In-situ infrared annealing for laser-assisted automated fiber placement to enhance interlaminar properties without sacrificing laydown efficiency

Laser-assisted automated fiber placement (LAFP) in-situ consolidation (ISC) of thermoplastic composites suffers from poor interlaminar bonding. Repass treatment improves interlaminar bonding but sacrifices laydown efficiency. Here we propose an in-situ infrared annealing (IIA) strategy that combines infrared heat treatment with a second pressure roller immediately following the LAFP ISC process. This approach causes repeated interlaminar melting and slower cooling, reducing the porosity by 57.9% and increasing crystallinity by 89.2% compared to LAFP-manufactured carbon fiber-reinforced polyether-ether-ketone composites. Moreover, it completes the crystallization process with only a single placement rather than multiple placements by repass treatment. Interlaminar shear strength and mode I interlaminar fracture toughness are improved by 239.7% and 292.4%, respectively. These improvements are comparable to those achieved by repass treatment with a near-infrared laser. Overall, the IIA strategy offers a promising alternative to traditional post-consolidation processes while maintaining laydown efficiency.