Magnetorheological (MR) gels belong to a group of smart materials whose attributes can be altered when it is exposed to an external magnetic field. The mechanical response of MR gels arises from the contribution of magnetic particles and the polymer matrix while the magnetic response arises from the interaction between the magnetic particles and the applied external field. Here, the investigation on the creep behavior of MR gels under constant stress is taken up to design and optimize the CI particulate MR gels. MR gels are prepared by dispersing carbonyl iron (CI) microparticles of different volume percentages (10 %, 20 % and 30 %) in a polymer gel. Further, the effect of the magnetic field, constant stress level, and volume percentage of filler particles on the creep behavior of MR gels has been investigated using a simple free decay apparatus built in-house. From the results, a clear increasing trend is noticed in the creep resistance of the magnetic gel with the increase in the volume percentage of the particles under the same magnitudes of the magnetic field. The obtained experimental creep data are fitted suitably using a three-parameter model.
In continuation to the creep study, a microstructure based approach is adopted to develop a model to study the influence of the size of the magnetic particles on the magneto-mechanical behavior of the MR gels. The model is calibrated and validated using a set of experimental data. The results indicate an increasing trend in the modulus value as the particle size decreases under the same volume fraction and magnetic field conditions.