Uniaxial ratchetting of 316FR steel at room temperature - Part II: Constitutive modeling and simulation

Uniaxial ratchetting experiments of 316FR steel at room temperature reported in Part I are simulated using a new kinematic hardening model which has two kinds of dynamic recovery terms. The model, which features the capability of simulating slight opening of stress-strain hysteresis loops robustly, is formulated by furnishing the Armstrong and Frederick model with the critical state of a dynamic recovery introduced by Ohno and Wang (1993). The model is then combined with a viscoplastic equation, and the resulting constitutive model is applied successfully to simulating the experiments. Ii is shown that for ratchetting under stress cycling with negative stress ratio, viscoplasticity and slight opening of hysteresis loops are effective mainly in early and subsequent cycles, respectively, whereas for ratchetting under zero-to-tension only viscoplasticity is effective.