Simulation of RIM-process for polyurethane foam expansion in fiber reinforced sandwich structures

Warp-knitted spacer fabrics filled by rigid polyurethane foam within a reaction injection molding process offers a high potential for application as lightweight sandwich construction. For prediction of foam microstructure and finding appropriate process parameters the simulation of the propagation characteristics of PUR is done by using a coupled system of partial differential equations consisting Navier-Stokes-Brinkman equation. Time, temperature and polymerization dependent viscosity as input parameter for the model is determined by rheological experiments, the permeability tensor is obtained by image processing of the textile microstructure. Mold filling experiments as well as combined foam expansion and rheometer experiments validate the developed models.