Experimental investigations and characterization of shear and squeeze mode magnetorheological brake

Owing to their quick response as compared to conventional hydraulic brakes, magnetorheological brakes (MR brakes) are being investigated for a variety of applications. MR brakes usually operate in a shear mode, and thus, lower braking torque is observed to be limiting factor for their adoption for applications like road vehicles. This work presents experimental investigations on shear and squeeze mode MR brake which may potentially offer higher torque as compared to shear mode MR brake. Design of the brakes including the squeeze mechanism is presented which is followed by analytical estimation of output torque for both types of brakes. Experimental investigations in terms of braking torque for various levels of influencing parameters, viz. input current and speed and temperature rise during brake actuation, are carried out with the help of specially designed experimental setup. The analytical and experimental results for both types of MR brakes are compared and discussed. Correlation analysis is made using MINITAB to ascertain the effect of influencing parameters on brake torque output. Though the marginal rise in torque output is observed with squeeze mode MR brake, further design efforts are essential for exploring and realizing squeeze mode MR brake applications.