QUANTITATIVE APPROACH TO DETERMINE BLEEDING TIME FOR COMPLETE TOW SATURATION

摘要

Liquid Composite Molding (LCM) processes use fiber mats made up of fiber tows whichrnare woven, braided, or stitched together. The fiber tows that are woven into fiber matsrnconsist of thousands of single strands of individual fibers. The impregnation of resin intornthese fiber tows occurs at a much slower rate as compared to the spaces between the fiberrntows due to the dual scale nature of these fabrics. Hence, the fiber tows are notrncompletely saturated when the resin reaches the vent location. To ensure completernsaturation of the fiber tows, the resin is allowed to bleed out of the vent for a long periodrnof time based on intuition and experience. This bleeding time will vary with thernproperties of the fabric, fiber volume fraction, resin viscosity and geometricalrncharacteristics of the mold and the vent. A numerical simulation is coupled with an outletrnmodeling feature to calculate the bleeding time for complete saturation of the fiber tows.rnThis study also introduces the non-dimensional material and geometric parameters andrntheir influence on the bleeding time.