Prestressed Cryopipe for Rocket Engine Lines/Ducts

This stress-profiling research is an important component for weight savings on the MDA funded Airborne Laser. Both deployable and airborne systems are candidates. The objectives are to cut piping weight and cost by half.Prestressed composite cryogenic piping (US Patent 6,325,108) adds a layer of circumferential prestress to cured PMC pipe. Prestress induces compression in the interior surface to prevent delamination and tension micro cracks. This was observed as abyproduct of prior cryogenic testing and further demonstrated in Phase I. Most polymers exhibit increased stiffness at cryogenic temperatures. Stiffness limits the polymer's ability to distribute loads to the high-modulus fibers. For compositesexperiencing multiple thermal shocks and chemical attack, prestress is the key to structural integrity and longevity. Beyond the patented cryopipe this proposal includes supportive innovations in high compression, low creep, chemically resistant and lowpermeable polymers.Phase II will model, fabricate, cure, prestress and comparatively test cylindrical composite sections in antagonistic chemical and cyclical cryogenic environments. Both commercial and aerospace qualified materials will be used. A foil liner system will bestudied. Design software will provide structured accessibility to the stress-profiling technique and facilitate technology transfer for Phase III flight tests.