Fracture Initiation in Compact Tension Specimens of Hydrided Irradiated Zr-2.5Nb Materials With Split Circumferential Hydrides

Fracture initiation in compact tension (CT) specimens of hydrided irradiated Zr-2.5Nb materials with split circumferential hydrides is examined by conducting three-dimensional finite element analyses with submodeling. The stress-strain relation for the irradiated Zr-2.5Nb materials is based on the experimental results of transverse tensile tests. For CT specimens with split circumferential hydrides, plastic strain concentration is observed in the middle of the ligaments ahead of the crack front. With a strain-based failure criterion with consideration of stress triaxiality, the necessary fraction of the load for crack initiation is about 0.55 to 0.70 to fracture the ligaments when compared to that for a CT specimen without split circumferential hydrides. The computational results can be used to explain the near 40% reduction of the fracture toughness at room temperature obtained from hydrided irradiated curved compact tension specimens (CCTSs) when compared with that from unhydrided irradiated ones.