Design of MRF Brake for Dual-Spin Artillery Projectile

This article presents the electromagnetic-thermal design and optimization of an Aluminum Ring Embedded Cylindrical (AREC) Magnetorheological Fluid (MRF) brake for high-speed, high-torque applications, particularly in the Fixed Canard Decoupled Dual-Spin Artillery Projectile (FCD-DSAP) system. An analytical model based on the magnetic equivalent circuit (MEC) method is developed to estimate the fluid gap magnetic field intensity. The Bingham fluid model is used to characterize the MRF-132DG fluid in its linear region, enabling an accurate evaluation of the braking torque. The brake is optimized by considering the total length of the brake, the excitation current, and the number of coil turns as decision variables. The optimized model is implemented in ANSYS Maxwell and the Bingham fluid model to obtain correlated speed, current, and torque data. These data are integrated into the dual-spin artillery projectile dynamic equation, where a zero angular-speed control for the canard is implemented using a PI controller, allowing for the estimation of net frictional power loss throughout the flight regime. The power loss data, combined with thermal boundary conditions, are then used in ANSYS transient thermal analysis to assess the thermal performance of the brake. The results confirm that the fluid temperature remains within the specified limits, ensuring the reliability and effectiveness of the brake in the underlying applications.