Understanding processing parameter effects for carbon fibre reinforced thermoplastic composites manufactured by laser-assisted automated fibre placement (AFP)

In this study, experimental investigations were performed to gain insights into the processing parameter effects of laser-assisted automated fibre placement (AFP) on the mechanical properties of carbon fibre (CF)/polyphenylene sulphide (PPS) composites from the perspective of void content and crystallinity. First, thermal characterisation was carried out to obtain the processing window for the PPS/CF composites. The temperature histories at the nip point during an AFP process were measured using an in-house temperature measurement system and the desired ranges of laser power and placement rate were determined based on the measured temperatures. The placement rate was ranging from 6 to 60 m/min, and the range of the used laser power was 1–6 kW. Then, the effects of tool temperature ranging from 30 to 120 °C on the interlaminar shear strength and compression strength of the CF/PPS composites were examined. It was found that the interlaminar void content dominated the mechanical properties of the composite rather than the crystallinity. Finally, the composites produced by the AFP were further treated by an autoclave. It was shown that the interlaminar shear strength of the composites was significantly improved after the autoclave post-consolidation treatment due to the reduction in void content and the improvement of crystallinity. The interlaminar shear strength of the composites after the autoclave treatment was found to be independent of the placement rate, indicating elimination of the AFP thermal history due to sufficient heating and compaction time in the autoclave.