Tailoring of Textile Preforms for Fibre-reinforced Polymer Composites

The manufacturing of textile preforms is a well-established process for developing three-dimensional (3D) composite structures. The process of liquid composite molding (LCM) is an efficient method for the production of fibrereinforced polymer composite (FRPC) products. For the production of highperformance FRPCs, the sewn, the net shape, and ready-to-impregnate preforms are economically well suited in the LCM process [Mitschang, P., Ogale, A., Schlimbach, J., Weyrauch, F. and Weimer, C. (2003). Preform Technology: A Necessary Requirement for Quality Controlled LCM-processes, Polymers & Polymer Composites, 11(8): S. 605–622.]. Though the process of sewing has a long history, its usefulness in the area of composite manufacturing has not yet been fully exploited. The sewing technology, its associated parameters, required thread construction, and finally the stitch geometry are required to be considered thoroughly. Understanding the process of stitch formation and analysis of the available stitch geometries for preform stitching are the aims of this study. Various kinds of seams can be used in the preform development and structural assembling. The micrographic observations at the stitched zones help us to know the actual stitch geometry inside the FRPC structure, the amount of threads involved in each stitch type, the fibre displacement, and the structural properties. Furthermore, in order to widen the preform and the composite manufacturing practices, new technologies like single-sided-stitch, blind stitch, chain stitch, etc. are compared with the modified lock stitch. For structural reinforcements, the process-compatible carbon fibre thread, developed at the Institut fur Verbundwerkstoffe GmbH (IVW) has been explained in detail. In this paper, the usefulness of tailored preforming technology and process optimisation steps are described briefly.