Abstract
The objective of this study was to investigate the relationship between the scatter of fatigue crack growth rate and the scatter of fatigue life. Fatigue crack propagations were obtained in a wide range of stress amplitude under carefully designed four point out-of-plane bending fatigue tests in a constant temperature and humidity condition. The median S-N relations and the scatter of fatigue life presented in the authors' previous paper were used in this study. An empirical law of crack growth rate as a function of the bending stress intensity factor range was determined. An S-N equation was derived from this crack growth law and compared with the data of the median S-N relations. Using this S-N equation the relationship between the scatter of crack growth rate and the scatter of fatigue life was discussed and compared with the test results. It is concluded that the scatter of crack growth rate provides a reasonable estimate of the scatter of fatigue life.
