Scaling and fractality in fatigue crack growth: Implications to Paris’ law and Wöhler’s curve

Size effects on crack growth are of paramount importance on the fatigue problem. Paris’ and Wöhler’s fatigue curves exhibit scale effects, which can be explained in the framework of incomplete self-similarity and fractal geometry concepts. In particular, scaling laws are found for the main fatigue parameters, that is, the fatigue threshold ΔKth and the fatigue limit Δσfl. The fatigue threshold increases with the crack length, whereas the fatigue limit decreases with the specimen size. Eventually, the proposed models are positively compared to experimental data available in the literature.