Investigation of Dynamic Pressure Behavior in a Pultrusion Die

Abstract

The fluid resin pressure rise in a pultrusion die inlet can have a significant effect on the quality of the pultruded product. An appreciable pressure rise is required to suppress void formation and promote good fiber "wet out." Most of the pressure rise in the die occurs in the short, tapered die entrance region. In this study a finite element model is developed to predict this pressure rise as a function of various process parameters for a given die entrance geometry. The fiber resin system was modeled based on the assumptions of Darcy's law for flow in porous media. The momentum equations were combined with the continuity equation to save computational time and memory. The resulting equation was solved using a Galerkin weighted residual based finite element method. This model predicts the pressure rise in the tapered entrance region of the pultrusion die as well as along the straight portion of the die. Variations in pressure rise in the die inlet as a result of changes in the pull speed, resin viscosity, and percentage fiber volume are presented. These results are important because they can lead to more appropriate process variables for obtaining a suitable pressure rise in the die.

Keywords

pultrusion die pressure finite element pull speed fiber volume resin viscosity

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