Flow Analysis with Fiber Preform Deformation During Compression Resin Transfer Molding
Date
2010
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
Compression resin transfer molding (CRTM) is an alternative solution to
conventional resin transfer molding processes. It offers the capability to produce net
shape composites with fast cycle times making it conducive for high volume
production. The resin flow during this process can be separated into three phases; (i)
metered amount of resin injection into a partially closed mold containing dry fiber
preform, (ii) closure of the mold until it is in contact with the fiber preform displacing
all the resin into the preform and (iii) further mold closure to the desired thickness of
the part compacting the preform and redistributing the resin. Understanding the flow
behavior in every phase is imperative for predictive process modeling that guarantees
full preform saturation within a given time and under specified force constraints.
In this thesis, the CRTM flow is modeled as a two dimensional flow in a
gradually deformed porous medium during all three phases. The governing equations
are formulated and coupled with the constitutive equations that describe the
deformation and permeability behavior. Due to the non-linear nature of coupled
system of equations, a numerical solution is developed that describes the flow front
progression and the preform deformation during the process. A non dimensional
analysis is conducted in which the applied force and initial gap size emerge as the
important process variables that influence the process cycle time. Limiting cases are
identified which reduce the flow to one dimensional flow for which a simplified
solution is developed. The results are verified using an experimental setup whichapplies a constant force to the preform in a transparent mold allowing one to track the
flow front.
This study quantifies the effect of preform deformation due to the fluid
pressure and should prove useful in applications that involve fluid impregnation in
deforming porous media.