Draping, resin transfer molding, permeability, compound curvature, fiber orientation Resin transfer molding involves injecting a polymer resin into a mold that is filled with a fiber preform. When designing the mold filling process, it is difficult to determine the correct locations for injection ports and the correct injection pressures necessary for complete filling of the mold. This difficulty is due to the varying permeability of the preform throughout the mold.
Permeability refers to the ease with which resin flows through a preform.
Factors that affect permeability include the preform construction and mold geometry. When discussing mold geometry, draping may become an issue. Draping involves bringing a fiber preform into contact with a tool surface, and allowing the preform to deform to the tool surface. This deformation of the preform causes shearing of the fiber tows, which changes the permeability throughout the mold.