Manufacturing of a composite wing with internal structure in one cure cycle

Abstract

The need for faster and more accurate manufacturing methods for composite parts continues to grow. Co-curing composite structures can decrease manufacturing time by eliminating secondary operations such as grinding, jigging, bonding, and fastening while creating lighter and more accurate parts. As a demonstrator for co-curing techniques, a six-meter carbon fiber wing for a high-altitude and high-speed dynamically soaring unmanned aerial vehicle (UAV) was designed and manufactured in one cure cycle. Two wing-skin molds were created using low density tooling board, with the mold geometry directly machined into the material, reducing tool manufacturing time and cost. An aluminum insert was used to create a trailing edge cavity while maintaining a simple parting line of the wing tool. Three removable forms made of polystyrene foam inside of the wing cavity were used to position six internal webs and, after curing and removal of the forms, resulted in a hollow wing with internal webs. The resulting wings showed some defects in the wing skins but overall produced structurally sound parts. The method shows great potential for creating complex composite parts using only a single cure cycle with little finishing work and no secondary bonding, resulting in high precision at a relatively low cost.