Resin Impregnation During the Manufacture of Thermoplastic Matrix Composite Materials

Abstract

A numerical investigation was performed into the resin flow that occurs during the manufacture of thermoplastic matrix composite materials. Specific attention was directed towards modeling the fiber/matrix consolidation that occurs during resin film stacking/compression molding processes. The understanding of these processes is important to the field of composite materials because it is desirable to know the proper processing conditions to apply during manufacturing to obtain completely consolidated, void-free thermoplastic resin composite parts. The numerical study was based on the assumption of two-dimensional Darcy flow through stationary porous media. Fiber motion was neglected and quasi-steady state flow conditions were assumed. Inhomogeneity and anisotropy of fibrous preforms were allowed for. Due to the degree of geometrical complexity inherent to impregnation processes, the computational technique of boundary-fitted coordinate systems encompassing numerical grid generation was used and was found to be suitable for solving flow problems involving moving boundaries. The boundary conditions chosen for the investigation include constant applied pressure at the inlet, no-slip flow conditions along all walls, and vanishing shear stress along the impregnation front. Resin front/mold wall contact point movement was accomplished using either a no-slip based relocation algorithm or an imposed orthogonality method. Results are presented in the forms of temporal impregnation front positions and neat resin depth distributions for two sample process configurations. From the analysis of this information, processing parameters are suggested with which the successful manufacturing of thermoplastic composite materials can be accomplished. The need for further experimental and analytical work in this area is also discussed.