Method to estimate multiple permeability components from a single rectilinear experiment in liquid composite molding processes

Lugo, Jeffrey
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University of Delaware
Liquid Composite Molding (LCM) processes are useful in manufacturing high quality parts at low cost. To ensure this quality, modeling and simulation of the process should be performed before the part is manufactured. Predicting infusion and resin-impregnation will give the manufacturer an advantage when setting up the LCM process. It is essential, then, to evaluate accurately the permeability of individual system components such as flow enhancement media (distribution media) and multiple preform layups that is usually required as input to such simulation of resin flow. Extensive work has been devoted to developing various methods of this evaluation, with the majority of the work focusing on a single type of fabric characterization. In this work, a methodology is developed and validated to estimate the in-plane and transverse (through-thickness) permeability of the fabric, as well as permeability of the distribution media in the direction of the flow. An effective permeability for the combination of fabric and distribution media is also defined. The approach is based on tracking the resin flow-front during linear infusion along the top and the bottom surface over a sample representing several material layups (a segment of which includes the flow enhancement media). Analytic solution of flow progression is derived and used to characterize the permeability of all components/layups. The solution, the error due to the assumptions and approximations made and its limits of applicability are presented. A numerical technique using flow simulation results is utilized to execute a data correction algorithm to further improve experimental estimates.
Liquid composite molding , Permeability , Resin flow , Fabric characterization