The flow-fiber coupling behavior and its effect on the dimensional variation of fiber-reinforced plastics (FRP) injection parts

Due to fiber reinforced plastics (FRP) materials have become one of the main lightweight technologies. The reason why fibers can enhance plastic property is because of their microstructural properties. Among the microstructural properties, the fiber orientation is one of the most important factors to influence product quality. However, the fiber orientation is still not easy to be understood. In addition, during the injection molding process, some interactions exist between melt flow and fibers. How these interactions affect the process and products is not yet fully understood. Hence, in this study, the flow-fiber coupling effect on FRP injection parts has been investigated using a geometry system with three ASTM D638 specimens. The study methods include both numerical simulation and experimental observation. Results showed that through the fiber orientation distribution (FOD) study, the flow-fiber coupling effect is not significantly at the near gate region (NRG). It might result from too strong shear force to hold down the appearance of the flow-fiber interaction. However, at the end of filling region (EFR), the flow-fiber coupling effect tries to diminish the flow direction orientation tensor component A11 and enhance the cross-flow orientation tensor component A22 simultaneously. This orientation distribution behavior variation has been verified using micro-computerized tomography (-CT) scan and images analysis by AVIZO software. Finally, the flow-fiber coupling effect also verified based on the shrinkage of the injected parts through different flow domains.補正完