Transient Thermal Analysis and Visco-Plastic Damage Model for Life Prediction of Turbine Components

This paper reports the process and computer methodology for a physics-based prediction of overall deformation and local failure modes in cooled turbine airfoils, blade outer air seals, and other turbomachinery parts operating in severe high temperature and high stress environments. The computational analysis work incorporated time-accurate, coupled aerothermal CFD with non-linear deformation thermal-structural FEM with a slip-based constitutive model, evaluated at real engine characteristic mission times and flight points for part life prediction. The methodology utilizes a fully-coupled elastic-viscoplastic model that was based on crystal morphology, and a semi-empirical lifing model introduced the use of dissipated energy to estimate the remaining part life in terms of cycles to failure. The method was effective for use with three-dimensional finite element models of realistic turbine airfoils using commercial finite element applications. The computationally predicted part life was calibrated and verified against test data for deformation and crack growth.