Analysis and application of fatigue crack growth data

TLDR: The fracture mechanics concept of stress intensity factor has proved particularly convenient for the analysis of fatigue crack growth data in a form which can be applied directly to engineering problems, and its use has led to a much better understanding of the fatigue behaviour of structures as discussed by the authors.

Abstract: The phenomenon of metal fatigue has been studied for a long time, but it has only relatively recently been appreciated that most structures, particularly welded joints, contain crack-like flaws, so that virtually the whole fatigue life is occupied by fatigue crack growth. The fracture mechanics concept of stress intensity factor has proved particularly convenient for the analysis of fatigue crack growth data in a form which can be applied directly to engineering problems, and its use has led to a much better understanding of the fatigue behaviour of structures. The effects of interaction between different load levels are not yet fully understood; this is not necessarily a serious drawback as servo-hydraulic fatigue testing equipment permits the application of virtually any load history to structures or fatigue crack growth specimens.