The Role of Transverse Flow in Co-Injection Resin Transfer Molding

Report No. ARL-TR-2135
Authors: Fink, Bruce K.; Gillio, Emanuele F.; Advani, Surresh G.; Gillespie, John W., Jr.
Date/Pages: December 1999; 39 pages
Note: Prepared in cooperation with University of Delaware, Newark, DE.
Abstract: A co-injection resin transfer molding (CIRTM) process has been developed at the U.S. Army Research Laboratory (ARL) in collaboration with the University of Delaware. It enables two or more resins to be simultaneously injected into a mold filled with a stationary fiber preform. This process allows for the manufacturing of cocured multilayer multiresin structures in a single processing step. A separation layer is used to provide resin compatibility during cure and to control resin mixing. In this study, scaling issues relating the role of transverse permeability in resin mixing are investigated. This report presents two different approaches taken to understand the causes of transverse flow and to quantify the amount of transverse flow. The first approach is a one-dimensional (1-D) model, which explains the important parameters that govern the flow in CIRTM. The second approach is based on an existing finite element code, which is modified to allow for the injection of multiple resins. The total amount of transverse flow was quantified using the finite element code. This research shows that he CIRTM process requires a totally impermeable separation layer if CIRTM is used to manufacture large parts and/or if the resins injected have significantly different viscosities.
Distribution: Approved for public release
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Last Update / Reviewed: December 1, 1999