Minimizing thickness variation in the vacuum infusion (VI) process

Abstract

In the Vacuum Infusion (VI) process, the thickness of a composite part changes as the compaction pressure on the vacuum bag and reinforcing fibre preform changes. Pressure and thickness were monitored along a 1D resin fl ow using pressure transducers and non-contact laser displacement sensors. To decrease the thickness variation, control actions were taken by adjusting the injection conditions, such as opening/closing gates/vents, changing pressure of them in the post-mold filling stage and bleeding out the excess resin. The control actions were taken based on an available compaction/decompaction database for the fabric type used. Compared to the case study with no control action other than bleeding, a better job was done in the controlled case study by decreasing the maximum thickness variation from 5.44% to 0.39%. A coupled fl ow and compaction model qualitatively verified the pressure and thickness distributions for both filling and post-filling stages.