Flexible Array ECT Probe with Equilateral Triangle Arranged Coils and Differential Setting

Abstract It is still a problem to be studied to inspect defects on curved surfaces with small dimensions. This paper presents an array eddy current testing (ECT) probe with equilateral triangle arranged coils, where the coils operate in a differential model to null the background signal and reduce the noise resulting in a high sensitivity to small defects. Furthermore, as each two adjacent couple of differential coils are 120° apart in space, the probe is sensitive to defects with different orientations. The probe is flexible and can be bent according to the curved surface. The feasibility of the probe is validated experimentally. Images were generated by using the probe to scan samples with machined defects. It seems that the defects can be observed from the processed images. The experimental results reveal that the probe can detect small defects with dimensions 1 mm*0.1 mm*0.3 mm and oriented in different directions on a 304 stainless steel sample.