Methodology for a near net shape, wrinkle-free production of textile preforms by using a segment based die draping

• Applicant: Professor Dr.-Ing. Jürgen Fleischer
• Subject Area: Lightweight Construction, Textile Technology ; Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 377740863

The shortage of energy and resources has significantly increased the importance of lightweight construction in industrial applications in the past years. One possible way of reducing weight is the use of fibre-reinforced plastics because they show particularly prominent characteristics in terms of density such as specific stiffness and specific strength. In this context, the resin transfer moulding (RTM) constitutes a promising method considering that on the one hand it allows the production of continuous fibre-reinforced plastics - awarded the highest lightweight levels - and on the other hand shows the potential of industrialisation with high volume production at one-minute intervals. Preforming within the RTM process chain has to be considered a critical process step though, since the shaping and draping of the very flexible textile fibres significantly influences the mechanical properties of the component. To ensure efficiency and competitiveness of the preforming process, the automation of different preforming technologies was investigated in many projects.The binder-forming-technology shows a great potential to reach a large-scale production. An interesting approach for automated draping is the use of segmented stamping dies. Accordingly, the textile ply stacking sequence is shaped similar to a deep drawing process by means of matrices, punches and sliders. The fixation of the layers to one another as well as the shape retention of the preforms is achieved by using a binder.To exploit the maximum potential of the draping process with segmented punches for a large number of different geometries, a systematic method for the process design is necessary. Based on a geometric analysis and a finite element draping simulation, a segmentation of the die and the sequence of the punches have to be determined. Here, adequate case distinctions, threshold values or quantitative restrictions as well as recursion or iteration regulations must be formulated and integrated into a targeted methodical scheme.The planned investigatons shall contribute to understand the mechanism during the automated preforming process using segmented punches. By following this method, design engineers shall obtain a division of dies and a sequence of the punches for nearly any shell-shaped geometry.

• DFG Programme: Research Grants