ABSTRACT

The fabric structure of a preform deforms when draped over a tool surface. The resulting shear angle and fiber volume fraction are calculated by using the code DRAPE. The code uses a kinematic model where the fabric is replaced with a yarn net. Yarns are assumed inextensible and pinned at their intersection points. As in manufacturing practice, the undeformed preform can either be a flat sheet, or, a braided tube. If one drapes long axisymmetric tool surfaces with a flat sheet of preform, it may result in wrinkles and/or extreme shear angles. A braided tube of preform will ease the draping for such cases. Several different tool geometry were studied using the code DRAPE. The accuracy in numerical simulations of mold filling in RTM process is strongly dependent on the accuracy of preform permeability. Using a table of shear angle versus permeability tensor predicted by code PERM, the preform permeability due to draping is modified. Then, LIMS (Liquid Injection Molding Simulation) code is used for the filling simulation of the mold. Numerical results (flow front location and pressure distribution) indicate that the deformation due to draping plays an important role in the RTM process, and it should be taken into account in mold filling simulation of the process.