Development of statistical methods to highlight differences between endurance limit of re-rolled steel sheets in an assumed homogeneous population

In this paper, we present the results of the activities carried out to estimate the axial fatigue strength of ASTM E566 Gr. 70 sheet metal. We describe the experimental setup, followed by the collected data. To highlight a possible inhomogeneity in some of the material properties, we estimate the endurance limit for the investigated material using various statistical approaches on the set of test articles. The data analysis was carried out both by considering as a whole the set of test articles and by dividing the set into two groups. As a new analysis technique, we propose a method introducing a bimodal distribution (Gaussian mixture)