Fiber deformation as a result of fluid injection: modeling and validation in the case of saturated permeability measurements in through thickness direction

The knowledge of the through thickness permeability is important for the design of modern liquid composite molding processes. In through thickness permeability measurements, the textile undergoes flow-induced compaction, changing the distribution of fiber volume content. As a consequence, results of permeability measurements show a dependency on the applied injection pressure, further denoted as apparent permeability. In the study presented in this paper, saturated permeability measurements were conducted for different fiber volume contents, varying the injection pressure. At the lowest fiber volume content used, the apparent permeability strongly varied with pressure. With increasing fiber volume content the dependency on injection pressure decreased, but it was not negligible. We used a simulation model for coupling of flow and fiber deformation in liquid composite molding in order to predict the apparent permeability in saturated through thickness permeability measurements. The input data for the simulation model were determined by measurements of saturated permeability, using a very low injection pressure, and textile compaction properties. With the proposed methodology, a good agreement of simulation and experimental results was achieved.