Experimental and theoretical model study on the dynamic mechanical behavior of sintered NdFeB

Abstract

Sintered neodymium iron boron (NdFeB) is a widely applied permanent magnet, whose dynamic mechanical properties restrict the further development of its application. In order to provide a theoretical basis for the application of NdFeB in the shock field, the dynamic mechanical behavior of sintered NdFeB was studied experimentally and theoretically in this paper. First, the Split Hopkinson Pressure Bar (SHPB) experiments under different strain rates were carried out. The dynamic process was captured by a high-speed camera, and the strain data measured by oscilloscope was processed with the three-wave method. Combined with the electron microscope analysis of the recovered samples, the dynamic failure process and characteristics of NdFeB under high-speed impact were explored, which provided an experimental basis for the following theoretical research. Given the theoretical deficiency of the dynamic mechanical properties of sintered NdFeB and the assumption of microcracks with uniform distribution and no friction, a theoretical model of damage evolution process of brittle materials was established based on the dynamic crack growth criterion. Combining the damage evolution model with Zhu-Wang-Tang (ZWT) constitutive model, the damage constitutive model of sintered NdFeB was established, whose validity was verified by the comparison with the experimental data.