Abstract：Sintered Nd-Fe-B which is a typical hard magnetic material, crises characterized by unexpectedness, uncertainty, and urgency during fatigue cracking. Therefore, it is difficult to monitor its fatigue damage propagation process online. In order to realize the online monitoring the whole process of fatigue damage expansion for sintered Nd-Fe-b during its long-time service, the fatigue state evolution equation of sintered Nd-Fe-B under the geomagnetic field environment is constructed by utilizing coupling effects of stress and magnetic. The magnetic induction value is used as the state parameter to describe the fatigue damage. The magnetic induction intensity of the weak magnetic which is collected by high precision magnetic sensor is used to monitor the fatigue damage prop-agation process online. The fatigue test results show that: it can accurately predict the point of fracture in time during fatigue damage propagation process for sintered Nd-Fe-B by the trends of the magnetic induction intensity value and the residual value of the polynomial fitting curve. Meanwhile, the variation of magnetic induction signal curve reflects the whole process of Nd-Fe-B fatigue damage propagation under stress without distortion.
2021, Vol. 42 
