A simplified estimation procedure for the Weibull stress parameter, m, and applications to predict the specimen geometry dependence of cleavage fracture toughness. (December 2020) - Barbosa, Vitor S.
Abstract: This study describes a simplified procedure to estimate the Weibull stress parameter, m, using cleavage fracture toughness values measured from testing high constraint fracture specimens. The estimation procedure builds upon the conventional toughness scaling methodology (TSM) based on the Weibull stress coupled with the weakest link model to correct measured toughness distributions for high constraint fracture specimens with identical in-plane dimensions but varying thickness. The approach thus requires a correspondence between predictions based upon the Weibull stress methodology and the weakest link model for measured toughness values under high constraint conditions. Applications of the proposed procedure to analyze specimen geometry effects on fracture toughness values in a typical structural steel provide predictions that agree remarkably well with experimental data for shallow crack bend specimens with different thickness. These exploratory studies demonstrate the potential capability of the proposed estimation procedure which can greatly simplify engineering integrity assessments based upon the Weibull stress model. Highlights: Proposal of a new simplified procedure to estimate the Weibull stress parameters. Use of only one set of toughness data is required in the simplified estimation procedure. J c -values for a shallow crack SE(B) specimen with reduced thickness display significant toughness elevation. Application of the simplified procedure highly effective in predicting the geometry dependence of J c -values. Further simplification incorporating the Master Curve method predicts fracture behavior directly from CVN energy.