Dual Induction Eddy Current Probe for Vibration Noise Reduction

In eddy current testing, signals originating from product vibration and cracks are detected. Frequency filtering methods are widely used, such as vibration signal suppression. However, this method is not effective when the difference between the frequencies of the vibration and crack signals is small. We have proposed a dual induction method with passive vibration signal suppression that does not require active signal processing such as the frequency filtering method. This paper quantitatively describes the performance of a dual induction eddy current probe that selectively suppresses only the vibration signal from detection signals, comparing this with the frequency filtering method and the multi-frequency method. Simulation and measurement results show that the proposed probe suppresses vibration signals and does not suppress crack signals; however the current methods suppress both signals. The obtained results suggest that the proposed method provides a higher signal-to-noise ratio than the current method.