SBIR-STTR Award

Currently aircraft composite and metal structures are joined by fastening them in place using riveted or bolted joints. Although fastened joints largely avoid concerns associated with thermally induced stresses and strains from CTE mismatches, such designs add weight, manufacturing complexity and cost to the design. Recent advances have given rise to new opportunities to increase the integrity and performance of metal to composite joints. This effort will investigate these new technologies for their application to hybrid joining concepts. This program will design, fabricate and test specimens from one technology, which benefits from newly developed metal processing capabilities. Two other technologies will also be analyzed to determine their merit and feasibility. Design optimization will be accomplished on all three concepts by first performing an analysis of the joints using the analytical tools developed under the Composites Affordability Initiative (CAI). Optimized joints representing the most promising technology will then be fabricated and mechanically tested to validate the new joining concept and model and to demonstrate and quantify their technical feasibility. Successful completion of this program will result in new joining methods that will be used by the various DoD contractors on potentially numerous new vehicles

Currently aircraft composite and metal structures are joined by fastening them in place using riveted or bolted joints. Although fastened joints largely avoid concerns associated with thermally induced stresses and strains from CTE mismatches, such designs add weight, manufacturing complexity and cost to the design. Recent advances have given rise to opportunities to increase the integrity and performance of metal to composite joints. Specifically this effort will investigate CoMeld and Cold Spray technologies for their application to hybrid joining concepts. This program will focus on these new technologies for formation of in-situ fasteners for joining composites and metals. Initially coupon level tests will be performed using a design of experiments and the results will be used to populate the analysis database. In addition, preliminary fatigue and corrosion performance questions for these new joints will be answered. The data will be used for down-selecting the ìbestî joining technique, which will subsequently be verified through subcomponent testing. The results will be used to conduct a cost benefit analysis to help implementation into LM-Aero applications. Successful completion of this program will result in the development of new joining methods that can be used by the various DoD contractors on numerous next generation aircraft.

Keywords:
Hybrid Joints, In-Situ Fasteners, Composites, Metals, Co-Meld, Cold Spray, Bonding