Transient Thermal Analysis and Viscoplastic Damage Model for Life Prediction of Turbine Components

Abstract

This paper reports the process and computer methodology for a physicsbased 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 timeaccurate, coupled aerothermal computational fluid dynamics (CFD) with nonlinear deformation thermalstructural finite element model (FEM) with a slipbased constitutive model, evaluated at real engine characteristic mission times, and flight points for part life prediction. The methodology utilizes a fully coupled elasticviscoplastic model that was based on crystal morphology, and a semiempirical life prediction 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 threedimensional FEMs 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.