A study of fiber orientation in short fiber-reinforced composites with simultaneous mold filling and phase change effects

Most of the properties of injection molded short fiber-reinforced composites are
highly dependent on the patterns of their fiber orientation, which are induced by the flow. On
the other hand, in most practical injection molding processes, both filling and solidification of
the molten suspension takes place simultaneously. This behavior indicates that both filling and
phase change for solidification can occur at the same time and therefore affect the flow behavior
of the suspension, hence the fiber orientation. The aim of the current work is to present a
numerical analysis of fiber orientation prediction in a three-dimensional rectangular cavity
considering simultaneous mold filling and phase change of the suspending polymer. To trace the
flow front during the filling process, the volume of fluid method (VOF) has been used, while an
enthalpy-based approach was used to model the solidification. The standard Hybrid closure
model of Advani and Tucker was applied to approximate the evolved fourth order orientation
tensor during the fiber orientation calculation. To validate the developed numerical model, the
results of the simulation model were compared with available experimental data for the
rectangular cavity. The simulation results showed that they are in good agreement with the
experimental data. Hence, the numerical model could assist in decisions regarding the design of
polymer composite products.