Thermal characterization for three-dimensional irregular shaped graphite and fiberglass epoxy based pultruded composites.

摘要

Fiber reinforced composite materials are becoming an increasingly dominant class of engineering materials. One of the most cost-effective and fastest techniques of producing composite materials is by pultrusion. Detailed computer modeling is required for the understanding, manufacturing and advancement of pultruded composites. This research involves a comprehensive three-dimensional examination of the heat transfer/thermochemical aspects of the design and manufacture of pultruded composite materials by investigating the transient temperature profiles and curing characteristics for graphite-epoxy and fiberglass-epoxy composites. Also simulated is the pultrusion of composite materials of various cartesian geometries in three-dimensions. Comparisons of the computer generated predictions were made with experimentally determined temperature profiles and degree of cure obtained using a Thermal Analyst model 2910 heat flux type differential scanning calorimeter (DSC). Die wall temperatures can change depending on the size of the composite and the pull speed due to heat absorption or heat generation by the composite. This study also emphasizes 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.; A numerical model based on Patankar's (1) control volume based finite difference technique was formulated for solving the governing energy and species equations used to model the entire heating section (moving and non-moving) of the PTI Pulstar 804 pultruder. An operational envelope is presented for optimizing the productivity of the pultrusion process.; This computer model can be utilized to establish functional relationships between the coupling effects of pull speed, fiber volume and heater platen temperatures. Computer modeling has the extraordinary ability of accurately predicting thermal and curing behavior without physically manipulating mechanical performance. The cost effective nature of modeling allows engineers to be more globally competitive. Since this computer simulation is independent of pre-determined laboratory values in generating results, it can establish the guidelines in the design of a sophisticated pultrusion machine and in orchestrating the future development of advanced composite materials.