Session: 03-01-01: Advanced Manufacturing

Paper Number: 188064

188064 - Rapid Resistance Welding of Cf/peek Composites Using a Cnt/pei Heating Element 

High-performance thermoplastic composites (TPCs) show strong promise for aerospace and automotive applications due to their high toughness, potential for recycling, ease of repair, reduced reliance on adhesives and mechanical fasteners for joining, and essentially unlimited shelf life. However, reliable joining of TPC subcomponents remains challenging. Resistance welding is a promising technique owing to its rapid processing and ease of use. However, conventional metallic heating elements, such as metal meshes, act as foreign inclusions, introducing stress concentrations and corrosion risks within the joint. Conductive nanocomposite heating elements have been proposed to improve material compatibility; however, they often suffer from current leakage into electrically conductive laminates that are carbon fiber reinforced, which can reduce heating efficiency and limit process control. This study introduces a fully compatible resistance welding strategy that combines a carbon nanotube (CNT)/ polyetherimide PEI nanocomposite heating element with a neat PEI interlayer incorporated during laminate consolidation onto TPC plates, made from carbon fiber–reinforced polyether ether ketone (CF/PEEK). Sixteen-layer unidirectional CF/PEEK laminates were manufactured using the Vacuum Bag Only (VBO) technique, during which a thin, resin-rich PEI film was co-consolidated onto the CF/PEEK composite surface. During resistance welding, the neat PEI sides of the plates were placed in direct contact with the CNT/PEI heating element. The neat PEI interlayer serves a dual function. Electrically, it acts as a dielectric barrier that prevents current leakage from the heating element into the carbon fibers. It also enables fusion bonding at reduced processing temperatures or with faster welding times than PEEK, by exploiting the amorphous nature of PEI. Fabricated welded joints were evaluated using lap shear strength (LSS) testing. Effective welding was achieved even at 30 s, however, optimal welding duration of 90 s at a constant pressure of 0.8 MPa yielded a maximum SLS of 37.6 MPa, on par with the SLS of coupons joined in a hot press. Fractographic examination demonstrated a transition from ductile mixed-mode fracture to fiber-tear failure with increasing welding duration, indicating full interfacial consolidation, elimination of interfacial discontinuities, and load transfer governed by the intrinsic strength of the composite reinforcement. These results demonstrate the effectiveness of the proposed strategy for resistance welding of CF/PEEK composites.

Presenting Author: Yunus Emre Bozkurt Istanbul Technical University

Presenting Author Biography: Yunus Emre Bozkurt is a Ph.D. candidate in Materials Science and Engineering at Istanbul Technical University and a former visiting researcher at the University of California San Diego. He specializes in the fabrication and characterization of high-performance thermoplastic composites, with a primary focus on Polyetheretherketone (PEEK) and Polyetherimide (PEI). His research investigates the potential applications of thermoplastic blends and composites in aerospace structures, including the development of resistance welding techniques for carbon fiber-incorporated systems.