Fatigue Crack Growth Kinetics in a 2024-T3 Aluminum Alloy during Alternating Cyclic Loading

The fatigue crack growth kinetics in a 2024-T3 aluminum alloy during constant- and variable-amplitude loading a various stress ratios in the medium-amplitude segment of a fatigue crack growth rate curve is studied. Variable-amplitude loading is represented by quasi-random samples of standard random loading spectra, which were preliminarily schematized using a rainflow algorithm. Parameters are proposed to estimate the character of random loading. The influence of the character of random loading using various standard spectra on the fatigue crack growth rate is analyzed. The fatigue crack growth time is estimated with allowance for fatigue crack closure and the character of random loading using a proposed formula and a cycle-by-cycle calculation method.