PROOF OF CONCEPT FOR VACUUM BAG ONLY CONSOLIDATION OF BRAIDED THERMOPLASTIC FABRIC

This paper presents a pioneering approach to consolidate thermoplastic braided fabrics using a Vacuum Bag Only (VBO) process, demonstrating its potential to replace or augment thermoplastic tape placement via Automated Fiber Placement (AFP). Leveraging advanced thermoplastic carbon fiber prepreg from Teijin Carbon with braid converting from A&P Technology, VBO consolidation addresses higher rate Out of Autoclave (OoA) processing for applications requiring high mechanical properties and a high impact resistance while simplifying manufacturing workflows. The VBO consolidation process capitalizes on key material properties of thermoplastic materials and braided fabrics: drapability, the absence of tack and cold flow, no exothermic reactions or volatiles, and guaranteed air evacuation pathways regardless of part geometry. Two challenging parts have been produced to demonstrate VBO consolidation capability, a conical spinner fairing and a large area curved skin. Both were successfully fabricated using braided fabric made from IMS65 P12 carbon fiber with 34% PAEK content. The parts showed excellent consolidation quality under VBO conditions, with a 30 to50 minute hold at temperatures about 390°C. Parts were validated through visual and C-scan NDI characterization. In addition, compression molded panels made from the same braid fabric exhibited mechanical properties equivalent to qualified carbon fiber with PAEK tape materials from Toray and Victrex, NMS 125 and NMS 122. The novel use of VBO for thermoplastic fabrics, particularly for large parts, represents a significant step change in thermoplastic composite manufacturing and, to the best of our knowledge, marks the first published instance of VBO consolidation with thermoplastic fabrics.