JEC COMPOSITES MAGAZINE - Issue #53 - November/December 2009 - 58

finished fibre-reinforced composites that reduce handling and further process steps. Hence, both the cycle time and production costs can be downsized while enhancing product quality. For this purpose, the research team is developing an integrated modular machine concept for the continuous production of semi-finished fabrics on the basis of multiaxial warp-knitted non-crimped fabric (NCF). These semi-finished fabrics are locally reinforced, with locally adjustable drapability, and consist of large numbers of layers. They are used in the second approach and in the production of components with the abovementioned characteristics. Local reinforcements are produced by feeding textile structures parallel and vertical to the process direction. When developing a feeding module for the warp knitting machine, the main focus was set on large-scale reinforcement structures because of their difficult handling behaviour. The following figure shows a 3D drawing of this module. The drapability of NCF in the process direction can be adjusted by changing the bond type of warp threads and the stitch length [1]. A pattern disc changes the vertical position of a guide bar and therefore the bond type of warp threads. The patterning possibilities of warp Fig. 2: Feeding module for the warp threads are limited knitting machine. through this mechanical activation of the guide bar. In order to adjust local drapability, an electro-mechanically activated guide bar will be integrated into a warp-knitting machine with multiaxial weft insertion systems. economically-viable, cost-effective preforming process chains. For this purpose, ITA has developed a software program called EcoPreform which can design and assess preforming process chains in terms of technical feasibility and cost-effectiveness. Two performance indicators are given key importance: cycle time and unit costs. A preforming process chain for a flat panel with local reinforcements was designed on the basis of the developed methodology and the provided database, which was generated by experimentally Fig. 3: Multi-step preforming technologies. evaluating various cutting, handling and joining technologies. This manufacturing sequence was compared with the existing manual manufacturing process. With the new automated process, the cycle time can be decreased from 37.8 to 3.7 minutes and the unit costs can be lowered from €30.86 to €8.26. The next step of the project will be to design and assess process chains for the more complex component shown in Figure 1, and to achieve the designed processes in order to assess preform quality and processability in the subsequent impregnation and consolidation processes. Conclusion The research team’s interdisciplinary cooperation will contribute to the advancement of preform handling, impregnation and forming, not to mention developments in single-step and multistep preforming. The approaches and developments in the FOR 860 group of researchers are paving the way for the mass production of fibre-reinforced plastic components for structural applications. Contacts: tim.grundmann@ita.rwth-aachen.de andreas.schnabel@ita.rwth-aachen.de felix.kruse@ita.rwth-aachen.de thomas.gries@ita.rwth-aachen.de More information: www.ita.rwth-aachen.de Acknowledgment We would like to thank the Deutsche Forschungsgemeinschaft (DFG) for supporting and funding the FOR860 working group of researchers. In brief The DFG research project focuses on developing new process chains for fibre-reinforced plastic components and on integrating preforming, forming and crosslinking processes. Multi-step preforming The second approach uses textiles such as multiaxial non-crimp fabrics or woven fabrics, but more specifically the semi-finished products from the first approach. It converts them into near-net shape preforms in a sequence of automated process steps. Technologies for cutting, handling and joining semi-finished fabrics are individually analyzed and further developed (Figure 3). Highly efficient planning tools are needed to develop Reference [1] Hufenbach, W. (Editor.), Textile Verbundbauweisen und Fertigungstechnologien für Leichtbaustrukturen des Maschinen- und Fahrzeugbaus, Textile Verstärkungen, Halbzeuge und deren textiltechnische Fertigung S. 25-56,60-72; Bauteilfertigung S. 338-345,352-364 Dresden: SDV - Die Medien AG, 2007. jec composites magazine / No53 November - December 2009

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JEC COMPOSITES MAGAZINE - Issue #53 - November/December 2009

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #53 - November/December 2009