Process and performance evaluation of the vacuum-assisted process

Vacuum-Assisted Resin Transfer Molding (VARTM) is widely used for large-scale composite manufacturing of civil and defense applications. Here, the infusion process reduces part costs due to a decrease in labor, material, and equipment expenses compared to other composite manufacturing techniques. However, in order to replace conventional manufacturing methods for aerospace-quality parts such as autoclave processing, the VARTM process repeatability and part quality must be improved. The Vacuum-Assisted Process (VAP) (Filsinger, J., Lorenz, T., Stadler, F. and Utecht, S. (2001). Method and Device for Producing Fiber-reinforced Components Using an Injection Method, German Patent WO 01/68353 A1.) developed and patented by EADS Deutschland uses a gas-permeable membrane to allow for uniform vacuum distribution and continuing degassing of the infused resin. W.L. Gore & Assoc. GmbH has developed a suitable membrane in co-operation with EADS. The membrane is placed over the fabric layers, sealed to the tool, and connected to the vent to allow uniform vacuum on the fabric surface. The VAP results in a more robust VARTM process that minimizes the potential for dry spot formation as well as lower void content and improved dimensional tolerances. This research quantifies the performance improvements and compares them to the Seemann Composite Resin Infusion Process (Seemann, William (1991). Plastic Transfer Molding Apparatus for the Production of Fiber Reinforced Plastic Structures, U.S. Patent, 5,052,906) (SCRIMP), the most common variation of the VARTM process.