MATERIAL SELECTION CONSIDERATIONS FOR THERMOPLASTIC COMPOSITE AIRCRAFT STRUCTURES

For structure development programs, composite material selection is often based on mechanical properties, and for aircraft structure design, “notched” properties are commonly used in order to account for degradation caused by issues such as unseen impact damage. Compared to conventional thermoset composites, the higher toughness of thermoplastic matrices offers potential to mitigate some of these degradation effects but there is limited published data available on the mechanical properties of thermoplastic composites. To support an aircraft structure development program with Supernal LLC, a screening investigation was undertaken to assess notched properties for four Teijin Carbon America fiber-reinforced thermoplastic materials: Polyphenylene Sulfide (PPS) and Polyetheretherketone (PEEK), each in fabric and unidirectional forms. For each material quasi-isotropic laminates were manufactured from which specimens were tested in accordance with ASTM D6484 Open-Hole Compression (OHC) and ASTM D5766 Open-Hole Tension (OHT), to gather performance data to support a material selection decision. Information on material pricing in production quantities was also gathered to support decision-making. The results of the mechanical testing effort are provided along with important lessons learned related to laminate manufacturing, specimen preparation, and testing. Conclusions regarding the relative performance and comparative price of the candidate materials are provided.