Normalised effective K versus L_r failure assessment diagrams as applied to a flaw in the vicinity of a stress concentration

摘要

Considerable use is now being made of failure assessment diagrams in order to quantify the effect of a defect on the integrity of an engineering structure. Regarding the effect of a sharp crack, it has been shown that the normalized stress intensity (K_r) versus normalized limit load (L_r) failure assessment curve is geometry dependent, this dependence being particularly strong for the case of a crack at the root of a stress concentration (blunt flaw). In this paper, we develop a failure assessment cve for such a situation, in terms of an effective K parameter. K_r is now defined in terms of the blunt flaw depth, but as if the blunt flaw were a sharp crack, and the effect of a crack at the root of the flaw is then described in terms of a modification to the blunt flaw failure assessment curve. This is a more appealing way of visualizing the effect of a sharp crack at the root of a blunt flaw.