Research on Techniques of Establishing Random Type Fatigue Curves for Broad Band Sonic Loading

The Boeing program to investigate methods for establishing fatigue curves for broad band random loading is described. The approach used was to absorb the trends indicated by the results of the experimental program, together with the results of other investigations, into an expression involving the constant cycle S-N relationship, the root mean square stress, and other simple parameters which could be derived from the random load stress power spectrum and from the appropriate stress frequency distributions.