COUPLING THE EFFECTS OF CONSTRAINT AND PLASTIC STRAIN IN CLEAVAGE FRACTURE TOUGHNESS PREDICTIONS: A MODIFIED WEIBULL STRESS MODEL

摘要

1. Introduction The fundamental importance of cleavage fracture behavior in structural integrity assessments has stimulated a rapidly increasing amount of research on predictive methodologies to quantify the influence of crack-like defects on the load carrying capacity of structural components. The seminal work of the French Beremin group attains particular relevance as it has served as the basis for generalizing the concept of micromechanics modeling for cleavage fracture (also often referred to as local approaches) which in turn has enabled the development of approaches highly effective in unifying toughness measures across different crack configurations and loading modes. A key feature of the Beremin approach is the introduction of a local crack driving force, termed the Weibull stress, which provides the necessary framework to correlate fracture toughness for varying crack configurations under different loading conditions. However, a potential drawback with the Beremin model lies in the non-recognition of the strong role played by the plastic strain at the microlevel on cleavage fracture and associated cleavage failure probability.