Abstract:

The Item presents a method for the analysis of acoustic fatigue data where the life, or the number of cycles to failure, has been measured for different stresses (or strains) applied to small structural elements or coupons. The S-N (or ε-N) curve is obtained by linear regression. The 95% confidence intervals for the population regression line, using either Student's t distribution or the F distribution are given. A MATLAB computer program in p-code is available for which the input can be introduced either through the keyboard or by means of an input file. Direct graphical output of the fitted line and the 95% confidence intervals is provided. A further part of the program checks if the linear regression model is adequate. If the linear model is shown to be inadequate, where possible, a quadratic model is investigated.