Energy based analysis of crack tip plastic zone of AA2024-T3 under cyclic loading

The plastic zone at a crack tip of the commercially available aluminum alloy AA2024-T3 was energetically analyzed by digital image correlation and coupled FEM simulations. In mode I, mode II and mixed mode experiments the crack tip was cyclically loaded by the same maximum equivalent stress intensity factor. In every load maximum and minimum a digital image of the crack tip area was taken to compute the displacement field using digital image correlation (DIC). The computed displacement field was mapped on the nodes of a 2d FE-model. Using a bilinear isotropic hardening model the stresses and the plastic strain energy as a measurement for the damage accumulation in the plastic zone was computed. Beyond that a postprocessor for the DIC based strain fields has been programmed to calculate the actual stress intensity factors during cyclic loading.