Ductile fracture initiation with consideration of strain concentration and stress triaxiality near crack fronts in compact tension specimens of hydrided irradiated Zr-2.5Nb materials with split circumferential hydrides

Ductile fracture initiation with consideration of strain concentration and stress triaxiality near crack fronts in compact tension specimens of hydrided irradiated Zr-2.5Nb materials with split circumferential hydrides is investigated by three-dimensional finite element analyses. The results indicate that plastic strain concentration is observed in the middle of the ligaments ahead of the crack front. A strain-based failure criterion with consideration of stress triaxiality is developed from the Gurson yield model. With the failure criterion, the necessary fraction of the load for crack initiation is about 0.60-0.70 to fracture the ligaments when compared to that for a CT specimen without split circumferential hydrides.