INVESTIGATION OF DYNAMIC PRESSURE BEHAVIOR IN A PULTRUSION DIE

The fluid resin pressure rise in a pultrusion die inlet can have a sig nificant effect on the quality of the pultruded product. An appreciabl e pressure rise is required to suppress void formation and promote goo d fiber ''wet out.'' Most of the pressure rise in the die occurs in th e short, tapered die entrance region. In this study a finite element m odel is developed to predict this pressure rise as a function of vario us process parameters for a given die entrance geometry. The fiber res in system was modeled based on the assumptions of Darcy's law for flow in porous media. The momentum equations were combined with the contin uity equation to save computational time and memory. The resulting equ ation was solved using a Galerkin weighted residual based finite eleme nt method. This model predicts the pressure rise in the tapered entran ce 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 o f changes in the Full speed, resin viscosity, and percentage fiber vol ume are presented. These results are important because they can lead t o more appropriate process variables for obtaining a suitable pressure rise in the die.