Nondestructive detection for carbon fiber-reinforced polymer pipes based on capacitive coupling principle and auto-balancing impedance measurement

This work presents a novel nondestructive electrical characteristic detection method for carbon fiber-reinforced polymer (CFRP). Unlike conventional electrical characteristic detection methods, the proposed method establishes a capacitively coupled electrical measurement model for CFRP, enabling measurements without the need for destructive preprocessing of the CFRP surface. To achieve small resistance measurements of CFRP at megahertz frequency, an auto-balancing impedance measurement strategy is implemented. This strategy incorporates an improved impedance measurement circuit and employs a pattern search method to optimize the excitation signal. Based on this method, a nondestructive detection system was developed for the electrical characteristic detection of CFRP. To estimate the reliability and accuracy of the method, a linearity validation experiment and damage detection experiment were conducted on CFRP pipe samples. The results confirm the effectiveness of the proposed method, demonstrating high measurement accuracy and indicating the system’s capability for reliable nondestructive electrical characteristic detection of CFRP.