A Simple Criterion for Fracture Initiation at the Root of a U-Shaped Flaw

Motivated by the problem of Delayed Hydride Cracking (DHC) at the root of a blunt flaw in Zr-Nb CANDU pressure tube material, the author has developed a simple criterion which quantifies fracture initiation at the root of a blunt flaw. The criterion, which is based on a simplified version of the process zone procedure, is quite general and can be applied to a wide range of situations, and in this paper it is applied to the problem of fracture initiation at the root of a U-shaped flaw in a brittle material. The results compare favourably with finite element results obtained by other workers, the agreement providing useful underpinning for the simplified procedure. Moreover, and most importantly, since the finite element results have been shown to compare favourably with experimental results for a wide range of materials, the implication is that the author’s approach is also validated experimentally. This validation is important since it provides added confidence with regard to the application of the author’s application of the simplified version of the process zone procedure to the DHC problem.