The comparison of complex load sequences tested at several stress levels by fractographic examination

This paper presents a summary of both the total life results as well as the crack growth rates for these specimens. Other aspects considered include the influence of the surface finish of the coupons and the identification of the nature of the crack initiation. This test program allowed two quite different spectra to be compared at several reference stress levels to determine the relative severity of each. Also sufficient numbers of specimens were tested to allow trends and scatter in the data to be fully evaluated.