Abstract:

Fatigue results are presented for coupons made from titanium and titanium alloys, which are subjected to narrow band random loading, intended to simulate acoustic loading. The coupons are cantilevers or in the form of T-shaped structures. The results are presented as the common logarithm of the root mean-squared stress versus the logarithm of the equivalent endurance, or the number of cycles to failure. The S-N graphs given are relevant to the study of acoustic fatigue of titanium structures and enable the life of a structure under acoustic loading to be estimated.

A linear relationship is assumed between the logarithm of the stress and the logarithm of the equivalent endurance. The equation of the S-N curve is obtained by the method of least squares fit. With the assumption that the logarithm of the endurance is the dependent variable, the 95% confidence intervals have been established, based on Student's t distribution.

For a given coupon configuration the results presented include (i) the least squares logS - logN graph, (ii) the equation of the S-N with 95% confidence intervals and (iii) a diagram of the configuration.