Generalization of cumulative damage criterion to multilevel cyclic loading

Abstract

A cumulative damage theory is presented for multilevel cyclic loading. Both the crack initiation and propagation stages are included in this method. The criterion is based on the concept of the total strain energy density as a damage parameter. The effect of the mean stress/strain on the damage accumulation is also included in this formulation. It is shown that a number of earlier proposed models can be derived as a particular case of the present criterion. The predicted results are compared with the experimental data of two, three, five and six steps cyclic loading histories. A good agreement is noted between the predicted and experimental results.