Development and evaluation of a novel multiple variable working gap magnetorheological brake

Abstract Magnetorheological (MR) brakes utilize the field-induced shear yield stress characteristics of MR fluids to provide controllable and reversible torque regulation for advanced braking systems. Although current designs show promise in automotive and autonomous driving applications, their performance is limited by the use of fixed working gaps. These fixed gaps cannot simultaneously meet the conflicting demands of increased torque output, a wider regulation range, reduced shear‐induced heat generation, and lower no‐load losses. To overcome these limitations, this study proposes a novel multi-disc MR brake featuring a wedge-shaped split brake-disc configuration that enables continuous adjustment of multiple working gaps in the range of 0.25–0.75 mm. A torque model was first established based on the Bingham model, and subsequent multi-condition electromagnetic field simulations were conducted to investigate the magnetic flux distribution under varying currents and gap configurations. A dedicated test platform was constructed for experimental evaluation of the braking performance. The proposed brake achieves a wide dynamic range of 46.17 dB, significantly expanding the controllable torque envelope. Results demonstrate that gap variation significantly influences zero-field torque and exhibits higher sensitivity than speed modulation, while speed adjustment exerts a greater impact on overall torque output. A mean deviation of 7.2% between simulation and experimental data validates the torque model. Under magnetic excitation, braking torque exhibits nonlinear current-dependent growth with distinct threshold effects and interactive coupling characteristics across different gaps. Dynamic response tests reveal that gap adjustment reduces braking response time by approximately 12.3%. Long-term static experiments elucidate non-monotonic torque decay patterns caused by MR fluid sedimentation under different excitation currents.