Design and Fabrication of CFRP Interstage Attach Fitting for Launch Vehicles

Lattice structures that are made of carbon-fiber-reinforced plastics (CFRP) have been commonly used for interstage structures in launch vehicles because of their high axial compressive strength-to-weight ratio. The purpose of this research is to investigate the failure behavior of filament wound lattice structures to demonstrate that these structures can be fabricated and formed precisely and automatically. For the failure modes, the general buckling as a shell and excessive stress are considered. Various types of lattice shells under axial compressive loads are presented, and the optimal constraint with the highest compressive failure load is found. The main emphasis is placed on the effects of geometrical configuration of the structure and the manufacturing process. The main geometrical characteristics that affect failure are the winding pattern, winding angle, and the slenderness of the members. The primary advantage of a filament wound lattice structure is that fibers are wound continuously and aligned with the load direction. The manufacturing process includes automated winding, winding path control, bridging effects, and the winding tension force. It is shown that these structures can be constructed by filament winding, that the process can be automated, and that the manufacturing cost can be reduced.