Investigation of the Discrepancy Between Optically and Gravimetrically Calculated Fiber Volume Fraction in Flax-Fiber-Reinforced Polymer
Maier C, Beckmann A, Wittmann A, Koch KP, Fischer G (2025)
Publication Type: Journal article
Publication year: 2025
Journal
Book Volume: 9
Pages Range: 103
Issue: 3
DOI: 10.3390/jcs9030103
Abstract
The fiber volume fraction significantly influences the mechanical properties of fiber-reinforced composites. However, accurate measurements can be particularly challenging in natural-fiber-reinforced polymers. This study compared indirect methods using gravimetric and volumetric measurements with a U-Net-based direct method using micro-CT images for flax-fiber-reinforced polymers made via compression molding at 2.33–13.5 bar. A notable discrepancy was observed between the direct and indirect methods, with the latter yielding a fiber volume fraction approximately 25% lower than what could be determined optically. This difference arose from the matrix being absorbed by the fibers, resulting in a mixed region between dry fiber and pure matrix, further explained using a four-phase model. Our findings indicate that the volume fraction depended on the applied pressure. Specifically, we established a linear relationship between the fiber volume fraction and the pressure up to 9.4 bar, beyond which the fiber volume fraction plateaued. Furthermore, we examined the impact of void distribution in relation to pressure. At lower pressures, voids were distributed irregularly throughout the composite, whereas at higher pressures, the overall number of voids decreased, and they tended to concentrate primarily in the center.
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Germany (DE)How to cite
APA:
Maier, C., Beckmann, A., Wittmann, A., Koch, K.P., & Fischer, G. (2025). Investigation of the Discrepancy Between Optically and Gravimetrically Calculated Fiber Volume Fraction in Flax-Fiber-Reinforced Polymer. Journal of Composites Science, 9, 103. https://doi.org/10.3390/jcs9030103
MLA:
Maier, Christoph, et al. "Investigation of the Discrepancy Between Optically and Gravimetrically Calculated Fiber Volume Fraction in Flax-Fiber-Reinforced Polymer." Journal of Composites Science 9 (2025): 103.
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