Prediction of the low cycle fatigue regime of the S–N curve with application to an aluminium alloy

Engineering estimates for the prediction of fatigue life is an important consideration at the design stage of components. Conventional approach of dimensioning against cyclic loading consists of comparing the stress amplitudes against the life time. Similarly, when a component is under high loading, a strain-life methodology is adopted. In both cases, extensive experimental efforts are required for obtaining the stress-life or strain-life curves. Therefore, it is important to develop a methodology for obtaining the fatigue life of a material to obtain a basic fatigue life data for design engineers. This study focuses on the fatigue life of a material in the region of low cycle fatigue. A method is proposed for obtaining an estimate for the fatigue life of material under high loading from the results of the high cycle fatigue and static properties of the material within the stress-based diagram. The concept is applied to a wrought aluminium alloy typically used for cryogenic applications.