Advances in out-of-autoclave consolidation of thermoplastic composites

Cost-effective manufacturing of large and complex structures for aerospace applications is very promising yet not straightforward for thermoplastic composites. The currently accepted manufacturing technology for such structures is autoclave consolidation, which is expensive. Recent studies at the TPRC focused on different out-of-autoclave consolidation technologies, such as laser-assisted fiber placement with in-situ consolidation and a combination with secondary consolidation via stamp forming or vacuum-bag-only processing. The air evacuation during vacuum-bag-only consolidation was investigated, showing that the intra-ply diffusion and the presence of inter-ply air channels are important factors. The introduction of gaps between tapes during tape placement was investigated as a potential solution for improving the in-plane air evacuation for preforms with limited air inter-ply channels. It was shown that these channels can be produced with the fiber placement process, and that they result in good consolidation quality for the material system investigated in this paper.