Application of the Weibull theory to an Nd-Fe-B rare earth sintered magnet was studied for use in evaluating the specific strength characteristics arising from the structure of this magnet. The validity of the Weibull theory was verified by the correlation with the Weibull distribution and by the existence of the size effect, whereby strength decreases with increases in size. The correlation with the Weibull distribution was verified by the close correlation shown by the resistance strength Weibull plot approximation line. While the existence of the size effect was verified due to the existence of the fixed relationship between effective volume, determined by the stress distribution, and fracture stress. Consequently, it was judged that the Weibull theory is valid for evaluation of the strength of this magnet. The strength of the magnet when incorporated into the rotor of a motor was also verified, thereby demonstrating the applicability of this theory to this type of magnet.
Article of Honda R&D Technical Review Vol.13 No.2 (225 - 230)