Development and validation of a coupled meso-macro drape model for woven fabrics considering complex mechanisms at the roving level

• Applicant: Dr. Thomas Gereke
• Subject Area: Lightweight Construction, Textile Technology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 498784926

As the importance of lightweight construction continues to grow, fiber-reinforced polymers (FRP), especially with a textile reinforcement structure, are increasingly being used alongside classic construction materials such as aluminum or steel. In a typical manufacturing process for shell components made of FRP using the liquid impregnation process, dry textile structures are stacked, formed into the preform and impregnated with a thermoset resin system, e.g. using the resin transfer molding (RTM) process. Woven fabrics are more formable than unidirectional fabrics, which significantly facilitates the production of FRP components with double-curved, complex shapes. Defects created during preform fabrication, such as wrinkles, fiber waviness, gaps and fiber misorientations, reduce the mechanical performance of the composite part. FRP structures and preforms based on carbon fibers exhibit electrical conductivity that enables the use of high-resolution eddy current technology. The reconstruction of the complete yarn path using eddy current has so far only been performed for in-plane stretched textile configurations (e.g. non-crimp fabrics). For woven fabrics with their pronounced out-of-plane ondulation of the fibers, a fiber course reconstruction has not been possible so far. Numerical investigations are mainly performed with continuum mechanical macro-scale models. However, mesoscopic effects caused by friction, sliding, buckling or compression of rovings cannot be reproduced. On a smaller scale (unit cell), micro- and meso-scale models have also been developed, but their shortcomings are the high computational cost of drape simulations. The objective is to create an in-depth understanding of the impact of structural effects on the behavior of the textile structure during draping, and from this to determine a material routing and gradient textile structure adapted to the component shape and requirements. To this end, a coupled meso-macro model for 2D and 3D woven fabrics will be developed and validated to represent the meso- and macro-level effects (i.e., wrinkles, ondulations, gaps, etc.) that occur during draping, incorporating the complex mechanisms at the roving level. The macro-scale model is intended to represent the geometry globally, while the meso-scale model is applied locally in areas of special interest (region of interest, ROI). To this end, a precise validation technique that can be used for flexible configurations will also be developed using 100 % thread reconstruction based on eddy current testing technology that is suitable for woven fabrics.

• DFG Programme: Research Grants