Computer simulation is helpful for understanding the manufacturing of pultruded advanced composites. This research involves a three-dimensional examination of the temperature and thermochemical aspects for the manufacturing of cartesian fiberglass-epoxy composite materials. Comparison of the computer generated predictions were made with experimentally measured temperature profiles and the degree of cure obtained using a Differential Scanning Calorimeter (DSC). A numerical model employing Patankar's [1] control volume based finite difference technique was employed for solving the governing energy and species equations used to model the entire heating (moving and non-moving) sections of the pultruder. This computer model can be utilized to establish functional relationships between combinations of pull speed, fiber volume, and die temperature profiles and can be employed to refine the pultruder for manufacturing composites, indicating the importance of controlling the processing parameters in producing quality pultruded products. Since this computer simulation is independent of predetermined laboratory values in generating results, it can establish the guidelines in the design of an advanced pultrusion machine itself, and in orchestrating the future development of advanced composite materials.
Computer simulation of the manufacturing of pultruded composite materials has been limited strictly to one or two-dimensional modeling of simple flat or circular shaped composites. This research presents the modeling of unsteady-state temperature and degree of cure distributions for the manufacturing of fiberglass-epoxy composite materials with irregular cartesian geometries in three-dimensions. The model is capable of predicting temperature and degree of cure distributions for composites with cartesian shapes in three dimensions, and temperature profiles in pultrusion dies without the aid of predetermined temperature values used as die wall boundary conditions. One of the benefits of this model is in designing the heating section of pultruder machines. Using a differential scanning calorimeter (DSC) the chemical kinetic parameters for Shell EPON 9420 epoxy resin were obtained. A finite difference control volume technique was utilized in the development of the numerical model for solving the governing energy and species equation used in modeling the entire heating section of the pultruder. The combinations of pull speed, fiber volume, and die temperature profiles can be modeled very economically in manufacturing composites for very specific needs. Since this research is not limited in terms of predetermined temperature values, it can be easily tailored to predict a multitude of temperature profiles suited for a pultrusion process. This research is also important because it provides realistic modeling of irregular cross-sectional geometries.
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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