Session: 03-01-01: Advanced Manufacturing

Paper Number: 195939

195939 - Manufacturing and Assembly of Thermoplastic Composites for High-Rate, Low-Cost Structures 

Thermoplastic composites (TPCs) are increasingly attractive for next-generation aerospace structures because they offer not only high performance and damage tolerance, but also the unique ability to be fusion bonded for assembly, repair, and reconfiguration. However, their broader adoption remains limited by the high processing temperatures, long cycle times, and substantial energy demands associated with conventional manufacturing and joining methods. This talk presents a unified approach to the rapid, low-cost, low-temperature, out-of-autoclave manufacturing and assembly of high-performance thermoplastic composites. I begin by discussing the science of bond development in fast-cycle TPC processing, showing how thermal history, polymer morphology, and fiber architecture interact to govern interlaminar healing, fracture toughness, and structural integrity. Building on this framework, I introduce an out-of-autoclave amorphous/crystalline laminate architecture based on carbon fiber/polyether-ether-ketone (CF/PEEK) with thin polyetherimide (PEI) interlayers. Because PEI is amorphous and miscible with PEEK, these interlayers enable rapid interfacial healing at temperatures substantially below the typical melting-based processing window of PEEK, preserving crystallinity while reducing thermal exposure, distortion, and energy consumption. This architecture enables vacuum-bag-only processing of aerospace-quality laminates at substantially higher throughput and far lower energy use than conventional approaches, offering a practical route to scalable, high-rate manufacturing. I then show how the same materials philosophy extends naturally from manufacturing to assembly. In particular, I present amorphous-interface welding strategies in which PEI-rich bond lines are pre-bonded to CF/PEEK adherends, enabling efficient joining during subsequent induction or resistive welding without the need for conventional high-temperature melt-dominated interfaces. I also discuss a new class of polymer-based nanocomposite susceptors, formed by incorporating tailored nanomaterials into a fully miscible amorphous polymer, that can be designed for resistive, induction, or RF heating. These susceptors enable localized and energy-efficient heating, reduced peak processing temperatures, improved process robustness, and strong, damage-tolerant joints while reducing the risk of thermal degradation and preserving the crystallinity of the parent composite. Beyond joining, they also create opportunities for multifunctionality, including controlled disassembly for repair or rework and real-time bond-quality monitoring. Experimental results on CF/PEEK systems illustrate how low-temperature bond-line design can expand the processing window, increase throughput, and provide a common foundation for both manufacturing and assembly. Together, these advances point to a scalable pathway for low-cost, energy-efficient, and high-rate out-of-autoclave processing of thermoplastic composite structures for aerospace and other demanding applications.

Presenting Author: Mehran Tehrani University of California San Diego

Presenting Author Biography: Mehran Tehrani is an Associate Professor of Structural and Materials Engineering at the University of California San Diego (UCSD). He is an ASME Fellow and holds the Callaway Golf Endowed Chair at UCSD. His research focuses on advanced multifunctional composites at the intersection of advanced manufacturing, materials science, and mechanics, with an emphasis on energy-efficient, lightweight structures. He has published over 100 journal and conference papers and has received several awards for research and teaching, including the Composites Part B Mid-Career Global Excellence in Composites Engineering Award, the NASA Early Stage Innovations Award, the NSF CAREER Award, the ONR Young Investigator Program (YIP) Award, and the Air Force Research Laboratory Summer Faculty Fellowship.