Effects of residual stresses on crack-tip constraints

In this study, the effects of residual stresses on crack behavior are investigated in a large disk shaped model. The external load and crack-tip geometry constraint in the model are controlled by a remote boundary condition, which is a function of KK and TT-stress. A crack opening residual stress field, similar to a longitudinal residual stress field in butt welded plates, is introduced into the model using an initial strain field.For calculating the modified, path independent, J-integral in the specimens with residual stresses, a post processor for finite element results was developed by computer programming. To carry out a systematic investigation into the effect of residual stresses on crack behavior, the constraint parameters, Q and R, for different combinations of residual stresses and external loads, were calculated, and the interaction between residual stresses and external loads for different models was studied. It has been shown that the crack driving forces and the crack-tip stress field were significantly influenced by residual stress.