In Vacuum Assisted Resin Transfer Molding (VARTM), fiber preform is placed on a rigid tool and sealed with a flexible plastic bag. Vacuum is drawn at the vent to compact the preform under atmospheric pressure with the injection line closed. When the injection line is opened the resin flows into the preform. The pressure of the incoming resin relieves some of the pressure being borne by the preform which increases the thickness of the preform during the infusion process. As the resin pressure varies from the injection location to the vent, the thickness of the part will not be uniform due to this resin pressure variation and its coupling with the compression characteristics of the preform. Compaction studies of the preform have identified elastic, plastic, and even viscoelastic behavior and a change in behavior as one goes from a dry preform to a wet preform (lubricated). This paper will describe results from a model that couples the fiber compaction behavior with the resin infusion process. Experiments will be conducted to measure the thickness of the preform during and after the infusion process is complete. The results will be compared with the model to identify the importance of the preform deformation in manufacturing of composites parts with the VARTM process.

Modern composite materials are becoming more and more advanced as engineers are better able to take advantage of their properties. In addition to their lighter weight and net-shape manufacturing, current interest is to make these materials multifunctional. This may require one to insert various objects into the composite to achieve a variety of different goals. It is important to understand how these embedded objects will affect both the manufacturing and the structural integrity of the component. In this work, the effects of impermeable embedded inserts on the infusion stage of vacuum-assisted resin transfer molding (VARTM) will be explored. In VARTM, one places a distribution media on top of the preform to aid the filling as the resin will first fill the face of the preform in contact with the distribution media and will then infuse the preform in the thickness direction. However, if one has an embedded impermeable insert in the thickness direction, it will obstruct the flow in the region below the embedded object. Several case studies are conducted to understand the effect of the geometry and placement of the embedded insert and the distribution media lay out and properties on the impregnation of the resin into the fiber preform. Finally, an approach is outlined to modify the layout of the distribution media in order to ensure a complete saturation of the preform under all but the most extreme conditions. The approach is validated with experiments. POLYM. COMPOS., 28: 442-450, 2007.