Particle simulation for predicting fiber motion in injection molding of short-fiber-reinforced composites

This study proposes a numerical analysis for predicting fiber motion during injection molding of short-fiber-reinforced composites using the moving particle semi-implicit (MPS) method. Its meshless and Lagrangian nature enables us to track individual fibers and to easily represent free surfaces. In this study, the mechanism of fiber orientation in a T-shaped bifurcation was investigated experimentally and numerically. The fiber orientation of injection-molded glass-fiber/polypropylene composite was observed by X-ray CT. Despite the symmetric mold shape, there was asymmetric fiber orientation due to the mold filling process. Fiber motion in the bifurcation was then analyzed by the proposed simulation, and the fiber orientation was quantitatively evaluated in each small region. The prediction agreed well with the experiment, and the associated mechanism of fiber orientation is discussed. Furthermore, this approach explicitly demonstrates the interaction between fibers, which is an advantage of the proposed approach.