was tunable with magnetic flux density in the studied frequency range. The loss factor of aligned MREs was also tunable with the magnetic flux density but the absolute values also depend on the testing frequency. The dynamic stiffness of the aligned MREs measured in compression decreased with increasing strain amplitude, but the damping properties were not affected similarly. On the basis of these results, MREs are applicable as tunable spring elements for active vibration control.