EFFECT OF STRESS RATIO ON FATIGUE CRACK GROWTH RATE

Despite all the efforts made trough the years, lifetime estimation of components subjected with variable amplitude loading is still a major problem for engineering calculation. Introduction of risk-based methods and damage tolerance imposed ample studies on material mechanical properties, especially on fatigue crack growth. Knowing that fatigue crack growth rate is strongly influenced by the R- ratio, a series of models, that explain the stress ratio effect on fatigue crack growth rate, are proposed. Consequently, the purpose of our paper is to present a calculation mode of fatigue crack growth rate, taking into consideration also the effect of the R-ratio.