On the numerical simulation of injection molding processes with integrated textile fiber reinforcements

In the present article, the polymer melt impregnation of textile fiber reinforcements in an injection molding process is explored theoretically and experimentally. Simplifying the numerical simulation of the thermoplastic melt flow behavior a specific mold with integrated single-glass fiber bundle was developed and used for experimental fill studies with thermoplastic melt. The polymer melt impregnation of the fiber bundle in the injection molding process is modeled and calculated with Complex Rheology Polymer Solver (CoRheoPol), a simulation tool developed at Fraunhofer Institut fAr Techno- und Wirtschaftsmathematik by the present authors. Navier-Stokes and Navier-Stokes-Brinkman equations are used to describe the melt flow in a pure fluid region and porous media, considering the non-Newtonian flow behavior of thermoplastic melts. Experimental and numerical results are compared determining the filling fronts and fiber impregnation of the injection molded test samples. A clear relationship between the degree of impregnation, verified by magnified photomicrograph, and the position of flow front can be detected. A good correlation of simulated and experimental flow fronts against the degree of filling of the mold is observed too. The differences in macroscopic flow behavior between the cavity with and without an integrated fiber bundle with respect to the impregnation process can be simulated with high accuracy.