A New Type of S–N Equation and Its Application to Multi-Axial Fatigue Life Prediction

Abstract

The S–N equation is one of the most important equations in fatigue model investigation. A majority of fatigue models, including multi-axial fatigue model and mean effect models, are established on the basis of the S–N equation. Obviously, an accuracy of the S–N equation is very important. Taking into account that the S–N equation is, in fact, an empirical one in which the material constants are determined by numerical fitting fatigue experimental data, in this study, the S–N equation can be improved, by further processing these fatigue experimental data, to present a new type of S–N equation that is more accurate than the S–N equation. The new type of S–N equation is called a similar S–N equation in this study. By using a large number of experimental data of metallic materials reported in the literature, an accuracy of the similar S–N equation has been proven.