CORNERSTONE RESEARCH GROUP INC — Department of Defense SBIR Phase I: N231-069

Description

The perceived objective is to generate a method that enables low-cost lightweight airframes produced in a way conducive to high- rate manufacturing. The production of air vehicles must rapidly increase in order to prepare for a war of attrition and increase the United States’ air superiority. As the desire for rapid development and production of composite air vehicles increases, the need for faster fabrication processes becomes more important. One of the more time-consuming elements of the aircraft fabrication process is the assembly of all the complex components required to create the air vehicle shape and structure. Typical aircraft assembly processes include individual skin and internal structure pieces that are mechanically fastened together or, in some cases, bonded together. The process for creating the provisions for fastening (typically hole drilling) and bonding, as well as the process for holding the pieces in the correct locations during assembly (use of assembly jigs), requires significant time and capital expense. In addition, these processes require inspection steps to ensure they were performed correctly. Ultimately, these labor- and capital-intensive processes increase the lead-time and cost of assembled aircraft structures. An alternate approach to reduce or eliminate these steps is desired to achieve goals of more rapid air vehicle development and production. Compression molding is a rapid composite forming process that forms and cures in minutes rather than hours, allows for a wide range of shapes and thickness, and allows for objects such as metal bosses to be imbedded into parts during forming. Typically used for compression molding is sheet molding compound (SMC), which is widely available in carbon and fiberglass options. This technology is proven to produce low-cost parts, with production part cost of under $200 per pound, not including NRE and tooling. This high-rate manufacturing process consists of rapidly cutting the SMC with a ply cutter, loading the material into the mold, closing the press and keeping it closed for 2 to 10 minutes, then removing the formed part from the mold to cool.