Continuous analysis and evaluation of production-related fibre misalignments in thick-walled fibre-reinforced plastic composite structures

为了扩大纤维增强塑料复合材料（FRP）在高应力结构部件中的应用范围，需要制造厚壁多层层合板。对于厚壁FRP构件的高效生产，编织技术和高压树脂传递模塑工艺（HP-RTM）是合适的。大量织物增强层的堆叠、HP-RTM工艺的高渗透压力以及聚合物基质材料的固化效应通常会导致生产过程中的纤维错位。这些主要形成在层压板平面中，但是随着层压板厚度的增加，它们在层压板厚度方向上也变得更加明显。总之，纤维错位可能是负责记录的准静态面内压缩强度随层压thick.The现象，导致厚壁FRP结构中的纤维错位的发生不成比例的退化进行检测，分析和评估在本研究项目中使用的例子，一个通用的测试结构的玻璃纤维和聚氨酯树脂。借助计算机断层扫描和其他无损检测方法检查了从将干预成型件插入渗透工具到高压渗透和固化的连续制造步骤，并使用数字孪生模型进行建模。在厚壁复合材料结构中，浸渍行为是复合材料缺陷发展的关键因素。在计划的项目范围内，厚壁编织结构在厚度方向上的浸渍行为将采用新的测试方法进行表征。实验研究的结果作为进一步发展的建模方法的基础，该方法描述了方向依赖的浸渍行为与援助的代表性体积elements.The浸渍过程中的压力条件的分析提供了有关的纤维错位的发展的phenomenol-ogy的信息。所记录的现象的影响可以通过准静态和循环，以及单轴和多轴载荷下的综合热机械调查进行评估。通过在线工艺监测、结构解析以及材料和结构测试的协同组合，可以为后续的工艺模拟和工艺控制策略奠定基础，以降低复合材料缺陷。

In order to increase the range of applications for fibre-reinforced plastic composites (FRP) in highly stressed structural components, it is necessary to produce thick-walled multi-layer laminates. For the efficient production of thick-walled FRP components, the braiding technique and the high-pressure resin transfer moulding process (HP-RTM) are suitable. The stacking of a large number of textile reinforcement layers, the high infiltration pressures of the HP-RTM process and curing effects of the polymeric matrix material often lead to fibre misalignments due to production. These are mainly formed in the laminate plane, but with increasing laminate thickness, they also become more pronounced in the laminate thickness direction. Altogether, the fibre misalignments are probably responsible for the documented disproportionate degradations of the quasi-static in-plane compressive strength with increasing laminate thickness.The phenomena that lead to the occurrence of fibre misalignments in thick-walled FRP structures are to be detected, analysed and evaluated within this research project using the example of a generic test structure made of glass fibres and polyurethane resin. The sequential manufacturing steps from the insertion of the dry preform into the infiltration tool to the high-pressure infiltration and curing are examined with the aid of computer tomography and other NDT-methods and modelled using a digital twin. In thick-walled composite structures, the impregnation behaviour is a key factor in the development of composite imperfections. Within the scope of the planned project, the impregnation behaviour of thick-walled braided structures in the thickness direction will be characterized with a novel test method. The results of the experimental investigations serve as a basis for the further development of modelling approaches, which describe the direction-dependent impregnation behaviour with the aid of representative volume elements.The analysis of the pressure conditions during impregnation provides information on the phenomenol-ogy of the development of fibre misalignments. The effects of the recorded phenomena can be evaluated by comprehensive thermo-mechanical investigations under quasi-static and cyclic, as well as uni- and multiaxial loads. Through the synergetic combination of online process monitoring, structure elucidation together with material and structure tests, the foundations can be laid for subsequent work on process simulation and process control strategies with regard to lower composite imperfections.