Manufacturing of a curved thermoplastic fuselage demonstrator with out-of-autoclave and welding technologies

Abstract

This study focuses on manufacturing processes of fiber reinforced thermoplastic fuselages. To demonstrate the technologies a part of a single curved fuselage section is manufactured. The primary components of a fuselage are the skin and its stiffening elements. In an integral design the stiffening elements include stringers, frames and cleats. The composite material for all investigated components is carbon fiber reinforced low melt polyaryletherketone (CF LM-PAEK). In this scenario the curved skin is manufactured by a vacuum consolidation process. The thermoformed z-shaped stringers are co-consolidated simultaneously with the skin consolidation. For the integration of frames and cleats static resistance welding is performed. First the frames are welded to the skin. Afterwards the cleat-frame joint is carried out followed by the welding process for the cleat-stringer joint. Using an out-of-autoclave oven process, the laminate consolidation up to 12 mm in thickness is validated. The demonstrated co-consolidation of the stringers leads to a continuous interface between stringers and skin. The specific resistance welding process is validated by single lap shear tests and an out of plane L-pull test. Both the consolidation including co-consolidation as well as the weld zones are inspected via phased array ultrasonic scans. Through combining these technological developments, the maturation level of thermoplastic component production increases. Thus, making a step toward the application of these technologies in the modern aerospace industry.