Comparative study on the performance of an optimized T-shaped magnetorheological brake with unimodal, bimodal and commercial MR fluid

The rheological properties of Magneto-Rheological Fluid (MRF) changes under the influence of magnetic field. Utilizing this field-response behaviour, MRF are widely used in the development of semi-active devices for various engineering applications. Present study focuses on preparation of unimodal and bimodal MRF with solid weight fraction similar to that of commercial MRF (Make: Lord Corporation MRF 132DG) and characterized at room and elevated temperatures to analyse effect of temperature on rheological properties. Further, T-shaped MR brake was optimized through magnetostatic analysis, considering the properties of commercial MRF, with maximizing the braking torque and dynamic ratio using MATLAB software. The optimized T-shaped MR brake was fabricated and characterized under varying coil currents and rotational speeds considering unimodal, bimodal and commercial MRF. From characterization results, unimodal MRF generated the maximum braking torque of 33.24 Nm at 3 A, outperforming bimodal and commercial MRF. In addition, an attempt was made to measure the MRF temperature at various locations within the brake through thermocouples for all characterization cases. Through this temperature study, it is evident that maximum MRF temperature was observed near the shaft region, while temperature drop was observed at MRF in outer T-flange region and minimum at outer casing of the brake.