A local criterion for cleavage fracture of a nuclear pressure vessel steel

Analysis of notch effect in load bearing capacity, apparent fracture toughness and fracture micromechanisms of ferritic–pearlitic steels

“…Moreover, as mentioned above, the notch effect modifies the stress field at the notch tip, and therefore it is actually a source of loss of constraint (e.g., [28][29][30][31][32][33][34]). This has led to notch analyses based on two parameter fracture mechanics, especially those based on the T-stress (e.g., [35,36]).…”

Experimental – Numerical Analysis of Stress State in Front of the Crack Tip of Modified and Unmodified G17CrMo5-5 Cast Steel by Rare Earth Metals in a Brittle-Ductile Transition Region

“…On the basis of the numerical analysis of the fracture process carried out in the paper, obtained some values that allow to explain peculiarities of development of the cracking process in the UM and M cast steel. According to the local approach to fracture, the initiation of the subcritical crack growth will exist, if the level of stresses and/or strains achieves a higher level than the critical, on some critical length of section [7][8][9][10][11]. In the local approach to fracture, proposed by Ritchie, Knott and Rice (RKR), it is assumed that the fracture process is possible if the level of the opening stresses σ zz exceeds the critical value.…”

“…According to the local approach to fracture, the fracture process begins if the level of stresses (or strains) in front of the crack, exceeds the critical value on the critical distance [7][8][9][10][11]. The modified Ritchie-Knott-Rice's criterion for the beginning of fracture process determines a level of the opening stress that must be exceeded on the critical distance [12,13].…”

Cleavage Fracture Modeling of Pressure Vessels under Transient Thermo-Mechanical Loading

“…The widely adopted "weakest link model" assumes that fracture of a material volume depends on a single initiator [22][23][24], or equivalently a single microcrack. Weakest link concepts form the technical basis for the first testing standard developed specifically to address the unique statistical issues with ferritic steels at temperatures over the DBT region (ASTM E1921 [19] By correlating an assumed, inverse-power density distribution of critical microcrack sizes with the local stress through a simple fracture mechanics model, the Beremin group [6] derived the cumulative failure probability for a two-parameter Weibull stress model,…”

“…The probabilistic Weibull stress ( w σ ) framework for cleavage fracture, originally proposed by the Beremin group [6,7], considers material toughness and loading "local" to the immediate crack front region and thus applies when I K or the J-integral no longer describe the crack front displacement-strainstress fields under increasing plastic deformation. The fracture process zone represents small, but finite, volumes of material which fully embody a population of microscale flaws, whose size and density constitute material properties.…”