Bubble motion through non-crimp fabrics during composites manufacturing

Bubbles motion through interbundle channels in biaxial non-crimp fabrics is modelled. The scenario is that formed bubbles move with the resin through these channels and are trapped if the channels become too narrow. By usage of a permeability network model, existing criteria on bubble deformation and a variety of analytical and probabilistic methods it is found that the paths of the bubbles depend significantly on the position of the threads keeping the fabric together and the number of fibres crossing the interbundle channels. Another result is that the pressure difference over a trapped bubble increases with 50% in a 3D geometry possible helping the bubble to escape. A third result is that, on average, the bubbles move biased to the direction of the tows. Finally, it is found that the predicted void distribution of bubbles after a major part of bubbles have moved through the system are in qualitative agreement with experimental data. (c) 2007 Elsevier Ltd. All rights reserved.