Analysis of Continuous Fiber Reinforced 3D Sandwich Parts with Integrated Foaming of the Core
Polyurethane gains increasing relevance as matrix material in composite parts with high fiber volume contents due to its reactivity and adaptability. To improve lightweight potential, fiber reinforced polyurethanes are used in sandwich structures, which show excellent stiffness to weight ratios. For 3D sandwich parts with continuous fiber reinforced top layers cost intensive 3D cores are usually applied. In order to provide a more economic solution, a wet pressing process has been developed at the Institute of Plastics Processing (IKV) at RWTH Aachen University, which enables the process integrated forming of polyurethane rigid foam systems. Thereby, the foaming pressure created by the polyurethane foam provides pressure for impregnating and consolidating the top layers. A pre-impregnation of the top layers is realized by vacuum assisted polyurethane spraying outside the pressing mold. In this paper the results of a process and part analysis are presented for the manufacturing of 2D and 3D sandwich parts. The polyurethane spray impregnation shows significant influence on the resulting part quality regarding the penetration of the top layers by the foam system. Optimum properties of the polyurethane matrix system e.g. reactivity and viscosity are defined based on the results of the analysis.
Authors: Christian Hopmann, Regina Wagner, Andreas Uelpenich, Arne Böttcher, and Kai Fischer
Conference: SAMPE Seattle 2017