Magneto-mechanical properties of sintered NdFeB under impact load: Impact-induced demagnetization experiment, constitutive model and micromagnetic simulation

Abstract

With the widespread applications of sintered NdFeB, the impact-prone scenarios are often encountered. Such impacts will cause magnetic disorder inside the magnet and further demagnetization. At present, research on impact-induced demagnetization of sintered NdFeB mostly focuses on experimental investigations, lacking clear theoretical expressions and visual reproduction of the microscopic demagnetization process. To end this, this paper uses the impact-induced demagnetization experiment, theoretical expression, and micromagnetic simulation to reveal and quantify the demagnetization behavior of NdFeB. An impact-induced demagnetization experimental platform capable of producing corresponding load amplitudes is first established. The experimental results demonstrate the existence of reversible and irreversible demagnetization of NdFeB under impact. A magneto-mechanical constitutive model for sintered NdFeB considering stress history is further developed using the principle of thermodynamic, pinning effect and proximity effect. The residual magnetization intensity between the numerical simulation and the experimental results have good agreement. Finally, the demagnetization behavior of the magnet is visually displayed through the micromagnetic simulation. Employing the LLG equation and kinematic equations for elastic waves, a set of magnetization dynamics equations is established to analyze impact-induced demagnetization characteristics in sintered NdFeB. These results will provide the reference for the application of NdFeB in impact environment.