Effect of carbon fiber fabric structure on transverse permeability in LCM process

To study the transverse permeability of resin flow in heavy fabric preforms during the liquid composite molding(LCM) process,a 3-D permeability tester based on ultrasonic sensor monitoring technique was used to carry out an experimental study of the flow behavior and permeability of the resin inside the heavy fabric reinforcement.The results indicated that the internal flow behavior and permeability of the resin in different fabrics(twill,bi-axis and unidirectional carbon fiber fabric) varied significantly.When the fabric structure is identical,the increase of layers due to small area density leads to more impedance to the flow channels and thus decreases the transverse permeability;when the volume fraction of fiber is low,the transverse permeability in bi-axis fabric is lower than in twill,and vice versa in the case of dense texture fabric;and the in-plane flow in unidirectional fabric is easier than in twill and bi-axis fabric,but its transverse permeability is very low,about one or two orders of magnitude than the other two fabrics.