Constraint effects on initiation and growth of a fatigue crack

The specific role of stress-state on the simulation of initiation and growth of a mode-I fatigue crack is examined. The crack growth curves for a plane strain model of a compact test specimen are generated by modelling fatigue damage process by a triaxiality dependent cohesive law for fatigue. In comparison to conventionally fixed cohesive laws, the stress-state dependent cohesive law for fatigue is shown to be more effective in reproducing characteristic features of experimental fatigue data as a consequence of its ability to account for the differences between the stress-state during the initiation of a fatigue crack ahead of a notch and during the propagation of a growing crack.