Estimation of Fatigue Material Properties - Improvement of Existing Methods

The Method of Variable Slopes (MVS)' is proposed to predict the fatigue material properties for lifetime calculation of prestrained steel sheets, which is based on test series of 25 sheet steels. The method is based on Young's modulus, equivalent deformation level as well as the tensile strength. Because of the variable parameters the approximate solution is not only valid for sheet steels but in general for un- and low-alloyed steel of the database 'materials data for cyclic loading' by Boller, Baumel, Seeger. The well known 'Uniform Material Law (UML)' is modified by variable slopes to improve the results of fatigue lifetime prediction.