An elastoplastic-damage model based on nonlocal peridynamic theory for ductile damage analysis under cyclic loading

In this paper, a new thermodynamically consistent model is presented for predicting the elastoplastic-damage behavior of ductile materials using the ordinary state-based peridynamic theory. The innovative idea of this paper lies in the definition of a damage variable for each material point to simulate deterioration. By coupling the newly defined damage variable with the elastoplastic formulation, the presented peridynamic model is capable of demonstrating the initiation and evolution of damage in ductile materials subjected to cyclic loading. In this paper, the consideration of damage is based on phenomenological aspects. To capture this phenomenon, suitable state variables and corresponding thermodynamical forces are defined and isotropic and kinematic hardenings are incorporated based on the equivalent plastic stretch. By defining a dissipation potential that adheres to the requirements of the second law of thermodynamics, the presented peridynamic constitutive model achieves its purpose and the evolution laws for internal variables are derived from the defined dissipation potential. The numerical results, obtained through the employed integration algorithm, demonstrate that the presented peridynamic elastoplastic-damage model can accurately predict the initiation and growth of damage. Furthermore, the model exhibits the capability to simulate the behavior of low cycle fatigue and accurately predict material fatigue failure.