Multifunctional sensor yarns for real-time in situ detection of multiple damage mechanism for continuous structural integrity monitoring of components made of textile-reinforced composite materials

该研究项目致力于开发一种新型的同轴传感器纱线，该纱线只有三层功能层，具有可重现的质量和明确的均匀几何形状，设计为一种精确的、连续熔纺的芯/套双组分单丝结构。核心由热塑性聚合物PEEK组成，PEEK与导电粒子渗透混合，完全封闭在没有添加剂的裸露PEEK护套中。这种耐高温高性能聚合物适合直接集成到所有技术相关的热塑性塑料和热固性基质系统中。此外，这项研究的目的是开发工艺，以在湿化学沉积在芯鞘结构上并作为外部导体的镍层中，以周期性施加截面梯度的形式实现定义的可参数化电反射栅格。此外，还将首次研究基于电时域反射仪(E-TDR)的光纤测量方法的发展。因此，必须研究与之相关的高空间分辨率，以研究多种结构损伤机制发展和扩展的不同阶段或几何特征。这是其可靠的非破坏性测量的前提，也是对纤维增强塑料复合材料部件进行精确定位或全局可区分的原位检测的前提。这一创新的方法是基于通过进一步开发的熔融纺丝技术来整合生产具有严格均匀、可重复和无短路结构的双组分包芯/包层单丝等传感纱，以满足多种需求。两种基于电时域反射仪的新方法被用于生产多功能纱线和机器可处理的组合传感器，该传感器可用于各种测量。必须为这两种情况开发一种可靠的接触解决方案。它基于这样的工作假设，即由外部叠加载荷在FKV中引发的应力直接导致可检测的结构事件改变微观结构，并且根据其严重程度，仅导致在被监测部件的尺寸上整合的传感同轴导体结构的局部或全局几何变化。同轴传感器在几何反射点区域中的这种全局或局部几何变形允许测量波阻抗的局部变化，这允许与定制的评估策略相结合，对由结构退化引起的结构变化进行精确的空间分辨(重新)定位。

The research project focuses on the development of a novel coaxial sensor yarn with only three functional layers, equipped with reproducible quality and defined homogeneous geometry, which is designed as a precise and continuously melt-spun core/sheath bicomponent monofilament structure. The core consists of the thermoplastic polymer PEEK, which is percolatively mixed with electrically conductive particles and completely enclosed by a bare PEEK sheath without additives. This high-temperature resistant high-performance polymer is suitable for direct integration into all technically relevant thermoplastic and thermoset matrix systems. Furthermore, the research aims the process development for the realization of defined parameterizable electrical reflection gratings in the form of periodically impressed cross-sectional gradients in the nickel layer deposited wet-chemically on the core-sheath structure and acting as an outer conductor. Additionally, the development of a fiber-based measuring method based on electrical time-domain reflectometry (E-TDR) will be investigated for the first time. The hereby related high spatial resolution for the investigation of different stages or geometric characteristics of the development and propagation of multiple structural damage mechanisms has to be investigated. This is premise for their reliable non-destructiv-measurement as well as for the precisely localizable or globally differentiable in-situ detection in components made of fiber-reinforced plastic composites. The innovative approach is based on the integral production of such sensor yarns as bicomponent core/sheath monofilament yarns with strictly homogeneous, re-producible and short-circuit-free construction by means of melt-spinning technology further developed to meet manifold requirements. Two novel approaches based on electrical time-domain reflectometry are being pursued for the production of a versatile yarn-based and machine-processable combination sensor that can be used for a variety of measurements. A robust contacting solution must be developed for both.It is based on the working hypothesis that the stresses initiated in the FKV by external superimposed loads lead directly to detectable structural events that change the microstructure and, depending on their severity, cause only local or global geometric changes in the sensory coaxial conductor struc-ture integrated over the dimension of the component to be monitored. This global or local geometric deformation of the coaxial sensor in the area of the geometric reflection points allows the measurement of the local change of the wave impedance, which allows in combination with a tailored to be developed evaluation strategy a precise, spatially resolved (re)-localization of struc-ture changes caused by structural degradations.