A Thermal Damage-Heat Conduction Coupled Model of Ceramic-Metal Functionally Graded Materials

Abstract

The coupling/interaction between the thermal damage and heat conduction of ceramic-metal FGMs under thermal shock and cyclic thermal loading is an important phenomenon. A theoretical model on the coupling phenomenon is developed to examine, quantitatively, the relationship between the thermal shock damage and effective thermal conductivity. The model is investigated with an effective medium method characterized by a self-consistent micromechanics. The thermal damage is treated as randomly distributed, penny-shaped microcracks. The damage effect is accounted for by introducing a crack density parameter. The effective thermal conductivity of the FGM interlayers is derived in terms of the model and connected with the crack density parameter. The model is verified by a concrete example and provides a new, useful method for the thermal damage evaluation of the materials.