Permeability estimation algorithm to simultaneously characterize the distribution media and the fabric preform in vacuum assisted resin transfer molding process

In vacuum assisted resin transfer molding (VARTM), available pressure for resin injection is limited to 1 atm. Therefore, layers of high-permeability fabrics, called the distribution media (DM), are included in the lay-up to enhance the resin flow. During injection, resin flows initially in-plane saturating the DM, and subsequently through the thickness impregnating the bulk preform. Therefore, the DM permeability governs the planar resin flow pattern and lead length, which is defined as the difference between the flow position in the DM and in the bottom preform layer adjacent to the tool surface. In this study, the DM permeability was investigated as a function of the preform lay-up. A new permeability estimation method, called permeability estimation algorithm (PEA), that can estimate permeability values of the DM and the preform simultaneously from a single experiment, was developed and validated. Using PEA, it has been shown that the DM permeability does vary with the preform lay-up.