Laser-assisted automated tape laying: Effects of placement rate and heated tooling on layer bonding and tensile properties

This paper investigates the processing parameters placement rate and tooling temperature of laser-assisted automated tape laying (ATL). Plates with carbon fiber-reinforced polyether ether ketone (CF/PEEK) were produced at 6 m/min, 9 m/min and 18 m/min, and 23°C and 250°C tooling temperature, respectively. Correlations of processing conditions with micrographs, void content, thickness, the degree of crystallinity and the shear strength of the compression shear test, including a fractographic analysis, were derived. Processing conditions that increase the degree of crystallinity were only found to improve the compression shear strength at 6 m/min placement rates, primarily due to a void content below 3.4 % and degree of crystallinity above 26 %. The fractographic analysis derived from the compression shear test revealed a strong correlation between the degree of crystallinity and the size of ductile drawings. In contrast, the transverse tensile test showed no influences on the ATL processing conditions, whereas the tensile strength in fiber direction decreased by 11 % from a placement rate of 6 m/min to 18 m/min. ATL with a 250°C tooling temperature increased the strengths by 14 % compared to those at room temperature. A further tensile strength improvement of 0° and 90° to 1754 MPa and 75 MPa was obtained by a subsequent out-of-autoclave consolidation using vacuum bagging.