A finite deformation elasto-plastic cyclic constitutive model for ratchetting of metallic materials

A finite deformation elasto-plastic cyclic constitutive model is developed for the ratchetting behavior of metallic materials. Compared to existing models, an improved description is achieved by introducing a modified “A-F” kinematic rule and a nonlinear isotropic hardening rule proposed by Chaboche. In the proposed kinematic hardening rule, the back stress is decomposed into two parts, with each addressing an “A-F” evolution rule consisting of a linear hardening and a dynamic recovery term - as done by Armstrong and Frederick. The dynamic recovery coefficients are postulated here to decrease with deformation, instead of being constants as per standard A-F rule. In addition, a ratchetting coefficient is introduced into each dynamic recovery term to better describe the ratchetting behavior. The predictive capability of the proposed model is demonstrated by benchmarking its results against experimental data for monotonic stress-strain responses, cyclic hardening and ratchetting behavior of metallic materials.