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 which are woven, braided, or stitched together. The fiber tows that are woven into fiber mats consist of thousands of single strands of individual fibers. The impregnation of resin into these fiber tows occurs at a much slower rate as compared to the spaces between the fiber tows due to the dual scale nature of these fabrics. Hence, the fiber tows are not completely saturated when the resin reaches the vent location. To ensure complete saturation of the fiber tows, the resin is allowed to bleed out of the vent for a long period of time based on intuition and experience. This bleeding time will vary with the properties of the fabric, fiber volume fraction, resin viscosity and geometrical characteristics of the mold and the vent. A numerical simulation is coupled with an outlet modeling feature to calculate the bleeding time for complete saturation of the fiber tows. This study also introduces the non-dimensional material and geometric parameters and their influence on the bleeding time.