Eddy Current Imaging Technique for Quantitative Analysis of Defects in Aircraft Components

Abstract

Aircraft industry’s concern is primarily in the area of safety of components and structures and it is extremely important to constantly evaluate and monitor the structures and systems for defects and anomalies noninvasively, thereby preventing unplanned outages and shutdowns as also catastrophes. To accomplish this, different nondestructive testing techniques have been in use since decades. Each technique is unique by itself and has its associated advantages and limitations; a suitable NDT technique for a particular case has to be selected depending on the type of material, structure and defect damage. Eddy current technique has been used in the evaluation of aircraft components and metallic structures to detect and quantify surface and subsurface defects like cracks, particularly in high stress-concentration regions like riveted and/or bolted joints. While imaging a defect using ultrasonic methods is quite common, eddy current imaging is currently gaining ground. The approach used in this work for detection and quantification of an intentionally introduced crack in a steel plate is to image using eddy current technique. The data obtained was used to generate an image of the defect which was subsequently quantified in terms of length and width. The results obtained are quite encouraging and can be treated as a precursor for wider use of eddy current imaging technique.

Keywords: Eddy current imaging, nondestructive testing, defect quantification, impedance