Experimental investigation and flow visualization of the resin-transfer mold-filling process in a non-planar geometry

Abstract

Resin-transfer molding (RTM) is a manufacturing process for composite materials in which resin is injected into a mold cavity filled with a fibrous preform. Complete saturation of the preform during RTM is necessary for successful manufacturing and performance of the composite part. Unsuccessful filling of the mold may lead to the formation of macroscopic and microscopic voids, both defects significantly affecting the quality of the finished product. Recently much effort has been directed towards modeling and simulation of the RTM process. Such simulations usually model the filling of RTM molds as flow through porous media employing Darcy's law. An experimental study has been completed, the goal of which was to develop a library of experimental flow visualization and pressure measurement data. A mold was constructed, providing a moderately complex three-dimensional mold cavity. The cavity shape is a thin-shelled, five-sided box, having a base and four sides. The mold was built to provide flexibility, including multiple injection, pressure measurement, and venting sites. A wide variety of experiments were completed, varying a number of important processing parameters. All experiments were isothermal, both mold and fluid being held at room temperature. Several examples of the experiments completed are described, and organized into two case studies. The first case study demonstrates how three experiments were used in an initial investigation into the ‘racetracking’ phenomenon. The second study investigates the effect of preform fiber volume fraction on fluid injection pressure. Numerical simulations of the experiments have been completed which demonstrate how existing numerical simulation codes can be validated against the experimental data.