Finite Element Analysis of Specimen Geometry Effects on Fatigue Crack Closure

Elastic‐plastic finite element analysis is used to study fatigue crack closure at three different crack length to width ratios for three plane stress specimen geometries: center‐cracked plate, single‐edge‐cracked plate (tension), and single‐edge‐cracked plate (bend). The maximum stress to flow stress ratio, Smax/σO, which successfully describes closure results in many center‐cracked plate configurations, does not correlate the effect of different geometries on the normalized opening stress, Sopen/Smax. Crack opening stresses for different geometries and crack lengths are successfully correlated by a normalized stress intensity parameter, Kmax/K0, where K0=σ0φa. The quality of the correlation is very high at small Kmax/K0, and gradually deteriorates as Kmax/K0 increases beyond the small‐scale yielding regime.