Modeling of fiber orientation during injection molding process of polymer composites
Jacek Nabiałek
Quarterly No. 4, 2011 pages 347-351
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abstract Polymer composites with fibers are widely used as construction materials. Different fibers are used (eg. fiberglass). One method of forming composite materials is injection molding. The paper presents chosen results of investigations on polymer flow during the mould cavity filling phase of the injection molding process. The process is characterized by high dynamics, which causes several technological difficulties, both during injection mould design and during product implementation to the production stage. Deep understanding of the phenomena which occur during filling an injection mould may lead to a more effective design of the processing tools and shortening of the time for the implementation and production time. In the paper the theoretical basis for modeling fiber orientation in an injected polymer composite is described. The orientation and distribution of fibers have a substantial influence on the mechanical properties of a molded part. A computer simulation of the injection molding of a polypropylene composite with glass fiber (PP + 20% glass fiber, Aqualoy 125B, A Schulman NA) is conducted. Special attention is given to the results concerning the orientation of the fiber during processing. Selected results of the computer simulation of the flow velocity distribution of the composite, Poisson's coefficient and fiber orientation tensor across the molded part and selected cross-sections are presented. Significant discrepancies in the orientation of the fibers, depending on the nature of the flow of the injected composite are affirmed. These disparities affect the lack of uniformity of the mechanical strength of the molded part. The author plans to extend the scope simulation research to determine the effect of processing conditions on fiber orientation.