Impact damage detection on carbon fiber reinforced polymer tube by a mutual differential Bobbin probe

Carbon fiber reinforced polymer (CFRP) tube is utilized in large aperture deployable space antennas for its superior material properties. Impact damages on CFRP tube can significantly impair the load-bearing capacity of the tubes. Efficient and convenient non-destructive evaluation method of impact damage in CFRP tubes is essential. This study develops a high-frequency eddy current testing (HF ECT) finite element analysis method that accounts for both the dielectric properties and anisotropic conductivity of CFRP, and establishes a fiber bundle model that explains the operating mechanism of displacement current and eddy currents in CFRP, offering guidance for predicting HF ECT signals in CFRP. A high signal-to-noise ratio mutual differential Bobbin probe is developed specifically for detecting impact damage in CFRP tubes. A HF ECT experiment system is constructed and validated using impact damages induced by a force hammer, demonstrating the effectiveness of method and probe, and the invisible impact defect is detected successfully.