Calculation of inelastic notch-tip strain-stress histories under cyclic loading

Abstract

An application of the equivalent strain energy density method for calculation of elastic-plastic notch-tip strains under cyclic loading is presented. It is shown that the theoretical notch-tip strain calculations can be improved if the stress redistribution due to the plastic yielding around the notch-tip is taken into account. The energy density method, corrected for plastic yielding gave good results almost up to the general plastic yielding, i.e. S = σ ys . It was also found that a universal function for the elastic stress distribution ahead of a notch tip can be derived for both tension and bending loads. Several different notches and materials were analyzed. The equivalent strain energy density concept can easily be used for a simulation of the notch-tip cyclic stress-strain history if the stress concentration factor K t , the cyclic stress-strain curve σ−ϵ and nominal stress/load history are known. Good notch-tip strain predictions were achieved for both the monotonie and cyclic load.