Experimental investigation of heat dispersion due to impregnation of viscous fluids in heated fibrous porous curing composites processing

Resin Transfer Molding (RTM) is a composite manufacturing process in which a fibrous preform is placed in a closed mold and a viscous resin is injected into the mold to fill the empty spaces between the stationary network of fibers. The fiber preform and the mold are usually hot and transfer the heat to the moving resin. In this paper, we carried out and experimental investigation to validate the importance of heat dispersion in RTM and the local thermal equilibrium assumption during the non-isothermal mold filling process. In addition, we have developed and expression for the temperature boundary condition at the moving flow front for this moving boundary mold filling process based on volume averaging method and verified it with experiments. The heat dispersion was found to vary linearly with Peclet number and contributed significantly to the temperature distribution in RTM. Using order of magnitude analysis, it was clearly shown that the local thermal equilibrium is a reasonable assumption to model RTM processes and was verified with experimental results. finally, as many fiber preforms consist of two scales of pore sizes, it is pointed out that further research is necessary in characterization and prediction of heat dispersion in dual scale porous media.