**3.1 Preparation of MR fluids**

The nano sized iron particles (Fe3O4) of size 10–12 nm were used as a smart material and silicone oil as the carrier oil. The MR fluid was prepared by mixing 80% of weight of silicone oil and with 20% Fe3O4 particles. The addition of Fe3O4 was slow and uniform under stirring condition for about 30 minutes. Then, the above mixture is sonicated about 1 hour under the frequency of 0.5 Hz. During sonication, the major proportion dispersed with the silicon oil. Therefore, there discourages the gravity settling. The off-state viscosity of the MR fluid prepared at 270 c is 0.822 Pa-s. **Figure 4** depicts the schematic representation for the preparation of MR fluid.
