Optical properties optimization of carbon fiber reinforced thermoplastic tapes by micro surface texturing for enhanced laser heating efficiency and in-situ consolidation quality during AFP process

Abstract

The laser-assisted automated fiber placement (L-AFP) process of carbon fiber-reinforced thermoplastic composites suffers from insufficient heating efficiency and in-situ consolidation quality caused by significant reflection on the tape surface. Here, we propose a novel strategy to increase the heating efficiency by refocusing the reflected light, initially scattered to the environment and wasted, onto the tapes for multiple and full absorptions. The method for laser concentration is first validated through light-tracing simulation. Then, three kinds of tapes with different micro textures on the surface are prepared by the hot-embossing process. The transverse V-grooved texture tapes and flat surface tapes absorb 25% more laser energy than the longitudinal V-grooved and commercial tapes due to the reduction in transverse scattering angle from 180° to 2.72°. This leads to a temperature increase of 130 °C at the nip point during the L-AFP process at the lay-down rate of 500 mm/s with 1 kW laser power. Improved in-situ consolidation quality leads to a significant increase in the flexural and shear strength of L-AFP-prepared carbon fiber reinforced polyetheretherketone (CF/PEEK) laminates, with a reduction in porosity to around 2%.