抄録
The stress intensity factor of an elliptic toroidal crack which consists of the nested sequence of two elliptics is caluculated by using the finite element method. The three dimensional isoparametric singular elements are used for taking into consideration the singulality of strain at the tip of such a crack, and they are arranged so as to surround the crack tip. In element subdivision, the geometry of the singular element whose edge corresponds to the crack front is designed to be a fan on the crack surface. Namely, the corner angle of the singular element is designed to be right. It can be seen from numerical results that the value of the stress intensity factor at the inner tip of the elliptic becomes always greater than that at the outer tip and its maximum value occurs at the crack tip on major axis of the inner elliptic. Therefore, the inner elliptic of the elliptic toroidal crack is considered to propagate to be circular.
