Vacuum assisted resin transfer molding (VARTM) is an infusion process where a vacuum draws a resin into a one-sided mold.  A cover, or bag, is placed over the top of the resin to form a vacuum-tight seal. Then the vacuum is applied, drawing the resin into the mold.  This method is also referred to as vacuum infusion process (VIP) molding.

Vacuum assisted resin transfer molding (VARTM) is ideal for the manufacture of large-scale composite structures. However, gravitational effects on flow behavior can be significant in increasingly tall structures. In this study, an analytical solution incorporating the gravitational effects is developed to predict the flow and pressure distributions of uniform thickness preforms under vacuum infusion conditions. Injection scenarios of preforms of various lengths and inclination angles ranging from horizontal to vertical are studied. Nondimensional process parameters in terms of the resin fill time, mold angle, permeability, radius and length of injection tubes, and preform cross-sectional area for horizontal, downward, and upward injection scenarios are considered. The analytical results show good agreement with the experimental data collected in horizontal and vertical infusions. The parametric study provides insight into the design and optimization of the VARTM process for infusion of tall composite structures.