An anisotropic Gurson type model to represent the ductile rupture of hydrided Zircaloy-4 sheets

The aim of this work is to model the ductile fracture of Zircaloy-4 sheets containing various amount of embrittling hydride precipitates. The proposed model is based on the Gurson-Tvergaard-Needleman model which is extended to take into account plastic anisotropy and viscoplasticity. The mechanical behavior is identified by conducting tensile tests and the damage nucleation rate (hydride cracking) is measured using quantitative metallography. The model is then used in a Finite Element software to represent crack propagation in Center Crack Panel specimens. Results are strongly mesh size dependent. The mesh size has to be identified by comparison with experimental results. Finally the model is validated by simulating crack initiation and growth in moderately complex structures (sheets containing holes).