Enhance the Sensibility of the Resonance Type Eddy Current Testing

Abstract

Eddy current testing (ECT) is one of the most representative nondestructive testing methods for metallic materials, parts, structures and so on. This paper proposes improvement of sensibility of the impedance sensing type ECT. Sensibility of the ECT is improved by means of three steps. One is an optimum exciting frequency selection. We employ the natural parallel resonant frequency of ECT coil. The second is to increase the sharpness of the resonance curve on impedance versus frequency characteristic by changing the coil connection. Finally, we attach externally capacitor to reduce the resonance frequency into low. This makes it possible to enhance the sensibility of the impedance sensing type ECT operating at the resonant frequency.