This research presents a investigation of long fiber-reinforced thermoplastics (LFT) with mixed fiber types, combining experimental analysis with numerical modeling techniques. By accurately predicting the stiffness of mixed fiber composites, the design margin between mono fiber reinforced materials can be effectively exploited, facilitating the use of such materials. For this purpose in particular, a novel application of the Mori–Tanaka approach with two different inclusions guaranteeing symmetric stiffnesses is presented. This is a method that has never been used before in field studies. In addition, the study integrates fourth-order plate-averaged orientation tensors measured and subsequently interpolated to improve the accuracy of the modeling. Consistency with the established shear-lag modified Halpin–Tsai method is demonstrated, confirming the suitability of both approaches for predicting the tensile modulus of GF and CF+GF. However, discrepancies between predictions and experiments for CF are attributed to the complex microstructure of the material caused by bundling and poor dispersion of the CF. Furthermore, the study reveals remarkable hybridization effects within the mixed fiber LFT, particularly evident in the 22% increase in elongation at break observed in CF+GF compared to CF. Overall, this research significantly advances the understanding and predictive capabilities regarding mixed fiber LFTs, which opens up a new design space of specific properties. This provides valuable insight for future research and industrial applications.

中文翻译：

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混合长纤维增强热塑性塑料的实验和均质取向相关特性


本研究将实验分析与数值建模技术相结合，对混合纤维类型的长纤维增强热塑性塑料 (LFT) 进行了研究。通过准确预测混合纤维复合材料的刚度，可以有效地利用单纤维增强材料之间的设计裕度，从而促进此类材料的使用。特别是为此目的，提出了 Mori-Tanaka 方法的一种新颖应用，该方法具有两种不同的夹杂物，可保证对称刚度。这是以前在实地研究中从未使用过的方法。此外，该研究还集成了测量并随后插值的四阶板平均方向张量，以提高建模的准确性。证明了与已建立的剪切滞后改进 Halpin-Tsai 方法的一致性，证实了这两种方法对于预测 GF 和 CF+GF 拉伸模量的适用性。然而，CF 的预测与实验之间的差异归因于 CF 的成束和分散不良导致材料的复杂微观结构。此外，研究还揭示了混合纤维 LFT 中显着的杂化效应，尤其明显的是，与 CF 相比，CF+GF 的断裂伸长率增加了 22%。总体而言，这项研究显着提高了对混合纤维 LFT 的理解和预测能力，从而开辟了特定性能的新设计空间。这为未来的研究和工业应用提供了宝贵的见解。