Numerical simulation of pressure variation and resin flow in injection pultrusion

Injection pultrusion is a continuous process for manufacturing composite materials. To produce good quality parts it is essential that complete wet out of the reinforcement fibers is achieved in the injection chamber. To achieve good wet out of the fibers, the magnitude of the resin injection pressure is extremely important. The present study is focused on the effects of pull speed, fiber volume fraction, resin viscosity and compression ratio (taper) of the injection chamber on resin fiber wet out within the injection chamber for polyester-glass roving composites. The recommended injection pressures for complete wet out are predicted for a wide and comprehensive variety of processing variables; this work is novel in that it has new and comprehensive results not available in the existing literature. Darcy's law is used to model the fiber/resin system of injection pultrusion. The Gutowski [Gutowski, T.G., Morigaki, T. and Cai, Z. (1987). The Consolidation of Laminate Composites, Journal of Composite Materials, 21(7): 172-187.] permeability model is used to determine the transverse permeability and the Kozeny-Carman [Carman, P.C. (1939). Flow Through Granular Beds, Trans. Int. Chem. Eng., 15: 150-166.] model is used to predict the longitudinal permeability. The finite volume method is used to predict the resin pressure field, resin velocity field, and resin moving flow front location.