Analysis and modeling of the damage behavior of long-fibre-reinforced semi-crystalline thermoplastics considering fibre length and fibre curvature

除了已确立的短纤维增强热塑性塑料外，具有较长不连续纤维的热塑性材料（LFT：长纤维增强热塑性塑料）的重要性不断增加。LFT的微观结构受到各自制造工艺的强烈影响，其特征在于局部变化的纤维方向、纤维长度和纤维曲率。如果LFT受到越来越大的载荷，则会出现不同的失效机制，其特征不仅取决于载荷，还取决于微观结构的特征。在文献中，确实有作品，描述这些复合材料的失效行为，通过模拟个人的损伤机制，然而，不同的并行或连续到期的机制之间的区别，特别是，在物理特性的基础上的描述是一个具有挑战性的，尚未解决的问题。特别是对于LFT，纤维曲率对强度的影响可以说是未被探索的，计划中的项目就是针对这一研究空白而进行的。在IKV的初步调查表明，LFT的材料行为可以表示在良好的精度使用材料模型的基础上平均场（MF）理论与实用的计算时间。的损害行为，这主要是在微观层面上发起的，不能使用MF模型进行调整。因此，该项目的目的是使用平均场理论，考虑不同的纤维长度和纤维曲率的LFT的损伤行为的示例性描述。

In addition to the established short-fibre reinforced thermoplastics, the importance of thermoplastic materials with longer discontinuous fibres (LFT: long fibre reinforced thermoplastics) is continuously increasing. The microstructure of LFT is strongly influenced by the respective manufacturing process and is characterised by locally varying fibre orientations, fibre lengths and fibre curvature.If an LFT is loaded increasingly, there are different failure mechanisms whose characteristics depend each on the load, but also on the characteristics of the microstructure. In the literature, there are indeed works that describe the failure behaviour of these composites by modelling individual damage mechanisms, however, the distinction between different parallel or successively expiring mechanisms and in particular, the description on the basis of physical characteristics is a challenging and yet unsolved problem. Especially for LFT, the influence of fibre curvature on the strength can be called unexplored.The planned project aims in this research gap. Preliminary investigations at IKV have shown that the material behaviour of LFT can be represented in good accuracy using material models based on the mean-field (MF) theory with practicable calculation times. The damage behaviour, which is mostly initiated at the micro level, cannot be adjusted using the MF models. The aim of the project is therefore the exemplary description of the damage behaviour of LFT considering different fibre lengths and fibre curvatures using the mean-field theory.