This Small Business Innovation Research Phase I project seeks to develop materials and manufacturing processes that enable aerospace composite materials to be produced without an autoclave. To ensure the best material quality and reliability, aerospace composites are processed inside autoclaves that combine heat and pressure to fully bond multi-layered composites. Autoclaves that can accommodate aircraft fuselages and wings now exist. The capital costs, labor costs, and manufacturing times associated with autoclave processing are significant but are a necessary evil to ensure composite quality. A large opportunity exists for Out Of Autoclave (OOA) technology to reduce costs and streamline composite manufacturing operations. The current OOA focus of industry is to develop new resin/fabric systems that can be processed OOA but still yield suitable performance. A better approach to achieve broad-based OOA manufacturing is to compatibilize existing resin/fabric systems. This goal may be achieved through a combination of new tooling materials and manufacturing processes that can self-pressurize and consolidate composites. The results of the Phase I effort will demonstrate a true OOA technique that allows autoclave equivalent composite properties to be achieved in any existing resin/fabric system without the use of autoclave.
The broader impact/commercial potential of this project is to provide the composites industry with an OOA solution that is resin independent. The use of advanced fiber reinforced composites in aircraft has become a necessity to achieve higher performance and greater fuel efficiencies. Boeing's 787 and Airbus' A350 are two such aircraft that exemplify the push to increase composite content above 50% by weight. A large opportunity exists for OOA technology to reduce costs and streamline composite manufacturing operations. The OOA technology developed in Phase I will have a large impact on the composites industry through cost reduction and manufacturing efficiency gains. It will allow a broader manufacturing base to produce autoclave-like parts. Society will see benefits through the broader use of fuel-efficient composites in air- and land-based vehicles. This effort will also foster collaboration between small business and large aerospace manufacturers as well as offer undergraduate and high school students an opportunity to work on the project.
The overall objective of this Phase I SBIR project was to demonstrate a new composite manufacturing method that allows conventional pre-pregs to be used Out of Autoclave (OOA) while achieving autoclave quality. The availability of this OOA enabling mandrel technology would reduce the costs and manufacturing bottlenecks associated with autoclave cycles. The specific technical objectives for Phase I were to develop a soluble expanding mandrel, engineer it to meet specific resin requirements, meet or exceed autoclave produced composite, and to produce a commercially relevant composite geometry using the system Each of the technical objectives was met during this effort. An initial expanding mandrel formulation was created referred to as ClaveCore. The ClaveCore mandrel material was designed to target a 280°F cure epoxy/E-glass pre-preg system. Time-Temperature-Pressurization behavior was characterized and compared favorably against the recommended autoclave curing cycle. Manufacturing variables were indentified and investigated to determine their effect on the production of high quality composite components. Test specimens were manufactured from the target pre-preg system using ClaveCore and compared against ones produced via traditional autoclave. The results showed equal or better tensile strengths and pore volume fractions. A prototyping demonstration was conducted on an aircraft air duct geometry that validated the technology’s feasibility to produce a complex component while also significantly reducing costs. Current high performance composites require the application of both heat and pressure via an autoclave to ensure a high quality lamination. Autoclaves are expensive to purchase and to operate so their use is typically limited to specialized composite manufacturers. The developed technology has excellent potential to eliminate the autoclave requirement without sacrificing quality or cost. ClaveCore materials will contribute to maintaining American manufacturing leadership and promote composite material technology by decreasing costs and improving competition. Potential applications include aerospace air ducts, structural components, aerodynamic surfaces, and performance sporting goods. Future impacts on society may include an improved manufacturing base, more fuel efficient aircraft, and lower cost composite components. Undergraduate students have been involved in this project to help train the next generation of engineers.
