Permeability measurements and prediction are one of the most critical parameters for LCM simulation and have been focused in research for many years. Experimental permeability measurements are time and material consuming, but necessary for today’s FEM simulation. Virtual permeability prediction is usually based on small mesoscopic RVE models or analytical approaches. Using these state of the art methods the transfer to large near-net-shape textiles is not applicable.
In this study, based on a plain mesoscopic triaxial 12K braid model created with WiseTex, TexGen and PAM-Crash, a method for numerical permeability prediction using an open source CFD code is introduced. The dimensions of the plate are 15 x 15 x 1 mm containing one layer and a fibre volume content (FVC) of 33 %. Furthermore a second compacted mesoscopic model is introduced to show the differences in permeability results. The dimensions of the compacted plate are 15 x 15 x 2 mm containing three layers and a FVC of 50 %.
A full-field fluid flow is simulated with a steady state semi implicit pressure induced solver (SIMPLE) of the software tool OpenFOAM. In a following step the 3D permeability tensor field is determined using Darcy’s equation and the calculated flow conditions. Challenges in meshing and permeability calculation are identified and possible solutions for near net shape structures are shown.
The results are compared between the two mesoscopic models, to different approaches of permeability tensor field calculation and to real experiments. The latter are executed with a radial test bench, a constant infiltration pressure of 2 bars and a 12K triaxial carbon braid with a FVC of 32.7 and 49.1 %.