Experimental Studies on Magnetorheological Brake for Automotive Application

Automotive brake performance in terms of stopping time largely influences the occupant and pedestrian safety. Conventional hydraulic brakes are being used despite the delayed time response of around 200 ms. This work envisages magneto-rheological (MR) brake, as an automotive service brake owing to its response time of about 15-20 ms. The work proposes design of shear mode MR brake for the automotive application under consideration. Preliminary magnetostatic analysis is done to estimate the output torque of MR brake. It is followed by experimental evaluation of the MR brake prototype in terms of output torque and temperature rise. Details of experimental set up and the test procedure are presented. Variation of output torque with input current and speed is recorded along with results of thermal evaluation. Finally, correlation analysis is used to ascertain the effect of influencing parameters viz. current and speed on output torque of MR brake. Regression equation is obtained to relate the torque output with input parameters. Though the influence of input parameters is characterized, the study underlines the need for high yield stress MR fluids or breakthrough design approach in order for MR brake to be considered for automotive application.