| The Resin Transfer Molding (RTM) process has gained popularity amongst composite manufacturers due to the surface quality and dimensional tolerances that can be achieved from this process. In this process, fiber preforms are placed in a rigid mold and resin is injected through a gate to fill the empty spaces between the fibers. Being a closed mold process, one cannot view the progression of flow during the filling stage. It has been commonplace that parts would contain regions unsaturated by resin. Not only would these parts have to be discarded, there was no knowledge as to how these unsaturated regions formed, and what to do to prevent repeat occurrence. Typically, a trial and error process is employed to attempt to correct for the problem.; By modeling the RTM process as flow through anisotropic porous media, one can simulate and predict the flow in the mold if the permeability of the fiber is known. However, during the preform preparation or handling the permeability along mold edges varies from one point to the next. It was discovered that disturbances inside the mold led to alterations in the flow progression. The approach taken in this dissertation will be to manipulate the flow progression by selectively opening and closing gates during the filling process. The goal of the manipulation is to direct the flow in such a manner that despite the disturbances, one will be able to completely saturate the fibers with resin.; The variation in flow progression is investigated and characterized using simulations. The fundamentals of flow manipulation are described with an introductory example. The true approach. A study quantifies the disturbance range and frequency in common manufacturing practice. With the nature of the disturbances better understood, several flow manipulation approaches were developed and compared. These approaches proved to be successful in the virtual manufacturing domain, but required experimental validation. Therefore, an experimental workstation was designed and built to accommodate the needs of the approaches. The workstation was used, and demonstrated the strengths and weaknesses of the various approaches. |
