Investigation of the role of transverse flow in co-injection resin transfer molding

A co-injection resin transfer molding (CIRTM) process has been developed at the University of Delaware's Center for Composite Materials in collaborati on with the U.S. Army Research Laboratory. It enables two or more resins to be simultaneously injected into a mold filled with a stationary fiber pref orm. This process allows for the manufacturing of co-cured multi-layer, mul ti-resin structures in a single processing step. A separation layer is used to provide resin compatibility during cure and to control resin mixing. Sc aling issues relating the role of transverse permeability in resin mixing a re investigated. This study presents two different approaches taken to unde rstand the causes of transverse flow and to quantify the amount of transver se now that occurs during processing. The first approach, a one-dimensional model, explains the important parameters that govern resin flow in CIRTM. The second approach is based on an existing finite element code that is mod ified to allow for the injection of multiple resins. The total amount of tr ansverse flow was quantified using the finite element code. This research s hows that the 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.