Influence of temperature on the behaviour at fibre misalignment in thick-walled Fibre Reinforced Composites

纤维增强聚合物（FRP）被确立为各种应用中的结构部件的设计材料。然而，制造引起的复合材料的缺陷，在平面内以及平面外，是至关重要的，因为纤维不再定向在加载方向由于错位，这大大降低了层压板的强度和刚度。本研究项目的目的是调查局部纤维错位（面内）和层压板水平层波纹度（面外）形状的结构不连续性对FRP力学性能的影响。一个特别的重点是设置在所谓的厚层压板单轴压缩和多轴加载条件下的行为的环境温度的影响。当调查FRP的力学性能的尺寸效应，它往往是不清楚是否是一个实际的材料尺寸效应或是否其他影响因素，如制造质量随厚度的增加而降低，发挥作用。在这种情况下，人为引入的缺陷可以进一步了解FRP层压板缩放中生产偏差的影响，同时确保一致的生产质量。FRP的压缩行为受基体性能的显著影响，而基体性能与温度有关。因此，调查的基础是关于热性能和机械性能以及温度-粘度行为的基质的表征。温度-粘度特性对HD-RTM工艺的发展具有决定性作用。在薄壁试样试验中确定的力学参数和材料性能对厚壁结构的适用性尚未明确，将在项目框架内进行研究。最后，研究结果将用于测试结构的多轴测试。因此，在不同的温度下的纤维错位和位移的影响组件样的结构，可以调查和相关的关键缺陷可以得出。

Fibre reinforced polymers (FRP) are established as a design material for structural parts in various applications. However, manufacturing induced composite imperfections, in-plane as well as out-of-plane, is critical, because the fibres are no longer orientated in loading direction due to the misalignment, which reduces strength and stiffness of the laminate significantly. The aim of this research project is the investigation of the influence of structural discontinuities in the shape of local fibre misalignment (in-plane) and on laminate level layer waviness (out-of-plane) on the mechanical properties of FRP. A special focus is set on the influence of the ambient temperature on the behaviour of so called thick laminates under uniaxial compression and multiaxial loading conditions.When investigating a size effect of the mechanical properties of FRP, it is often not clear whether it is an actual size effect of the material or whether other influencing factors, such as a reduction in manufacturing quality with increasing thickness, play a role. In this case, defects that have been artificially introduced can provide further insights into the influence of production deviations in the scaling of FRP laminates, while ensuring a consistent production quality.The compressive behaviour of FRP is significantly influenced by the matrix properties, which are temperature-dependent. The basis of the investigations is therefore the characterization of the matrix with regard to the thermal and mechanical properties as well as the temperature-viscosity behaviour. The temperature-viscosity behaviour is decisive for the development of the HD-RTM process.The applicability of mechanical parameters and material properties determined in experiments with thin specimens to thick-walled structures has not been clarified and will be investigated within the framework of the project.Finally, the findings will be used for the multiaxial testing of test structures. Thus, the influence of fibre misalignments and displacements at different temperatures on component-like structures can be investigated and correlations for critical defects can be derived.