Ductile fracture prediction of an axially cracked pressure vessel under pressurized thermal shock

In this paper, the J-value of an axially cracked cylinder under thermal shock, internal pressure and several pressurized thermal shock (PTS) conditions are evaluated over the full range of crack depth ratio (ξ) using a simple estimation scheme based on the deformation theory of plasticity which we proposed in our earlier works. Several parameter studies show characteristic features of the fracture strength under PTS as follows, (1) The effect of internal pressure is predominant upon the J-value and dJ/da under PTS. (2) Under any PTS condition, J-ξ relation shows that the J-value reaches its maximum at a certain ξ, then drops to zero (i.e., the starting point of crack closure) atξ≅0.9. (3) The compliance of the cylindrical shell plays an important role in the fracture prediction of a pressure vessel. (4) Under typical PTS conditions, the region at the crack tip dominated by the Hutchinson-Rice-Rosengren singularity is substantially large enough to apply the J-based criterion to predict unstable ductile fracture. (author)