Abstract: To the study of resin flow and transverse permeability in thicker fabric preforms during the liquid composite molding (LCM) process, the experimental study of the internal flow behavior and permeability in thicker fabric structure reinforcement were investigated by using of ultrasound sensor monitor technique testing device. The results indicated that the internal flow behavior and permeability in different fabrics (twill, bi-axis warp knitting and unidirectional fabric) are different significantly. The transverse permeability is decrease in light area weight fabric with same structure for more layers and narrower flow channels in it. The transverse permeability in bi-axis warp knitting fabric is lower than twill fabric at low fiber volume fraction, while transverse permeability in bi-axis warp knitting fabric is higher than twill fabric at tight fiber stacks. The in-plane flow in unidirectional fabric is easier than twill and bi-axis warp knitting fabric, and transverse permeability is lower about one or two order of magnitude than the other fabrics.

Key words: permeability, liquid composite molding of composite, resin flow front, carbonfiber, ultrasonic sensor monitoring technique, fabric structure