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

随着轻量化结构的重要性不断提高，纤维增强聚合物（FRP），特别是具有纺织增强结构，越来越多地与经典建筑材料（如铝或钢）一起使用。在使用液体浸渍工艺的玻璃钢外壳部件的典型制造工艺中，干燥的纺织结构被堆叠，形成预成型，并用热固性树脂系统浸渍，例如使用树脂传递模塑（RTM）工艺。机织织物比单向织物具有更强的成型性，这大大方便了双曲线形状复杂的FRP构件的生产。预制体制造过程中产生的缺陷，如褶皱、纤维波纹、间隙和纤维定向错误，会降低复合材料部件的机械性能。基于碳纤维的FRP结构和预制体具有导电性，可以使用高分辨率涡流技术。到目前为止，使用涡流重建完整的纱线路径仅用于平面内拉伸纺织品配置（例如，无卷曲织物）。对于纤维有明显的面外起伏的机织织物，纤维过程的重建到目前为止还不可能。数值研究主要采用连续力学宏观模型。然而，由粗纱的摩擦、滑动、屈曲或压缩引起的细观效应不能再现。在更小的尺度（单元）上，微尺度和中尺度模型也得到了发展，但它们的缺点是悬垂模拟的计算成本高。目的是深入了解在悬垂过程中结构效应对纺织结构行为的影响，并由此确定适合组件形状和要求的材料路线和梯度纺织结构。为此，将开发并验证二维和三维机织物的耦合中宏模型，以代表悬垂过程中发生的中宏效应（即皱纹、起伏、间隙等），并结合粗纱层面的复杂机制。宏观尺度模型旨在全局表示几何形状，而中尺度模型则在局部应用于特殊兴趣区域（兴趣区域，ROI）。为此，一种可用于灵活配置的精确验证技术也将被开发出来，该技术使用基于涡流测试技术的100%螺纹重建，适用于机织织物。

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.