An engineering methodology for constraint corrections of elastic–plastic fracture toughness – Part I: A review on probabilistic models and exploration of plastic strain effects

• Extensive survey of the considerable work in statistical modeling of cleavage fracture.
• Development of limiting distributions for fracture stress including plastic strain effects.
• Introduction of a modified Weibull stress incorporating plastic strain effects.
• Fracture resistance depends on the adopted plastic strain model.
• Inclusion of plastic strain effects reduces constraint corrections in toughness predictions.

This work describes a micromechanics methodology based upon a local criterion incorporating the effects of plastic strain on cleavage fracture coupled with statistics of microcracks. A parameter analysis is conducted under well-contained plasticity, where near-tip fields with varying constraint levels are generated through a modified boundary layer formulation. These analyses are extended to assess the effects of plastic strain on fracture toughness correlations for conventional SE(B) specimens with varying a/Wa/W-ratios. Fracture toughness predictions for a pressure vessel steel tested in the DBT transition region based on the proposed methodology are considered in Part II of this article.