A New Damage-Coupled Cyclic Plastic Model For Whole-Life Ratchetting Of Heat-Treated U75v Steel

In the framework of continuum damage mechanics, a new damage-coupled cyclic plastic model is proposed to describe the nonlinear evolution of whole-life ratchetting and its dependence on the stress level. The characteristic that the damage evolution rate of U75V heat-treated steel decays in the initial load cycles is considered by introducing a modified term into classic damage evolution equation. A hybrid fatigue failure criterion considering both the fatigue and ratchetting strain-induced failures is established based on the fatigue failure rule concluded from experiments. Comparisons between simulated and experimental stress-strain hysteresis loops, ratchetting strains, damage evolutions, and fatigue lives are performed to validate the proposed model.