Session: 07-01: NDE for Additive Manufacturing / 03-01: Electromagnetic NDE Techniques

Paper Number: 137844

137844 - Flexible Array ECT Probe With Equilateral Triangle Arranged Coils and Differential Setting 

Abstract: 

It is crucial to inspect defects with small dimensions and arbitrary orientations in a metallic structure to maintain its reliability and safety. In addition, since many structures, such as engine blades and crankshafts, have curved surfaces, the probe should be flexible to fit the irregular structure shape. An array eddy current testing (ECT) probe generates an image in a single probe pass, which effectively eliminates the raster scanning necessary when using ECT pencil probes. However, it is still a problem to be studied for an array ECT probe to detect small defects that are oriented in unknown directions. A conventional array ECT probe typically employs multiple channels to identify defects with different orientations, resulting in complex multiplexer circuits and complex signal processing algorithms. This paper presents a new array ECT probe with equilateral triangle-arranged coils. The coils operate in differential model to null the background signal and reduce the noise. Therefore, the probe has high sensitivity to small defects. Furthermore, as each two adjacent couples of differential coils are 120° apart in space, the probe is sensitive to defects in different directions. The probe is flexible, which can be bent according to the curved surface. The operation principle of the probe is studied based on a finite element method (FEM) model. Then the feasibility of the probe design is validated experimentally. Experimental results reveal that the probe can detect a defect with dimensions 2.5mm*0.1mm*0.1mm oriented in different orientations on a 304 stainless steel sample. The experimental image shows that the features of the defects can be clearly observed after the imaging process. As proved by the experiment, the probe can also identify defects under a thin non-metallic layer.

Presenting Author: Chenzhi Zhang ShanghaiTech University

Presenting Author Biography: Chenzhi Zhang is currently working toward a bachelor's degree in electrical engineering at ShanghaiTech University, Shanghai, China.
His current research interests include electromagnetic nondestructive evaluation of structures in nuclear power plant and aircraft.

Authors:

Chenzhi Zhang ShanghaiTech University
Huan Chen China Nuclear Power Operation Technology Corporation, LTD.
Chaofeng Ye ShanghaiTech University