Numerical implementation for the cyclic elasto-plasticity model of Inconel 690 considering cyclic hardening followed by softening☆

This study investigates the cyclic elasto-plastic behavior of the nickel-based alloy 690 under fully reversed uniaxial strain load at room temperature. Through a series of experiments, it is found that the material undergoes initial cyclic hardening followed by prolonged softening. The strain range effect is also observed, as the rate of cyclic hardening/softening is influenced by strain amplitudes. To capture these behaviors, a nonlinear kinematic hardening rule combined with the strain memory surface is introduced, and the saturated value of backstress is considered as a function of both the accumulated plastic strain and the radius of the memory surface. Subsequently, the backward Euler method and the implicit integration algorithm are applied for numerical implementation. A user material subroutine UMAT is developed for the commercial software ABAQUS. Numerical simulations are conducted on the experiment specimens to validate the constitutive model. The results indicate that the model can describe the cyclic elasto-plastic behavior of the nickel-based alloy 690.