On the statistics of transverse permeability of randomly distributed fibers

Correia, Nuno; Catalanotti, G.

doi:10.1016/j.compstruct.2016.09.045

Cited by 15 publications

(8 citation statements)

References 37 publications

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“…In numerical model analysis, the RVE size needs to be large enough to describe the inherent properties of the material, however, when considering the computational cost, the size of the RVE was expected to be relatively small. Bodaghi et al [ 43 ] found that the expected value and SD of the statistical analysis of the numerical results tend to converge when the delta is greater than or equal to 30. Trias [ 44 ] suggests that the minimum value of ζ is 50, and ζ = 50 was used in this paper.…”

Section: Statistical Analysis Of Spatial Point Patternsmentioning

confidence: 99%

“…Periodic boundary conditions was applied to the edge of the RVE region, as shown in Figure 9, while the fiber surface was defined as the wall boundary condition, Δ p is arbitrary nonzero pressure difference, and the permeability is independent of the applied pressure difference. [ 43 ] The following is Equation ):

({, \begin{array}{c} p_{in} - p_{out} = normalΔ p \\ p_{1} - p_{2} = 0 \end{array})

…”

Section: Numerical Modelmentioning

confidence: 99%

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Micro‐flow model with a new algorithm of random fiber distribution over the transverse cross‐section

et al. 2020

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A new algorithm to rapidly create representative volume elements (RVE) with random fibers distribution of high volume fractional was proposed. Derived from the classical hard core algorithm, and the "molecular force" effect was introduced to eliminate the irreversibility of the generation process. The new algorithm can create fiber microstructures with constant or random radius, and the volume fraction can reach 80% and 85% respectively. The stochastic statistical analysis of the generated fiber distribution shows that the generated microstructure is completely consistent with the spatial random distribution. Micro-flow analysis was performed using the generated RVE, predicting the transverse permeability of the fiber tow, and the predicted results were in good agreement with the experimental results. A simple method for creating RVE with random distribution of fibers was provided for the micro-mechanical analysis of composite materials.

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Section: Statistical Analysis Of Spatial Point Patternsmentioning

confidence: 99%

({, \begin{array}{c} p_{in} - p_{out} = normalΔ p \\ p_{1} - p_{2} = 0 \end{array})

…”

Section: Numerical Modelmentioning

confidence: 99%

Micro‐flow model with a new algorithm of random fiber distribution over the transverse cross‐section

et al. 2020

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“…In general, it is difficult to obtain uniform matrix distribution during fabricating UDL because of close-packing of fibers, which results in the existence of fiber-clusters and resin-rich zones. [20] With decrease of ply thickness, the close-packing layers of fibers decrease, which allows more penetration of matrix into gaps between fibers. This slightly increases the average spacing in fiber-cluster zone while decreases the thickness of resin-rich zones.…”

Section: Fiber Contact Ratio In the Fibercluster Zonementioning

confidence: 99%

“…where χ is a shape factor to describe the difference of the fiber distribution between the transverse and the thickness directions. [20] R r = R f s i ψW ð11Þ…”

Section: Resistivity In the Thickness Directionmentioning

confidence: 99%

“…The decrease of ply thickness will increase the strength of the laminate, and the delamination is suppressed while the fiber breakage is extended with the decrease of fiber areal weight. [15] Bodaghi [20] statistically calculated the permeability of randomly generated porous media at different fiber volume fractions for the transverse flow in a unidirectional ply based on representative volume element (RVE). Most of these studies suggest that thin-ply can inhibit delamination and improve the mechanical properties of UDLs.…”

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Prediction on electrical resistivity of thin‐ply unidirectional composites considering electric tunnel effect

et al. 2020

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This article presents a model for equivalent conductive paths to predict the resistivity of thin-ply carbon fiber reinforced unidirectional laminate (UDL), which incorporates electric tunnel effect. A statistical method was used to calculate the effective intra-laminar conductive contact ratio and the number of inter-laminar conductive pathways. Resistivities of four samples with ply thickness varying from 0.02 to 0.1 mm were calculated. A detailed comparison between the predicted and measured resistivities in the longitudinal, transverse and thickness directions validates the present model, which reveals the influence of ply thickness on the resistivity of the samples. Analysis of the model indicates that the resistivity of UDLs in the fiber direction is mainly dependent on the volume fraction, and the resistivities in their transverse and thickness directions are related to both the volume fraction of fibers and the microstructure of UDLs. K E Y W O R D S carbon fiber, electric tunnel effect, resistivity prediction, thin-ply composites 1 | INTRODUCTION Carbon fiber reinforced polymers (CFRPs) are widely used in aerospace, automobile, and energy industries because of their high specific strength and stiffness. However, CFRPs do not often meet the desired electrical conductivity due to the insulating nature of its matrix polymer. [1,2] Various attempts have been made to improve the electrical conductivity of CFRPs, such as, using carbon fibers (CFs) with highly enhanced electrical conductivity, introducing conductive layers to composite structure, modifying the binding agent to include conductive nanoparticles, spraying conductive particles onto a reinforced material, and so forth. [3-5] It is important for composites to possess the required combination of mechanical and electrical characteristics, for which we suggest using thin-ply, as done and discussed in a previous research study. [6] A thin-ply is most fabricated with the CF spreading technique, so that the resin-rich layers of the ply are less dominant Jin-Na Zhang and Chao-Yang Wang contributed equally to this study.

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Saturated transverse permeability of unidirectional rovings for pultrusion: The effect of microstructural evolution through compaction

Yuksel,

Caglar,

Broggi

et al. 2024

Polymer Composites

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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.

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On the statistics of transverse permeability of randomly distributed fibers

Cited by 15 publications

References 37 publications

Micro‐flow model with a new algorithm of random fiber distribution over the transverse cross‐section

Micro‐flow model with a new algorithm of random fiber distribution over the transverse cross‐section

Prediction on electrical resistivity of thin‐ply unidirectional composites considering electric tunnel effect

Saturated transverse permeability of unidirectional rovings for pultrusion: The effect of microstructural evolution through compaction

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