Thermoset Prepreg Compaction during Automated Fiber Placement and Vacuum Debulking

Abstract

Automated Fiber Placement (AFP) is a well-established process in aerospace manufacturing with advantages regarding deposition accuracy and flexibility, reproducibility and potential lay-up rate compared to manual lay-up. Process parameters are typically optimized regarding deposition quality and deposition rate not taking into account ancillary processes like vacuum debulking with an influence on the overall process efficiency.Goal of this research is a consideration of the complete process chain from deposition to autoclave curing including all capabilities of the AFP process with defined process parameters. Therefore, this study investigates the influence and interrelation of the AFP and vacuum debulking parameters on laminate compaction. The experiments contained a systematic variation of the AFP process parameters deposition rate, processing temperature and compaction force as well as the vacuum debulking frequency. The resulting lay-up compaction was analyzed using an optical triangulation scanner for contactless thickness measurements at different plies, before and after debulking as well as before and after autoclave curing. Dominating effects were found for process temperature and debulking frequency. Interdependencies between many parameters display the complexity of the overall process and its analysis. It is shown that a replacement of a majority of the effect of debulking can be possible with an adjustment of the heat input during AFP. This allows a parameter optimization achieving a higher overall process efficiency.