Optimum Material Composition for Minimizing the Stress Intensity Factor of Edge Crack in Thick-Walled FGM Circular Pipes Under Thermomechanical Loading

Abstract

This paper deals with the optimization problem of material composition for minimizing the stress intensity factor of radial edge crack in thick-walled functionally graded material (FGM) circular pipes under steady-state thermomechanical loading. Homogenizing the FGM circular pipes by simulating the inhomogeneity of thermal conductivity by a distribution of equivalent eigentemperature gradient and the inhomogeneity of Young's modulus and Poisson's ratio by a distribution of equivalent eigenstrain, we present an approximation method to obtain the stress intensity factor of radial edge crack in the FGM circular pipes. The optimum material composition for minimizing the stress intensity factor of radial edge crack is determined using a nonlinear mathematical programming method. Numerical results obtained for a thick-walled TiC/Al₂O₃ FGM circular pipe reveal that it is possible to decrease remarkably the stress intensity factor of radial edge crack by setting the optimum material composition profile.