Cyclic plastic deformation response at fatigue crack tips

To determine the nature of damage acting on a fatigue crack-tip, it is mandatory to know the detailed cyclic plastic deformation response. In this work, cyclic plastic deformation response has been studied on a stationary CT specimen crack-tip in an elasto-plastic finite element frame work at selected R-ratios and DeltaK. Chaboche kinematic hardening model has been used to describe material behavior. Monotonic and cyclic / reverse plastic zone has been identified during plane strain finite element analysis. It is noticed that progressive accumulation of permanent strain i.e. ratcheting occurs in the cyclic plastic zone ahead of a fatigue crack-tip.