The magnetorheological (MR) system's performance depends on the MR fluid's temperature in operation. This study aims to evaluate the temperature effect of MR fluid on performance while the damper is working. Before synthesizing MR fluid, scanning electron microscopy, X-ray diffraction, and particle size analysis verifies for the synthesis of MR fluid in-house. Characterization of the MR fluid at different temperatures and magnetic fields was carried out. The Herschel-Bulkley model is used to analyse the nonlinearity in the fluid by incorporating the temperature effect. The range of critical parameters used to fabricate the MR damper is selected using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) performance score. The temperature of the MR fluid is measured using an embedded thermocouple while the damper is operating at different loading parameters. The results reveal that the fluid temperature rises significantly from atmospheric to 125.39°C with decrease in damping force by 66.32% at higher loading parameters. The theoretical model predicts the increase in temperature similar to that of the experimental values with an average error of 10.24% in the on-state condition. Particle characterization after dynamic testing reveals particle morphology has not changed but the saturation magnetization of the particles reduced by 57% at higher temperatures (127°C). It is observed through thermogravimetric analysis (TGA) that, the life of the fluid is reduced by 0.25%, which is negligible after dynamic testing of the fluid for approximately 85000cycles. Finally, to imitate the temperature effect on the particle, particles were heat-treated at 200°C, 400°C, and 600°C, and through SEM image, it is confirmed that deterioration of the particle starts after 200°C, if the fluid is operated for a prolonged amount of time.

The present study is aimed to evaluate the torque generation capacity of a two plate rotor magnetorheological (MR) brake using in-house prepared MR fluid. The prepared MR fluids were studied for sedimentation rate at different temperatures and flow characterization at different currents and at specific temperatures. The yield stress of the fluid is explored through Herschel-Bulkley (HB) model. The results depict significant increase in sedimentation rate and decrease in yield stress with increase in temperature of the MR fluid. MR brake (model-1) is fabricated after finite element method magnetics (FEMM) exhibit magnetic field of approximately 0.145 T in the shear gap than other two models (model-2 and model-3) considered in this study. Characterization of the MR brake illustrates that there is an increase in torque with increasing current. Further tests have been carried out to identify the effect of sedimentation on torque generation at 52 °C after 15 hours of sedimentation. The results indicate 16 % reduction in the initial torque because of settling of particles. MR fluid and particles characterization illustrates that 322 °C and 400 °C are critical points in controlling the MR fluid input parameters.