Ratcheting assessment of visco-plastic alloys at ambient temperature by means of the A-V and O-W hardening rule frameworks

The present study evaluates ratcheting response of samples made of Z2CND18.12N Steel, Zircaloy-4, and 63Sn37Pb solder alloys subjected to asymmetric stress cycles with different stress levels and rates by means of the Ohno-Wang (O-W) and Ahmadzadeh-Varvani (A-V) isotropic-kinematic hardening rules. The framework of hardening rules was constructed on the basis of visco-plasticity constitutive equation to account for the effects of stress rate and time-dependency over ratcheting progress. Elements of visco-plasticity were adopted in the hardening rules on the basis of Chaboche's formulation to evaluate stress rate dependent ratcheting of materials at room temperature. The predicted ratcheting curves and stress-strain hysteresis loops on the basis of the O-W and A-V frameworks have compared with those of experimentally obtained. The A-V framework resulted in consistent ratcheting curves and hysteresis loops and better agreement with experimental data than the O-W framework at various stress ratios.