The influence of cyclic stress intensity threshold on fatigue life scatter

Cyclic-fatigue crack growth in composite and adhesively-bonded structures: The FAA slow crack growth approach to certification and the problem of similitude

“…There are several ways in which this master curve can be determined. The recent reviews of the field of fatigue crack-growth and damage-tolerance [32,36] has revealed that, in metals, the effects of (a) changing the R-ratio, (b) the variability seen in the growth of both 'long cracks' and 'short cracks', and (c) fatigue cracks that grow from small naturally-occurring material discontinuities may all be modelled using a form of the Hartman-Schijve crack-growth equation, which as explained in [32] is a variant of the NASGRO Equation [37]. These equations are based on the premise that the value of da/dN is not governed simply by the value in ΔK seen in a cycle but rather by the amount that ΔK is greater than its threshold value [38].…”

“…The Hartman-Schijve equation used in [1,8,11,20,24,25,32,36,[39][40][41][42][43][44] is basically an empirical equation that for metals takes the form:…”

“…and, as explained in [20,32,36], the values of A and ∆K thr are chosen to ensure that Equation (7) captures the entire crack growth history. This approach has the advantage that it can represent the growth of both long and small, naturally-occurring, cracks and can capture the variability seen in crack-growth histories as observed in both constant amplitude and operational flight-load spectra [24,32] as well as the coalescence of small cracks and their subsequent growth.…”

Local Monte Carlo Method for Fatigue Analysis of Coarse-Grained Metals with a Nanograined Surface Layer

“…Linking the probability distribution of the local fatigue threshold in Ref. [58,59] with that of the local fracture properties in our numerical model and to establish the relationship between the parameters in the above two probability distributions is stimulating to provide more insights into the fatigue life of metallic materials or structures.…”

“…For a given surface roughness, the probability distribution of lead crack growth rate and hence fatigue life can be determined by that of the local fatigue threshold, and the role of the fatigue threshold is the effect of surface roughness [58,59]. Linking the probability distribution of the local fatigue threshold in Ref.…”