SBIR-STTR Award

The conversion of alloy rocket engine ducts and lines to lighter, polymer composites raises the issues of cost effective joining/assembly for cryogenic operations. Dynamic Polymer Composite (DPC) connectors use the release of circumferential prestress to clamp cylindrical lines, ducts, and valves with forces as strong as the members themselves. For cryogenic piping, DPC connectors eliminate flanges, optimize component prefabrication, simplify assembly, and connect dissimilar materials. By varying the design, an axial expansion joint results that eliminates heavy, expensive alloy bellows. DPC connectors have been validated for airframes under an AF SBIR. These cryogenic connectors are two of seven, patented/proprietary DPC technologies. Together these make flange-less assembly of light-weight composite piping practical and cost effective, current BMDO goals. Using space qualified materials, Phase I will model, fabricate, and evaluate fixed and expansion DPC cryogenic connectors against equivalent flanged and bellows members. Phase II will develop and test prototype rocket engine sections connected by DPCs in a cyclical, cryogenic environment in preparation for Phase III contractor flight testing.Anticipated Benefits/Commercial Applications: A large composite pipe producer is a commercial partner for use in cryogenic process plants and oil/gas fields; $300,000 committed. Eight market segments have a potential of $200 million a year. The EELV has $6.2 billion in orders.

This Phase II research eill remove the two major barriers to converting metal alloy rocket engine lines and ducts to polymer matrix composites (PMC). These barriers are (1) unreliable composite flange joints, and (2) heavy, expensive metal alloy bellows. The objectives are to cut both launch weight and cost by half. Dynamic Polymer Composite (DPC) connectors clamp fixed pipe joints with a large prestress when heated. They eliminate flanged joints adn join dissimilar materials with a smooth stress flow that is stronger than the pipe itself. DPC expansion joints replace alloy bellows. In Phase I both were validated by actual cryogenic pressure tests using prototypes not optimize for low temperature. Prestress was found to eliminate cryo delamination. Fixed joints were tested to 4,500 psi. Expansion joints demonstrated an axial travel of three inches (75mm). Using existing space quailified materials, Phase II will develop and cryo test a series of DPC connections designed and scaled for one of the seven current rocket engines in a cyclical, cryogenic enviroment. Test and modeling data will be integrated for transfer of the technology to contractors in preparation for PhaseIII flight-testing. A large composite pipe producer is a commercial partener for use in oil and gas fields. $300,000 has been committed. Eight market segements with a potential of $200 milliona year have been identified. Alloy rocket fuel systems are $1.6 billion a year worldwide.

Keywords:
Cryopipe, Cryogenics, Connector, Rocket, Composites, Liquid Fuel, Prestress