Mechanical and magnetic responses of sintered NdFeB under impact

Sintered neodymium iron boron (NdFeB) has been widely applied in various industrial fields thanks to its excellent magnetic properties. However, the impact loads in increasing number of applications challenged its mechanical safety and magnetic field reliability. This is a blind spot in the existing researches on the properties of sintered NdFeB. To tackle this, this article proposes a dynamic damage constitutive model and impact demagnetization model respectively to illustrate the dynamic mechanics and impact demagnetization process of sintered NdFeB. Specifically, Split Hopkinson Pressure Bar (SHPB) experiments are conducted to obtain the dynamic response of sintered NdFeB at different strain rates. The dynamic fracture process of NdFeB is also analyzed by combining the damage constitutive model based on experimental data with the SHPB dynamic simulation model. This is the foundation of the demagnetization model in subsequent. Different from the previous researches on complete demagnetization caused by intensive impacts at the magnitude of GPa, the demagnetization study in this article is aimed at the more regular impacts below 100 MPa. Based on the stress knee hypothesis and irreversible aggravation hypothesis respectively, the reversible and irreversible processes during the demagnetization are individually demonstrated in the form of magnetic domain flip. The specific comparison between simulation and experimental results verified the effectiveness of the demagnetization model.