Due to its great functionality, the fiber reinforced thermoplastics (FRP) has been applied in industrial as one of the lightweight technologies for many years. However, the non-uniform shrinkage and warpage due to the fiber microstructure becomes one of the big challenges. To overcome the shrinkage and warpage problems, the bubbles introduced by microcellular process can be one of the solutions in FRP system. To date, how is the bubble effect on the fiber orientation is still not fully understood yet. In this study, the influence of the bubble on the fiber orientation through microcellular and conventional injection molding processes is investigated. Specifically, the bubble effect on the fiber orientation distribution (FOD) in conventional and microcellular injection molding has been conducted through Moldex3D 2020 version. Results showed that when the lower gas content is introduced into molten plastics, the generation of bigger bubble with lower concentration will enhance the fiber orientation in flow direction. Moreover, when more gas amount is introduced, the appearance of those increasing numbers of the smaller bubbles will push fibers orientation turn into the cross-flow direction. This phenomenon can be validated via experimental study. However, the FOD variation due to the bubble growth is not significantly in the real injection system. The interaction between the bubbles and fibers needs to be further decoupled which is our future work.
