Abstract: To the study of resin in-plane flow in fabric preforms during the liquid composite molding (LCM) process, the influence of stitch mode and overlay placement styles and binder on the in-plane permeability of fabric performs were investigated by using of linear sensor device and 2D radial testing technique. The results indicate that the internal flow behavior and permeability in fabrics with different stitch and overlay placement styles and binder treatment are different significantly. If flow channels by stitch and overlay placement are along fiber direction, the permeability is higher along channel direction, which makes the principle permeabilities K₁ and K₂ different significantly and flow anisotropically. If there is an angle between flow channels and fiber direction, the principle permeabilities are small difference and flow close to isotropy. The thermoplastic binder in preforms are melted in LCM process which can change the distribution of binder powders and internal pore sizes. The thermoplastic binder after melted reaction in preforms will form more discrete adhesion film groups on fiber surface and bigger channels and pores, so resin flow faster and have higher permeability than before melt reaction.

Key words: permeability, liquid composite molding (LCM), overlay placement, stitch, binder, resin flow front