Saturated transverse permeability of unidirectional rovings for pultrusion

The effect of microstructural evolution through compaction

Journal Article (2024)
Author(s)

O. Yuksel (University of Twente, TU Delft - Group Çaglar)

B. Caglar (TU Delft - Aerospace Manufacturing Technologies)

Guillaume Broggi (TU Delft - Group Çaglar, EPFL Switzerland)

Véronique Michaud (EPFL Switzerland)

Remko Akkerman (University of Twente)

İsmet Baran (University of Twente)

Research Group
Group Çaglar
Copyright
© 2024 O. Yuksel, Baris Caglar, G.C. Broggi, Véronique Michaud, Remko Akkerman, Ismet Baran
DOI related publication
https://doi.org/10.1002/pc.28171
More Info
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Publication Year
2024
Language
English
Copyright
© 2024 O. Yuksel, Baris Caglar, G.C. Broggi, Véronique Michaud, Remko Akkerman, Ismet Baran
Research Group
Group Çaglar
Issue number
7
Volume number
45
Pages (from-to)
5935-5952
Reuse Rights

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Abstract

The transverse permeability of roving/tow-based fiber reinforcement is of great importance for accurate flow modeling in the pultrusion process. This study proposes an experimental approach to characterize the roving-based fiber beds' permeability under different compaction conditions. The experimental permeability results of thick roving-based preforms were reported and compared with the permeability values of roving-based preforms in the literature. A representative preform was infused under vacuum conditions. Its thickness was varied to replicate the different compaction values observed in permeability tests. Micrographs were then collected from it and analyzed to highlight the microscale transformations caused by processing/compaction on the fiber arrangement. The analysis revealed that compaction resulted in the reorganization of filaments along the direction of the applied compaction. Overall, the uniformity of the spatial filament distribution, i.e., the homogeneity within the fibrous domain, increased with increasing compaction. Furthermore, the microstructural analysis demonstrated transverse anisotropy within the tested domains, indicating that the obtained permeability results represented an upper boundary. In addition to the experimental analyses, various transverse permeability models, which were developed based on recently introduced statistical descriptors of fiber distribution, were evaluated by using the statistical descriptors extracted from the analyzed cross-sections. Among these models, the one correlating the second neighbor fiber distance with apparent permeability exhibited good agreement with the experimental results. Highlights: Transverse permeability measurement of a roving-based reinforcement was presented. The influence of compaction on the microstructure was investigated at the filament level. Filament distribution in a pultruded profile was analyzed by using statistical descriptors. The results of the experiments and the models in the literature were compared. The correlation between microstructural features and apparent permeability was discussed.