Numerical Simulation Of The Fatigue Nonproportional Hardening Rule Under Nonproportional Loading

In all failures, about 50% to 90% is due to cyclic loading and fatigue damage from lots of literatures. Fatigue response due to complicated loading (much are non-proportional loading) has been the subject of fatigue experimental, theoretical and analytical investigations. Critical experiments, theories and models of comparison to quantify non-proportional hardening are presented.In this article we use Jiang's constitutive model. In this model, a new kinematic hardening equation was used; the non-proportionality, the effect of memorization for the maximum plastic strain amplitude were considered. It is shown from the simulated result that the model can describe the non-proportional multiaxial deformation behavior and cyclic hardening behavior.The constitutive model was implement into the finite element program ABAQUS by user-subroutine UMAT. Based on radial method and back Eular integration, a new implicit stress integration algorithm was proposed. Simultaneously, a new expression of consistent tangent modulus was also derived. Numerical examples of a 304 stainless steel were given. The results which showed that the finite element simulation was successful was almost the same with the experiments.