II. The elastic limits of iron and steel under cyclical variations of stress

Abstract

Introduction . Since Wöhler’s original experiments on the fracture of iron and steel by repetition of stress, similar experiments have been made by independent observers, and all agree in showing that neither the maximum tensile strength nor the yield stress hears any simple relation to the range of stress which may be safely repeated. The only theory of fatigue, i . e . of failure due to repetition of stress, which has received serious attention was put forward by Bauschinger. According to this theory, specimens subjected to repetitions of stress begin to be fatigued when the stresses applied in each cycle are so great that the extension of the specimen is not wholly elastic.