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.

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Resin transfer molding and vacuum-assisted resin transfer molding are two of the most commonly used liquid composite molding processes. For resin transfer molding, mold filling simulations can predict the resin flow patterns and location of voids and dry spots which has proven useful in designing the mold and injection locations for composite parts. To simulate vacuum-assisted resin transfer molding, even though coupled models are successful in predicting flow patterns and thickness distribution, the input requires fabric compaction characterization in addition to permeability characterization. Moreover, due to the coupled nature of flow and fabric compaction, the simulation is computationally expensive precluding the possibility to optimize the flow design for reliable production. In this work, we present an alternative approach to characterize and use an “effective” permeability in the resin transfer molding solver to simulate resin flow in vacuum-assisted resin transfer molding. This decoupled method is very efficient and provides reasonable results. The deviations in mold filling times between experiments and simulations for the resin transfer molding process with E-glass CSM and carbon 5HS were 4.7% and 1.0%, respectively, while for the vacuum-assisted resin transfer molding case using “effective permeability value” with E-glass CSM and carbon 5HS fabrics were 11.1% and 12.3%, respectively, which validates the approach presented.

The main hurdles in Vacuum Infusion (VI) are the difficulty in achieving complete mold filling and uniform part thickness. This study integrates process monitoring by full field thickness measurements and resin flow modeling that accounts for compaction and permeability characterizations of fabric reinforcements to assess the evolution of part thickness during filling and post-filling stages of VI process. A Structured Light Scanning system is used for full field thickness monitoring in experiments and a Control Volume Finite Element Method solver is implemented to couple resin flow with fabric’s compaction and permeability. Two cases are studied both experimentally and numerically. Evolutions of thickness and pressure validate the developed flow solver, its accuracy in terms of predicting fill times and fill patterns, suitability and limitations of the elastic compaction models for thickness modeling.