Analysis of sandwich TPS panel with functionally graded foam core by Galerkin method

The method of Fourier analysis is combined with the Galerkin method for solving the two-dimensional elasticity equations for a sandwich thermal protection system (TPS) insulation panel with foam core subjected to transverse loads. The variation of the Young’s modulus through the thickness is given by a polynomial in the thickness coordinate and the Poisson’s ratio is assumed to be constant. The Fourier series method is used to reduce the partial differential equations to a pair of ordinary differential equations, which are solved by using the Galerkin method. The method will be useful in analyzing functionally graded TPS structures with arbitrary variation of thermomechanical properties in the thickness direction. The analysis was also performed using sandwich plate theory. Significant differences were found in the results suggesting that the sandwich theory may not be suitable for the analysis of thick sandwich TPS panel.