Perspirable skin: Thermal buckling achieved by complex functionally graded materials

A perspirable skin is a new design concept of thermal protection system that will autonomously reduce the surface temperature in many applications such as reentry and hypersonic vehicles. A unique design features an assembly of tiles, which buckles upon heating. Potentially, a large gap can be generated through this buckling action. These tiles will be assembled and shrink-fitted within an opening on the existing skin. To induce the buckling action, each tile needs to have a unique CTE variation, which causes thermal expansion radially and thermal shrinkage tangentially. This paper concentrates on the fabrication of these tiles made of complex functionally graded materials (FGMs), and presents our effort to design and fabricate these tiles.