Volume 20, Issue 6, 2011
Full Articles: MINIMIZING THICKNESS VARIATION IN THE VACUUM INFUSION (VI) PROCESS
Bekir Yenilmez, Talha Akyoll, Baris Caglar and E. Murat Sozer*
Koc University, Mechanical Engineering Department Rumelifeneri Yolu, Sariyer 34450, Istanbul, Turkey
* Author to whom correspondence should be addressed: Tel.:+90 212 3381582; Fax: +90 212 3381548; e-mail address:
Received 25 August 2011; accepted 23 December 2011
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 flow 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 flow and compaction model qualitatively verifi ed the pressure and thickness distributions
for both filling and post-filling stages.
Keywords:Fabrics, process monitoring, resin flow, thickness variation.