TY - JOUR
T1 - Accurate Thickness Measurement of Multiple Coating Layers on Carbon Fiber Composites Using Microwave Cavity Perturbation
AU - Li, Zhen
AU - Wu, Changcheng
AU - Meng, Zhaozong
AU - Soutis, Constantinos
AU - Chen, Zhijun
AU - Wang, Ping
AU - Gibson, Andrew
N1 - Funding Information:
This work was supported in part by the Natural Science Foundation of Jiangsu Province under Grant BK20200427, in part by the National Natural Science Foundation of China under Grant 52105552, and in part by the Shuangchuang Project of Jiangsu Province under Grant KFR20020.
Publisher Copyright:
© 1963-2012 IEEE.
PY - 2022/1/27
Y1 - 2022/1/27
N2 - Current techniques for evaluating the multilayered coating thickness on carbon fiber-reinforced polymer composites are suboptimal; here, we present a new nondestructive microwave method using an open cavity resonator sensor. When the open end of the cavity is positioned on a conductive polymer composite, a resonant cavity is formed. The coating perturbs the surface impedance, causing a resonance frequency shift. In the modeling, the original endplate perturbation theory for a closed resonant cavity is modified, incorporating the effect of the coating. One-, two- and multilayered coating cases are studied, and a linear relationship is revealed between the resonance frequency shift and the coating thickness change. The accuracy of the model is confirmed by electromagnetic simulation performed with CST software and actual measurements. It is shown that the proposed sensor is insensitive to the conductivity anisotropy of the composite examined, offering easy implementation. For the coating thickness estimation, errors within ±5% have been observed, where two reference cases are used as a simple form of calibration. The method presented here offers efficient on-site evaluation of coatings on composite structures of aircraft and other applications.
AB - Current techniques for evaluating the multilayered coating thickness on carbon fiber-reinforced polymer composites are suboptimal; here, we present a new nondestructive microwave method using an open cavity resonator sensor. When the open end of the cavity is positioned on a conductive polymer composite, a resonant cavity is formed. The coating perturbs the surface impedance, causing a resonance frequency shift. In the modeling, the original endplate perturbation theory for a closed resonant cavity is modified, incorporating the effect of the coating. One-, two- and multilayered coating cases are studied, and a linear relationship is revealed between the resonance frequency shift and the coating thickness change. The accuracy of the model is confirmed by electromagnetic simulation performed with CST software and actual measurements. It is shown that the proposed sensor is insensitive to the conductivity anisotropy of the composite examined, offering easy implementation. For the coating thickness estimation, errors within ±5% have been observed, where two reference cases are used as a simple form of calibration. The method presented here offers efficient on-site evaluation of coatings on composite structures of aircraft and other applications.
KW - Analytical model
KW - cavity perturbation
KW - composites
KW - multiple coatings
KW - thickness measurement
U2 - 10.1109/TIM.2022.3146907
DO - 10.1109/TIM.2022.3146907
M3 - Article
VL - 71
JO - IEEE Transactions on Instrumentation and Measurement
JF - IEEE Transactions on Instrumentation and Measurement
SN - 0018-9456
ER -