Method and process development for the infiltration of truss structures made of fiber-reinforced plastics with multilayer variable-axial fiber architecture (MerVa-2)

MERVA-2研究项目通过实验和数值模拟相结合的方法，研究了采用TFP工艺生产的多层变轴向纤维结构的纤维增强塑料(FRP)结构的渗透行为。在MERVA-1项目的第一阶段，利用树脂传递模塑对单层TFP结构的渗透行为进行了实验和数值研究。全面了解了微观、细观和宏观尺度上的渗透行为，以及变轴向纤维结构对充型过程的影响。为了能够为TFP结构制定可靠的浇注策略，了解多层纤维结构的渗透行为是非常重要的。考虑多层TFP预制棒的挑战在于纺织品结构的复杂性增加。多层的缝合导致了不能用单层的简单叠加来表示的多维流动前沿。其原因是流道在所有层中的发展，以及粗纱的额外压缩，这导致了强烈的非均质填充行为。在第二个项目阶段，这些更复杂的多层TFP结构的渗透过程将被理解和数值模拟。为此，将通过实验研究不同缝合方式和铺层取向的多层变轴向TFP预制件的细观结构以及细观结构依赖于细观结构的渗透行为。基于实验结果和对渗透结构的测量，建立了典型的多层TFP预制棒的细观和宏观模型，并针对现有的渗透断层进行了评估。此外，还将分析发生效应的可扩展性，并将开发一种方法，在必要时将中观模式信息传递到均化渗透率张量之外的宏观模拟。该项目的总体目标是可靠地模拟复杂的多层变轴向TFP结构和可能的断层的渗透过程，以便能够安全地规划、执行和评估未来的渗透过程。

The MerVa-2 research project deals experimentally and numerically with the infiltration behavior of structural fiber-reinforced plastic (FRP) structures with multilayer variable-axial fiber architecture produced by the Tailored Fiber Placement (TFP) process. In the first project phase MerVa-1, the infiltration behavior of single-layer TFP structures was investigated experimentally and numerically using resin transfer molding. Comprehensive knowledge was gained about the infiltration behavior on micro, meso and macro scales as well as about the influence of the variable-axial fiber architecture on mold filling. In order to be able to develop reliable gating strategies for TFP structures, an understanding of the infiltration behavior of multilayer fiber architectures is furthermore of importance. The challenge in considering multilayer TFP preforms lies in the increased complexity of the textile structure. The stitching of multiple layers results in a multidimensional flow front that cannot be represented by a simple superposition of single layers. The reason for this is the development of flow channels through all layers as well as an additional compacting of the rovings, which results in a strongly heterogeneous filling behavior. In the second project phase, these more complex infiltration processes of multilayer TFP structures are to be understood and numerically modeled. For this purpose, the meso-structure as well as the meso-structure dependent infiltration behavior of multilayer variable-axial TFP preforms with different stitch patterns and ply orientations will be investigated experimentally. Based on the experimental results and measurements of the infiltrated structures, meso and macro models of typical multilayer TFP preforms are generated and evaluated with respect to existing infiltration faults. In addition, the scalability of the occurring effects will be analyzed and an approach will be developed to pass meso-model information beyond the homogenized permeability tensor to the macro-simulation where necessary. The overall objective of the project is to reliably model the infiltration of complex, multi-layer variable-axial TFP structures as well as possible faults in order to be able to safely plan, execute and evaluate infiltration processes virtually in the future.