Conference Paper

Numerical 3D Permeability Prediction Using Computational Fluid Dynamics

To read the full-text of this research, you can request a copy directly from the authors.


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 %.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Microscopic simulations are object of research for many years in the field of fiber-reinforced polymers (FRP),. Next to microscopic simulations of FRPs and permeability prediction of yarns [1], some filament based simulation approaches for the deformation of carbon fiber yarns are described in literature [2,3,4]. Although, the friction mainly describes the interaction of the filaments, the authors used values that were derived at yarn level or estimated [2,3,4]. ...
Full-text available
The friction between carbon filaments has a big impact on the deformation of dry yarns. Therefore, to simulate the deformation of yarns on a microscopic level, it is very important to obtain the true friction coefficient at different boundary conditions. The stiffness properties of the yarns change when other parameters, such as the fiber volume content, the tension or the speed of the deformation, vary. Considering processes that combine the forming and the impregnation steps (e.g. wet molding), the resin additionally influences the friction. Presenting a newly developed experimental setup for the friction measurement between filaments is the focus of this paper. In particular, the influence of the normal force, the relative velocity, the angle between the filaments, the presence of unpolymerized matrix and its viscosity are investigated, using design of experiments..
... Discrete determined permeabilities are mapped on a two dimensional macroscopic finite element net and a liquid compression molding simulation is performed. This helps defining inlets, outlets and injection pressures in the real manufacturing process [3]. ...
... Somit soll einerseits eine optimale Fertigung, in der das spezifische Verhalten des verwendeten Materials berücksichtigt wird, gewährleistet und andererseits die Eigenschaften des finalen Bauteils detailliert vorhergesagt werden. [3]. ...
Full-text available
A unit cell based Computational Fluid Dynamics model is presented for predicting permeability of multilayer fabric structures. In Liquid Composites Moulding processes, fabric lay-ups undergo significant manufacture-induced deformation, combining compression, shear, and inter-layer nesting. Starting from the configuration of un-deformed fabric, the deformation is simulated geometrically by accounting for self-imposed kinematic constraints of interweaving yarns. The geometrical modelling approach is implemented in the open-source software TexGen. The permeability tensor is retrieved from flow analysis in ANSYS/CFX, based on TexGen voxel models. Using only measured geometrical data for un-deformed fabrics, deformed plain weave fabric and twill weave fabric lay-ups were modelled and their permeability tensors predicted. Comparison with experimental data demonstrates the generally good accuracy of predictions derived from the proposed numerical method.