Examination of the arrangement and shape of coils for permittivity measurement of dielectric sandwiched between carbon fiber reinforced plastics using electromagnetic induction testing.

The arrangement and shape of coils for permittivity measurement of a dielectric sandwiched between carbon fiber reinforced plastics (CFRPs) using electromagnetic induction testing (EIT) is investigated here. First, the influence of the electromagnetic shielding effectiveness of the CFRPs on the permittivity measurement using EIT was examined by finite element analysis (FEA). The effectiveness was lower than that of general metals, indicating that EIT can be used for permittivity measurement. Next, the coil arrangement and shape suitable for permittivity measurement were investigated by FEA. The use of two rectangular spiral coils, one as a driver coil and the other as a pickup coil, was adopted. Finally, the permittivity was measured experimentally using the coil arrangement, geometry, and test conditions determined based on the FEA results. The experimental results showed that the output voltage increased as the permittivity increased, demonstrating the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]