The Effect of Fabric Architecture on the Processing and Properties of Composites Made By Vacuum Assisted Resin Transfer Molding (VARTM)

Abstract

The goal of this research project was to evaluate and compare the effect of fabric architecture on the processing and properties of composites made by Vacuum Assisted Resin Transfer Molding (VARTM). The fabric architectures investigated included plain weave, satin weave, and warpknit unidirectional. The fiber types included E-glass and standard modulus carbon fiber. Flat panels were fabricated with a lab scale VARTM process using an epoxy resin system. Fabric plies were cut to 45 cm x 30 cm (18 in. x 12 in.), and the number of plies used depended on the fiber areal weight of each fabric to produce panels of similar final thickness. The speed of resin infusion was recorded by visually monitoring the flow front which was visible through the bag. Fiber volume fraction was evaluated using thickness measurements, and porosity was investigated via optical microscopy. Mechanical testing was performed via tensile and 3-point flexure. The results showed the fabric type had minimal effect on the infusion speed with the exception of the plain weave and satin weave fiberglass. From the mechanical testing results, there are many comparisons made of the modulus, strength, and strain-to-failure results, for example carbon vs. glass, unidirectional vs. woven, tensile vs. flexure. The rule of mixtures was able to predict some but not all of these properties. The results, which are discussed in detail herein, illustrate the main advantage of selecting carbon vs. glass in stiffness driven applications.