An analysis of the three-dimensional resin-transfer mold filling process

Resin-transfer molding (RTM) is a process in which thermosetting resin is injected into a mold cavity pre-loaded with a porous fibrous preform. For parts with small thickness, the mold-filling process can be modeled as two-dimensional by neglecting the resin flow in the thickness direction. However thicker parts require extensive resin flow through the thickness and thus the three-dimensional effect in the resin flow must be considered. In this study, numerical simulations of three-dimensional mold filling during RTM were performed. The governing differential equations were discretized by using the control volume finite element method (CVFEM). The CVFEM technique was employed bacause of its simplicity in handling the moving boundary problems. The temperature and the degree of cure were also calculated. In order to evaluate the validity of the numerical results, they were compared with exact solutions for simple geometries, and close agreement was observed. Experiments were also performed. To check the three-dimensional resin front location as a function of time inside the preform, an optical fiber was used as a sensing element. The agreements between the experimental data and the numerical results were found to be satisfactory. Numerical calculations for complicated geometries were also performed to illustrate the effectiveness of the computer code developed in this study.