Werkstoffoptimierung für serienmäßige RTM-Strukturbauteile

The RTM process (Resin Transfer Molding), as an efficient manufacturing process in the industrial sector, is largely automated. However, concerning the used materials and the resulting processing times there is still a big potential for economic improvement. An optimization of materials composition and preform design must always be accompanied by ensuring the mechanical suitability of the resulting laminates. Objective of this master thesis was initially to show the current state of the art in preform design for the RTM process and the attainable mechanical properties of corresponding composite materials on the basis of a comprehensive literature review. Subsequently for two RTM-suitable polyurethane matrix resin systems, a basic material characterization at both resin level, as well as laminate level (with glass and carbon fiber reinforcement) was performed. The following test methods were used: •Dynamic Mechanical Analysis •Tensile and compression tests •Fracture mechanical analysis to determine the critical fracture toughness and the interlaminar energy release rate The literature search revealed that especially today's textile preform design using stitching, sewing or weaving in the field of 3D reinforcements has a great potential in terms of improved damage tolerance and structural stability. The experimental characterization of PUR laminates showed that the glass fiber reinforced materials have both tensile- and compression properties on a similar level with respect to literature data of comparable epoxy laminates. The carbon fiber reinforced laminates achieved higher tensile strengths than comparable epoxy laminates, but lower tensile moduli and compressive properties, presumably due to a low fiber-matrix adhesion between PUR and carbon fibers and possible uncertainties in the measurements. Both, the fracture toughness on resin level and the interlaminar fracture toughness on laminate level were shown to be higher for the investigated PUR-resins compared with literature data for corresponding standard epoxy resins and laminates. However, the presented comparison with literature data in general is restricted due to the differences in fiber arrangements.