Analysis of fatigue crack closure behavior for various cracked geometries

A new crack closure analytical model was used to calculate the fatigue crack opening stresses for two cracked geometries (single-edge-cracked tensile plate and single-edge-notch-cracked tensile plate) with a larger crack length at two stress ratios. The results were combined with the previous ones to further study the crack closure behavior for four cracked geometries with different crack lengths under plane stress condition. The results showed that the crack closure behavior is obviously affected by specimen geometry, stress ratio and finite width of specimen. The normalized maximum stress Smax/sigma(o), maximum stress intensity factor Kmax, and Kmax/Ko (where K-o = sigma(o) root pi a> were used to correlate the effects of different geometries on the normalized crack opening stress, So/Smax. It was found that only Kmax/Ko can successfully correlate So/Smax under small scale yielding condition.