Optical characterization of fiber-reinforced thermoplastic tapes for laser-based composite manufacturing

The optical properties of unidirectional (UD) fiber reinforced thermoplastic (FRTP) tapes were characterized to enable a better description of the heating phase in laser-based manufacturing process of FRTP composites. The tapes included PP-GF (glass-fiber) 45% fiber volume content (FVC), PVDF-CF (carbon-fiber) 45% FVC, PVDF-CF 60% FVC and PA12-CF 60% FVC. The transmittance of the tapes was found to be 0.00–0.2% whereas the reflectance was 9.8–11.8% corresponding to a refractive index of 1.91–2.05. The anisotropic reflectance measurements, as obtained through a gonioreflectometry, were used to fit the bidirectional reflectance distribution function (BRDF) for the first time. The obtained BRDF parameters σt and σf had a range of 0.1–0.18 and 0.006–0.015, respectively, for different tapes. Employing the new BRDF parameters empowers a more accurate prediction and optimization of the process settings of laser-based composite manufacturing. Laser-assisted tape placement/winding (LATP/LATW), anisotropic reflection, unidirectional tape (UD), bidirectional reflection modelling.