Effect of a Stress Cycle Waveform on the Life at Cyclic Loading

When analyzing a generalized S–N curve, we assume that the fatigue life changes when a loading cycle waveform changes (sinusoidal and peaked waveforms are considered). Theoretical approaches to taking into account the influence of a cycle waveform different from sinusoidal on the life are presented. The results of fatigue tests carried out using a unique technique at two stress levels confirm the theoretical postulates that the median values of the life in the case of a peaked loading cycle are larger as compared to the life at a sinusoidal loading cycle: their ratio is approximately 1.3.