Untersuchung des Kompaktierungs- und Relaxierungsverhalten von trockenen, bebinderten Kohlenstofffaserpreforms

Abstract

The Center for Lightweight Production Technology (ZLP) of the German Aerospace Center (DLR) in Stade research on an automated RTM-process for an econonmic and large scale production of complex CFRP components. One of the major goals in automated production of composite parts is to guarantee process stability and, at the same time, high part quality. The quality of the finale composite part is highly influenced by the precise manufacturing of the net-shaped preform. The spring-back-effect of the fibre material, influenced by a great number of process parameters, leads to unacceptable preform deformations. As a result, structural defects occur within the final composite part. This master thesis addresses the compaction and relaxation behavior of even, dry and bindered fiber textiles (woven and non-crimb fabrics) during the consolidation process. Therefore, four process parameters (temperature, pressure, ply number and temperature dwell time) will be variied and combined with each other to analyse the impact of the mentioned parameters on the material's behavior. The consolidation experiments will be conducted with a test unit that was constructed as part of a former bachelor thesis. Furthermore, a long term relaxation of preforms will be investigated until 24 hours after the consoldation process by using a second test unit. After describing the validation procedure of the test equipment, the results of the investigation will be presented. The evaluation of the material's sensitivity regarding the four parameters will be carried out by bulk-factor-diagrams and first order sobol indices. Furthermore, response surface models (kriging) representing the material's relaxation behavior will be created for both materials. Finally, potential fields of work for future research will be presented.