A New Finite Element for Gas Turbine Engine Fatigue Life Prediction

Abstract

An energy-based fatigue life prediction framework was previously developed by the authors [1–4] for prediction of axial and bending fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In this study, the energy expressions that construct the new constitutive law is integrated into minimum potential energy formulation to develop a new finite element for fatigue life prediction. The comparison of Finite element method (FEM) results to existing experimental fatigue data, verifies the new finite element method for fatigue life prediction. The final output of this finite element analysis is in the form of number of cycles to failure for each element in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure for each element in gas turbine engine structural components. The performance of the fatigue finite element is demonstrated by the fatigue life predictions from 6061-T6 aluminum and Ti-6Al-4V. Results are compared with experimental results and analytical predictions [1].