Effect of the packing stage on fiber orientation for injection molding simulation of fiber-reinforced composites

Abstract

During the packing or post-filling stage, a significant flow of polymer inside the cavity may result due to the compressibility of the polymer melt under the higher packing pressure of the injection molding process. In the meantime, the effect of the packing stage on the shell–core structure of the fiber orientation for the fiber-reinforced composites has always been a concern. Even though certain commercial packages have undergone unified simulations of the filling and packing stages, fiber orientation has usually been determined at the end of the filling stage. A recently proposed mathematic model, Improved Anisotropic Rotary Diffusion and Retarding Principal Rate, having incorporated the state-of-the-art technology of 3D injection molding simulation, has demonstrated its ability to provide reliable predictions of fiber orientation. The present numerical results concentrate on comparing and analyzing the difference in fiber orientation between the filling and packing stages, while the important effects of packing time and packing pressure are further revealed. A qualitative comparison of core thickness widths in related experimental investigations is discussed herein.