Study of Threshold Stress Intensity Factor and Fatigue Limit for through Crack in Infinite Plate and Semi-Elliptical Surface Crack in Finite Plate

Linear fracture mechanics can quantitatively address the problem of cracks in metals and ceramics. In particular, the fracture toughness (K-c) and threshold stress intensity factor (Delta K-th) of fatigue crack propagation depend on the crack size. Linear fracture mechanics assume that the plastic zone or nonlinear zone occurring at the crack tip is very small compared to the crack size. However, short cracks do not satisfy this condition. Hence, the threshold stress intensity factor (Delta K-th) and the fatigue limit (Delta sigma(omega)) of short surface crack size due to fatigue load were evaluated using an equation that considers the stress ratio and the plastic behaviors of peculiar fatigue proposed by Ando et al. In addition, the through crack of the infinite plate was evaluated for comparison.