Distributions of Fatigue Life and Fatigue Strength in Notched Specimens of a Carbon Eight-Harness-Satin Laminate

The objective of this research is to investigate the distribution properties of fatigue life and fatigue strength in sharply notched specimens of a carbon fabric laminate, which was made of three layers of eight-harness-satin/epoxy prepreg sheets. Fatigue life distributions were obtained at six stress levels by carefully designed fatigue tests of four point plane bending under a constant temperature and humidity condition. Sample sizes were 30 for the three high stress levels and 12 for the three low stress levels. The amount of scatter and distributional form of fatigue life and fatigue strength are discussed from the test results. It is found that fatigue strength distributions are practically normal and their stand ard deviations are constant regardless of fatigue life.