Prediction of multistage fatigue curve based on the relaxation model of irreversible cyclic deformation

The paper studies the multi-stage fatigue dependence (Wöhler diagram) of the material and proposes a new model for its prediction based on considering the mechanisms of plastic deformation and fracture under cyclic loads and a combination of relaxation processes with the evolutionary development of damage, for which the initial condition is formed using the calculation calculated during the cycling process energy of irreversible deformation. The performance of the model is verified using the results of cyclic deformation tests on DP500 steel as an example. It is shown that within the framework of a unified approach it is possible to simultaneously evaluate the short-term, fatigue and long-term strength of the material.