Statistical aspects of some fatigue crack growth data

In this study, fatigue crack growth tests were performed for a considerable amount of specimens made of 2024T-351 aluminum alloy. In total, there are three data sets obtained, two of them are tested under constant-amplitude loading and the other under random loading. The results are reported in the present paper with special emphasis on the scatter and statistical aspect of these fatigue crack growth data. They are also compared with those of other available data sets. It is confirmed that the inhomogeneity of material does cause the scatter of fatigue crack growth. Whether the randomness of the applied load increases or decreases the scatter, however, needs to be investigated further since there is no unique result for all data sets compared. Crack exceedance probabilities of random crack size and cumulative distributions of random loading cycle obtained by solving probabilistic models of fatigue crack growth curves are also presented, and conclusions are drawn. Comments on chi-square goodness-of-fit test and equivalent loading investigation are made as well.