Fabrication of high quality composite laminates by pressurized and heated-VARTM

Although vacuum-assisted transfer molding (VARTM) is preferred for manufacturing medium to large composite parts due to its simple tooling and low cost, part quality dictated by dimensional tolerances, void content and mechanical properties is usually low due to inherent limitations of the process. In this study, the conventional VARTM process was modified by external pressurization of a heated mold to increase fiber volume fraction and improve mechanical properties of laminates. During post-filling, various levels of external pressure were applied in a pressure chamber mounted on top of the mold. It was observed that pressurized VARTM led to laminates with less than 1% void content. In addition, fiber volume fraction and flexural strength were increased 25% and 13% with respect to non-pressurized VARTM, respectively which demonstrates the potential for manufacturing considerably higher quality composites by pressurized VARTM.