Evaluation of fiber orientation of SFRP during molding by numerical method of local area migration

Short fiber-reinforced plastic (SFRP), which involves compounding discontinuous fibers with resin, exhibits excellent specific strength, specific stiffness, and moldability, along with low cost, making it particularly active in the automotive sector for the conservation of the Earth's environment and the efficient use of energy resources. SFRP is mainly manufactured by injection molding, but defects such as resin filling deficiency, void formation, and fiber agglomeration or orientation bias are possible, highlighting the importance of setting appropriate molding conditions to achieve proper fiber dispersion and orientation. Considering the vast number of molding parameters, including resin flow rate, mold temperature, and pressure, numerical analysis prior to experimental validation is deemed effective. Therefore, this study focuses on resin flow within the mold and aims to evaluate the influence of molding parameters on the skin layer, the outermost layer formed by the flow front during injection molding, through MPS-based analysis of local area migration in the flow front. As a result, it was elucidated that the rate of resin solidification progress is the dominant parameter affecting fiber orientation in the skin layer.