Enhanced ability of defect detection using high voltage time-domain resonance analysis and impedance spectrum

Impedance spectroscopy is a well-established method for detecting mechanical defects in materials and structures activated by piezoelectric resonance. However, the detection sensitivity is not always satisfactory for very small defects, such as those that are of great importance for high-field insulation. In this study, an enhanced defect detection method is developed to solve this problem. A high-voltage (1 kV) time-domain resonance analysis is used in combination with conventional impedance spectrum analysis. The resonant frequencies and damping factors of the characteristic high-voltage piezoelectric resonances are extracted from time-domain data, and the damping factors are found to be more sensitive to the defect geometry. The results suggest that the time-domain method used here may have potential for applications where a high sensitivity of defect detection is required.