Phase-field modeling of interactions between double cracks on brittle fracture of Zircaloy-4 cladding

Abstract The phase-field model was implemented in Abaqus via user-defined element (UEL) and user-defined material model (UMAT) subroutines for the brittle fracture analysis of a cladding tube. With this method, a scalar damage phase field was utilized to represent the diffuse crack topology, rather than numerical tracking of discontinuities in the cracking area. It was found that the burst hoop stress of the cladding was dependent on the competition of the interference effect and the damage field merging effect of double cracks. Moreover, there was a critical distance between the two cracks at which the burst hoop stress of the cladding reached a minimum. When the distance between two cracks was greater than the critical distance, the damage field merging effect was dominant, whereas when the distance was less than the critical distance, the interference effect was dominant. Furthermore, it was also observed that the burst hoop stress of the cladding was reduced due to the simultaneous initiation of two cracks.