Structural engineers are becoming increasingly aware of the possibility of structural fatigue failures and are considering it with greater frequency in structural designs and design criteria. At the present time, (1969) and in the immediate future, no analytical methods exist with which service life of structural members may be predicted. Instead, laboratory fatigue tests must be conducted on the members and details, and the prediction of life is based on analysis of the data. Structural fatigue tests are expensive and time consuming and, in general, relatively few specimens are tested. It is, therefore, necessary to design the fatigue testing program in the most efficient manner to permit extraction of a maximum in meaningful data with statistically defined confidence. The experimental construction of S-N curves (stress versus fatigue life) is the most common type of structural fatigue test program. The S-N curves may be used either to compare materials or details (treatments) or as the basis for service life predictions. The writer presents a suggested method for the determination and analysis of an S -N curve and describes its application to small sample sizes.
"Procurement and Analysis of Structural Fatigue Data," Journal of the Structural Division, Proceedings of the American Society of Civil Engineers , v. 95, ST7, July 1969, pp 1533-1551.