Numerical simulation of fatigue crack growth

A numerical simulation of fatigue crack growth which uses currently available crack tip stress and strain fields is described. The essential features of the numerical model are the concepts of damage accumulation cycle by cycle and repeated re-initiation at the tip of the growing crack. The failure criteria employed are a combination of a failure condition and a critical distance over which this condition must be achieved. This critical distance, the material size parameter, has a magnitude which depends on the failure mechanism.

The use of the model to illustrate the effects of stress ratio and environmental effects is described and the ability of the model to predict the onset of bursts of crack growth due to static failure mechanisms is demonstrated. The phenomenon of self-arresting cracks is also displayed.

Material characteristics are included in the model and comparisons with experimental data are presented for a C-Mn steel used in the fabrication of offshore structures.