Effect of Temperature and Crack Tip Velocity on the Crack Growth in Functionally Graded Materials

The stress-fields near the crack tip for mixed-mode thermo-mechanical loading in functionally graded material (FGM) are developed using displacement potentials in conjugation with an asymptotic approach. The shear modulus, mass density and coefficient of thermal expansion of the FGM are assumed to vary exponentially along the gradation direction. Using insulated crack face boundary condition and steady state heat conduction assumption, the temperature field near to the crack tip is developed. By incorporating the developed temperature field equations with the displacement potentials, asymptotic thermo-mechanical stress field equations are derived. Finally, utilizing the minimum strain energy density criterion and the maximum circumferential stress criterion, the crack growth direction for various crack-tip speeds, non-homogeneity coefficients and temperature fields are determined.