Microvoid Formation in Fiber Tows with Non-Uniformly Spaced Fibers

Abstract

Liquid composite molding is a common manufacturing method to fabricate complex and net shape composite parts in which a liquid resin is introduced into a dry fibrous preform. The fiber preforms usually contain fiber tows and resin impregnation is driven by an applied pressure and capillary forces. The fiber tows are usually less permeable than the regions in between them hence the resin will typically flow around the fiber tows at much faster rate than into them. This paper predicts microbubble formation in fiber tows with non-uniformly spaced fibers and the dissolution of the microbubbles before the resin cures. Any microbubbles trapped within the tow after curing will be microvoids in the final composite part. A parametric study is conducted to determine the influence of fiber packing and manufacturing process parameters on microvoid formation within tows.