Verification of a Polynomial Stochastic Fatigue Crack Growth Model

The study is focused on the verifications of a proposed polynomial stochastic fatigue crack growth model, which assuming the fatigue crack growth rate equal to a deterministic polynomial function in terms of fatigue crack size multiplied by a stationary lognormal random factor accounting for the statistical scatter of the fatigue crack growth. Compact tension (CT) specimens cut from a 2024-T351 aluminum-alloy plate were used for fatigue crack growth tests under random loads performed on twenty-five specimens. The comparison of median crack growth curves was made between analytical and experimental outcomes. For extreme case of lognormal random variable, the comparisons of the fatigue crack growth curve, percentile fatigue crack growth curve, probability of crack exceedance, and distribution function of random time between analytical and experimental results were also investigated.