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Abstract

Properties of pultruded composites depend strongly on processing variables such as pull speed. Die wall temperatures may change depending on the size of the composite and the pull speed due to heat absorption or heat generation by the composite. It is the objective of this study to emphasize the importance of predicting and understanding the impact of die wall temperatures on centerline temperatures and degree of cure for composites of various thicknesses pultruded at different pull speeds. In order to accomplish this goal, a transient, three-dimensional numerical thermochemical heat transfer model for the heating section of the pultruder was developed. The governing energy and species equations for the composite were solved using a finite difference control volume scheme. The kinetic parameters for Shell EPON 9420 epoxy resin, determined using a heat flux type differential scanning calorimeter (DSC), were employed in this study.

Previous researchers have tended to ignore the variations in die wall temperature distribution or have relied on experimentally obtained die wall temperature data to develop models and make predictions. This research overcomes those restrictions by completely predicting the temperature profiles in the entire die, thereby providing the pultrusion engineer with the tools to design a heating section of a pultrusion machine. An operational envelope has also been developed to establish guidelines for maximum pull speeds that can be used to obtain a specified degree of cure in the composite.

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References

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Effects of Pull Speed on Die Wall Temperatures for Flat Composites of Various Sizes

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