Numerical simulation of fatigue crack growth and crack closure

Elastic-plastic finite-element analyses of the behaviour of cracks under cyclic loading have been conducted to study fatigue growth and crack closure with special emphasis on their possible effects on detecting and assessing surface cracks in realistic structural situations. Therefore, the finite element simulation accounts for non-line and cyclic material behaviour and changing boundary conditions as well as for load history (e.g. stress intensity factor range, peak loads) and stress state. The crack front was extended one element length per cycle when the applied load reached the maximum level. The numerical results verify known facts on fatigue crack growth retardation through a quantitative description of the influence of mechanical parameters on the crack closure effect and they demonstrate that the nondestructive evaluation of surface fatigue cracks may be more critical i.e. tending to underestimate its size, under plane stress than under plane strain conditions.