For the transmission of extreme mechanical loads in multi-layer fibre-reinforced plastic composites (FRP) structural components with high wall thicknesses are required. However, with increasing composite thickness, production-related imperfections such as fibre misalignment also occur more frequently. Their formation mechanisms and influence on the resulting material behaviour are being fundamentally analysed in the DFG research project PAK 988 "DIWA". For this purpose, glass fibre-reinforced polyurethane resins are produced using braiding technology and the high-pressure resin transfer moulding process (HP-RTM), characterised using non-destructive testing methods and subjected to thermo-mechanical load tests.

In this paper, the formation, expression and evolution of fibre misalignment in the sequential manufacturing steps are continuuous examined in more detail. For this purpose, a synergetic combination of in-situ process monitoring, structure elucidation and accompanying numerical simulation is carried out. By producing different laminate structures with different fibre orientation, thicknesses and process parameters, a thickness-dependent imperfection classification is possible, which can be evaluated in follow-up investigations at the project partners. The results of DIWA can be used to derive evaluation criteria and process control strategies that will make it possible to evaluate and minimise composite imperfections in thick-walled laminates in the future.