Hysteresis Loop Analysis in Cyclically Strained Materials

Abstract

The generalized statistical theory of the hysteresis loop is adopted to describe the stress-strain relations, preferably in cyclic straining. The effective stress and the distribution of the internal critical stresses in cyclic straining are evaluated in two materials cycled at room and at elevated temperatures using the analysis of the hysteresis loop shape. The evolution of the shape of the probability density function of the internal critical stresses yields deeper insight into the mechanisms of cyclic plastic straining. It indicates the important role of cyclic plastic strain localization in room temperature fatigue softening. The approximation of the probability density function by Weibull distribution leads to the assessment of the effective and internal stresses and allows the simulation of the relations between the stress and strain in case of different cyclic histories.