Thermal force and moment determination of an integrated thermal protection system

This paper is concerned with homogenization of a corrugated-core sandwich panel, which is a candidate structure for integral thermal protection systems for space vehicles. The focus was on determination of thermal stresses in the face sheets and the web caused by through-the-thickness temperature variation. A micromechanical method was developed to homogenize the sandwich panel as an equivalent orthotropic plate and calculate the equivalent thermal forces and moments for a given temperature distribution. The same method was again used to calculate the stresses in the face sheets and the core. The method was demonstrated by calculating stresses in a sandwich panel subjected to a temperature distribution described by a quartic polynomial in the thickness direction. Both constrained and unconstrained boundary conditions were considered. In the constrained case the plate boundaries are constrained such that there are no deformations in the macroscale sense. The unconstrained case assumes that there are no force and moment resultants in the macroscale. The results for stresses are compared with that from a three-dimensional finite element analysis of the representative volume element of the sandwich structure, and the comparison was found to be within 5% difference. The micromechanical analysis, which is less time consuming, will be useful in the design and optimization of integral thermal protection system structures.