The effect of fiber content and aspect ratio on anisotropic flow front and fiber orientation for injection-molded fiber composites

Abstract In state-of-the-art predictive engineering software for injection molded fiber composites, it is challenging to discuss the effect of fiber properties, including fiber content and aspect ratio, on the shell-core fiber orientation and anisotropic flow front. Recently, the flow-fiber coupled model of informed isotropic (IISO) viscosity was proposed for simulating the realistic flow-induced fiber orientation. At present, one attempts to improve the IISO viscosity in relation to fiber content and aspect ratio. Therefore, injection molding simulations of 30 wt% and 50 wt% short glass fiber-reinforced Polyamide66 (30 wt% SGF/PA66 and 50 wt% SGF/PA66) are performed in the IISO flow-fiber couple 3D-FVM (three-dimensional finite volume method) computation under the fixed aspect ratio of a r = 20. As a result, the predicted fiber orientation distributions are in good agreement with related experimental data, while the core width is increased with fiber contents. In addition, the anisotropic ear flow occurs at the higher content. Based on shear viscosity of 30 wt% SGF/PA66, one can directly alter fiber content as 50 wt% SGF/PA66 in the IISO computation to anticipate the reliable trend of fiber orientation and flow behavior. When the a r = 20 short fiber is lengthened as the a r = 50 long fiber, the core obviously becomes the wider. It is significant to investigate the difference between the decoupled and coupled computation, as well as the influence of the flow-fiber coupled and fiber orientation model parameters.