Response of actively cooled metal foam sandwich panels exposed to thermal loading

In this paper, experimental and analytical results for the thermomechanical response of actively cooled metal foam sandwich panels are presented. With a favorable strength-to-weight ratio and a high specific internal surface Area, sandwich panels with metal foam cores are proposed for actively cooled load-bearing components in aerospace thermal protection system applications. First, inconel foam sandwich panels are subjected, via experimental means, to through-the-thickness thermal gradients, defined by fixed temperature conditions on opposite face sheets. With clamped boundary conditions, provided through a test fixture designed to minimize the common conflict of thermal and mechanical boundary conditions in experimental apparatus, the metal foam sandwich panels exhibit out-of-plane bending deformation. The thermomechanical deformation within the panel is then mitigated through active cooling, achieved by pumping compressed air through the metal foam core. Subsequently, the experimental measurements are used to develop a sequentially coupled thermomechanical finite element model. Central to the numerical characterization of metal foam sandwich panels is an understanding of the response of metal foam under shear loading. The material model for the foam is taken from a series of experimental measurements of the shear response of metal foam, providing density-dependent relationships for material stiffness and strength. The numerical model provides a strain-temperature history for metal foam sandwich panels under through-the-thickness thermal gradients. The results are shown to agree with the experimental measurements.