In-plane permeability characterization of engineering textiles based on radial flow experiments: A benchmark exercise

Abstract

Although good progress was made by two international benchmark exercises on in-plane permeability, existing methods have not yet been standardized. This paper presents the results of a third benchmark exercise using in-plane permeability measurement, based on systems applying the radial unsaturated injection method. 19 participants using 20 systems characterized a non-crimp and a woven fabric at three different fiber volume contents, using a commercially available silicone oil as impregnating fluid. They followed a detailed characterization procedure and also completed a questionnaire on their setup and analysis methods. Excluding outliers (2 of 20), the average coefficient of variation (c v) between the participant's results was 32% and 44% (non-crimp and woven fabric), while the average c v for individual participants was 8% and 12%, respectively. This indicates statistically significant variations between the measurement systems. Cavity deformation was identified as a major influence, besides fluid pressure/viscosity measurement, textile variations, and data analysis.

Permeability and compaction behaviour of air-texturised glass fibre rovings: A characterisation study

“…As layups of mats and fabrics resemble the ply configuration in most common LCM processes, several setups for this type of material characterisation can be found in the literature. For permeability characterisation, special moulds have been designed for controlled linear or radial impregnation experiments (see literature 25–27 ). Similarly, for compaction experiments, a conventional universal testing machine can be used to test the compaction behaviour of a layup of fabrics or mats.…”

Flow-speed-controlled quality optimisation for one-shot-hybrid RTM parts

“…Furthermore, the geometry of the roof bar itself as well as the injection strategy might influence the two permeability measurement strategies. Studies have shown that the measured permeability of the same material can change by more than one magnitude dependent on the measurement procedure [51]. Therefore, it can be inferred that, if possible, the permeability measurements used for FSC should be performed in a process near environment.…”

“…For this set-up, the permeability tensor can be reduced to a single value representing the permeability along the flow direction. The permeability of the preform was characterized by the use of 2 D in-plane permeability experiments following the radial flow principle [51][52][53]. The preform was built as described in the capillary rise experiments section excluding the automated cutting step.…”

Liquid composite molding reproducibility in real-world production of fiber reinforced polymeric composites: a review of challenges and solutions

“…In that context, the effect of different preform characteristics (layer orientation, thickness, fiber volume content, tow structure/ size, etc.) on permeability [25,70,71] as well as the effect of the permeant [72] have been studied while different inter-university benchmark comparisons of permeability results (round robin studies) have been conducted [73][74][75]. The equipment to determine permeability (permeameter) currently is not standardized and its commercial availability is limited.…”