Numerical Simulation Of Non-Massing Behavior Under Cyclic Strain Loading

At present, the cyclic stress– strain (CSS) curve is always distributed to describe cyclic behavior of material during the strain fatigue analysis. For the material that displays massing behavior, the method mentioned above is successfully available. However, for the material with non-massing behavior, if we still use the massing assumption to describe the hysteresis loop, then it will cause large errors.In this thesis, Jiang-Sehitoglu's constitutive model is modified to predict the non-massing behavior of material. We introduce the evolution equation of the back stress, non-proportional hardening parameter as well as the invariable radius of the yield surface and other characters to the model. Then we establish the constitutive model for simulating the non-massing behavior. Based on radial method and back Euler integration, new stress and back stress integration algorithm are proposed. The constitutive model is implement into the finite element program ABAQUS by user-subroutine UMAT. Numerical example of the polycrystalline copper is given. The result shows that the finite element simulation is almost the same with the experiment.