A Comparison of Notch Failure Assessment Diagram Methods for Assessing the Fracture Resistance of Structures Containing Non-Sharp Defects

This paper analyses and compares a range of Notch Failure Assessment Diagram (NFAD) methods for assessing the fracture resistance of structures and components that contain defects with non-sharp tips. As micromechanistic failure criteria for predicting fracture from notch tips have developed, several forms of NFADs have been proposed over the last 20 years with notable developments having been made in the last 10 years. This paper quantifies the differences between four different types of NFAD approach and uses test results from test specimens containing notches of varying acuities to evaluate each approach. The results highlight significant differences in fracture predictions between the different NFAD approaches due to differences in the definition of the NFAD axes, the failure loci, the assumed failure mechanism and the corresponding micromechanistic failure criteria employed by each method.