Experimental Study and Numerical Simulation of Demagnetization Behavior of Sintered NdFeB Used in Eddy Current Brake

Abstract

Aiming at the problems of liquid leakage and difficult maintenance of hydraulic brake on traditional artillery,the eddy current brake using electromagnetic damping theory emerges as the times require. Sintered NdFeB is the key functional part of eddy current brake,and its magnetic field retention problem in the artillery launch environment has attracted much attention. To study this issue,a shock loading demagnetization experiment-platform was established,and the shock demagnetization experiments were conducted. The impact load and induced electromotive force of the magnet at different speeds were measured,and the magnetic flux curve of the magnet was obtained. Combined with the characteristics of experimental data, a theoretical model of shock loading demagnetization of sintered NdFeB was established. The co-simulation model of the shock demagnetization process was established. The validity of the theoretical model of shock demagnetization was verified by comparing with the experimental values. The non-linear dynamic model of the artillery launch was established. Combined with the established shock demagnetization model,the demagnetization effect of the eddy current brake of the artillery was studied. The results show that, the rightmost sintered NdFeB permanent magnet is in the reversible demagnetization region,and an irreversible demagnetization phenomenon occurs in the inner ring of the permanent magnet,and the demagnetization amount is 0.275 T. The material properties of sintered NdFeB are expanded. The simulation of the demagnetization effect in the eddy current brake provides the theoretical basis and reference for the engineering of sintered NdFeB in the eddy current brake.