Comparison of different methods for presenting variable amplitude loading fatigue results

This paper discusses eight methods for presenting fatigue test results for variable amplitude loading and their comparison with constant amplitude loading. While the maximum amplitude method compares constant and variable amplitude loading results by the Woehler and Gassner curves, all other seven methods try to transform the variable amplitude results into the Woehler curve by applying different equations. The advantage of the maximum amplitude method is the direct comparison of the maximum amplitude of the spectrum with the yield strength and with the high-cycle fatigue strength, which is an important step in structural design. Among the other methods, the best results were obtained by following: most damaging, half damage and mean damage amplitudes. However, the presentation of constant and variable amplitude results by these methods in one scatter band is possible only when the real damage sum is close to D = 1.0.