A New Energy-Based Uniaxial Fatigue Life Prediction Method for a Gas Turbine Engine Material

Abstract

A new energy-based fatigue life prediction framework for calculation of axial and bending fatigue life at various stress ratios has been developed. The purpose of the life prediction framework is to account for materials used in gas turbine engines, such as Titanium 6Al-4V, which experience an endurance stress limit as the number of cycles increase towards infinity. The work conducted to develop this energy-based framework consist of the following entities: (1) A new life prediction criterion for axial and bending fatigue at various stress ratios for Aluminum 6061-T6, (2) use of the previously developed improved uniaxial energy-based method to acquire fatigue life prior to endurance limit behavior [1], (3) and the incorporation of a statistical energy-based fatigue life calculation scheme to the uniaxial life criterion (the first entity of the framework), which is capable of constructing prediction intervals based on a specified percent confidence level. The exactitude of this work was verified by comparison between theoretical approximations and experimental results from recently acquired Al 606-T6 and Ti 6Al-4V data. The comparison shows very good agreement, thus validating the capability of the framework to produce accurate fatigue life predictions.