Estimation of Thermal Diffusivity Profile in an FGM from Temperature Responses at the Front and Rear Surfaces

Abstract

Temperature response in a functionally graded material (FGM), subjected to transient heating. is investigated in order to estimate thermal diffusivity profile in the FGM, relevant to qualification of FGMs as advanced heat-shielding/structural materials in future space applications. An attempt has been made to use temperature response at the front surface in obtaining a distribution parameter, which gives the thermal diffusivity profile in FGM when a distribution of the thermal diffusivity can be expressed by an exponential function. Following a procedure in the literature, an explicit relation is obtained between the distribution parameter and thermal diffusivity at the front surface. Although it is approximate, it has turned out to be a fair representation for the dependence of the temperature response on the thermal diffusivity. In order to further examine usefulness of this relation, a comparisons has been made between the assumed and estimated thermal diffusivity profiles. In this examination, a distribution parameter near the front surface is determined by the thermal diffusivity at the front surface; that near the rear surface is determined by the thermal diffusivity at the rear surface, A fair agreement between these profiles is demonstrated, as far as the trend and approximate magnitude are concerned.