Capillary phenomena in liquid composite moulding

In liquid composite moulding, capillary phenomena take place as the fibre/air interface is progressively replaced by the fibre/resin interface. These effects are often neglected when computing the flow front progression into the fibre preform, because the surface tension of the resins is low. However, these are recognized to exert an influence on the final void content of the part. In this article, we present experimental results from unidirectional infiltration of an epoxy resin under constant flow rate into non-crimp fabrics. The inlet pressure rise is shown to deviate from linearity, indicating a progressive saturation. A multiphase flow approach is proposed to model infiltration, assuming saturation curves and relative permeability dependence on saturation based on soil science literature. Numerical results using a FEM code show trends that are in good qualitative agreement with experimental results. The interest and validity of this approach is then discussed.