In resin transfer molding (RTM) a high permeability layer (HPL) is placed on top of the fiber mat lay-up to reduce mold filling time and increase the ultimate distance resin can be drawn into the mold. HPL’s are particularly useful in vacuum bag resin transfer molding (VBRTM), where driving pressures are relatively low. When compared to traditional closed mold RTM, VBRTM has the advantages of low capital costs and short start up time. The goal of the current research is to investigate how an HPL can be used to improve quality and process efficiency for parts of complex geometry made by both conventional and vacuum bag RTM. As a first step towards this goal, the effect of the HPL on the flow field has been studied through analysis, experiment and simulation. As expected, the use of the HPL creates a transverse (i.e., top-to-bottom) flow in the fiber mat, facilitating mold filling. The thickness of the HPL has been varied to determine the effects on the flow front. The experimental results validate the capability of the simulation to model two-dimensional flow in a porous medium with heterogeneous permeability.

Issue Section:
Research Papers
Topics:
Permeability, Resins, Transfer molding, Flow (Dynamics), Fibers, Simulation, Vacuum, Geometry, Porous materials
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