Design and manufacturing of a representative thermoplastic composite primary aerospace structure

The use of high performance thermoplastic composite structures in aerospace has seen a great increase in the past decade. Thermoplastic composites present many advantages over thermoset composites in terms of processing and performance, such as high toughness, high temperature performance, chemical resistance and low flammability. However, compared to thermoset matrices, the lack of material database and the limited knowledge available in the open literature regarding the manufacturing techniques have restrained their use to a relatively small number of composite structural applications. In this study, the design and the autoclave manufacturing of a PEEK/carbon hat-stiffened panel representative of an aerospace primary structure were investigated. Design and mechanical performances, including strength and stability issues, were first evaluated with finite element analysis and analytical methods. Process simulations were also performed to define the tooling material and geometry to be used, based on the evolution of the thermo-mechanical material properties during the autoclave process. For the manufacturing part, the stringers were first pre-shaped and consolidated in a press and then re-consolidated to the panel skin in the autoclave. The data gained from the manufacturing was used to validate the process simulation and the panel design. This project showed the autoclave process capability for manufacturing large, integrated and complex thermoplastic composite structures.