Macro and micro-scale modeling of polyurethane foaming processes

Abstract

Mold filling processes of refrigerators, car dashboards or steering wheels are some of the many application areas of polyurethane foams. The design of these processes still mainly relies on empirical approaches. Therefore, we first developed a modeling approach describing mold filling processes in complex geometries. Hence, it is possible to study macroscopic foam flow and to identify voids. The final properties of polyurethane foams may vary significantly depending on the location within a product. Additionally, the local foam structure influences foam properties like thermal conductivity or impact strength significantly. It is neither possible nor would it be efficient to model complex geometries completely on bubble scale. For this reason, we developed a modeling approach describing the bubble growth and the evolution of the foam structure for a limited number of bubbles in a representative volume. Finally, we coupled our two simulation approaches by introducing tracer particles into our mold filling simulations. Through this coupling, a basis for studying the evolution of the local foam structure in complex geometries is provided. © 2014 American Institute of Physics.