Theory model combined with XFEM of threshold stress intensity factor and critical hydride length for delay hydride cracking.

In order to determine the threshold stress intensity factor and critical hydride length for delayed hydride cracking in Zr-2.5Nb pressure tube alloy, the distribution of normal stress in the plastic zone of crack tip by the developed method that combines theory calculation with extended finite element method (XFEM) was improved. The fracture process of two-phase composites containing Zr-2.5Nb and hydride precipitate was simulated by XFEM. Based on that, critical hydride length L C corresponding to the theoretical model for K 1H was estimated. Meanwhile, to illustrate the validity of theoretical and numerical methods, recent theoretical models and experimental measurements were utilized to verify the results of this paper. The theoretical model of DHC was improved to estimate the critical hydride length corresponding to threshold stress intensity factor. The predicted value of critical hydride length is close to the experimental values. • Distribution of the normal stress in plastic zone is improved by valid estimation of σ 0. • The theoretical model combining XFEM is used to calculate the K 1H and L C. • The influence of hydride size on the instability fracture point is revealed by XFEM. [ABSTRACT FROM AUTHOR]