Monitoring of filler distribution in resin with an electromagnetic wave transmission line

The authors previously presented a new method for monitoring resin flow and curing with a high-frequency electromagnetic wave transmission line constructed inside a structure. This method can provide information on discontinuities or distributions by using frequency characteristics or the time-domain response. In this paper, we applied our method for monitoring the defects in resin, such as uneven distribution of reinforcement or filler, voids or contamination, in the manufacturing process. The experimental results demonstrated the possibility of a transmission line as a monitoring tool and showed that the area with defects can be characterized by comparing with results of theoretical calculations.