رشد ترک خستگی با اضافه بار در زیر بارگذاری طیف

Load cycle interactions can have a very significant effect in fatigue crack growth under variable amplitude loading. Studying of fatigue crack growth rate and fatigue life calculation under spectrum loading is very important for the reliable life prediction of engineering structures. In this paper, a fatigue life prediction model under various load spectra, using the strain energy density factor approach and the plastic zone size near crack tip as main parameters in calculating effective strain energy density factor, has been proposed. The present model is validated with fatigue crack growth test data provided by Ray under various variable amplitude and spectrum loading in 7075-T6 and 2024-T3 aluminum alloy, respectively. Predictions of present model are compared with those of the state-space model, FASTRN and AFGROW codes. The results show that the predicted results agree well with the test data.