A MODELING APPROACH TO THERMOPLASTIC PULTRUSION .1. FORMULATION OF MODELS

A fundamental understanding of the effects of processing parameters and die geometry in a pultrusion process requires a mathematical model in order to minimize the number of necessary experiments. Previous investigators have suggested a variety of models for thermoset pultrusion, while comparatively little effort has been spent modeling its less well understood thermoplastic counterpart. Herein, models to describe temperature and pressure distributions within a thermoplastic composite as it travels through the pultrusion line are presented. The temperature model considers heat transfer in an infinite slab with either prescribed boundary temperature, or prescribed heat flux from the surfaces. The pressure model is based upon matrix flow relative to the fibers and incorporates a non-Newtonian matrix viscosity and a temperature-dependent matrix density. A model to calculate the accumulated pulling resistance from a pultrusion die, arising from viscous, compaction, and friction resistance, is also presented. The models are evaluated studying an ideal pultrusion process for manufacturing of unidirectional carbon-fiber-reinforced polyether etherketone composites.