Model validation of polymer curing processes using thermography

Abstract

Abstract It would be advantageous to have a direct model validation of curing processes of epoxy resin systems. Since a direct measurement of the curing evolution and, thus, validation of curing processes is not yet possible, the temperature development based on the exothermic curing reaction is of particular interest. This aspect represents the main focus of this article, which is based on an experiment with a curing epoxy resin sample including suitable boundary conditions, which can be reproduced by numerical simulations. The heat transfer coefficient of natural convection is determined both by empirical formulations as well as by use of temperature measurements. Using a thermographic measuring system, the surface temperature of the sample is measured throughout the curing reaction while the properties of the sample surface constantly change. The thermographic measurements reveal initial fluid streams due to internal convection within the sample, which stop after short period of time. For validation purposes between the experiment and the simulation, we provide a method to map the recorded pixel temperatures to a geometric coordinate system located in the center of the sample surface. Further, the numerical treatment of curing processes is briefly summarized. Finally, the numerical results are compared to the experimental data analysis. Deviations are critically discussed regarding possible errors.