Detecting non-magnetic conducting flat plates with pulsed Remote Eddy Current Field technique

Abstract

Non-magnetic metal plates are widely used in aviation and industry areas. The detection of cracks in thick-plate structures, such as multilayered structures of aircraft fuselage, has been challenging in Nondestructive Evaluation (NDE) societies. Remote Field Eddy Current (RFEC) technique has shown advantages of deep penetration and high sensitivity to anomalies deeply buried. However, RFEC technique is mainly used to evaluate ferromagnetic tubes. There are many problems which should be tackled before this technique is expanded and applied to the inspection of non-magnetic conductive plates. In this paper, Pulsed Remote Field Eddy Current (PRFEC) for detection of non-magnetic conducting plates is investigated. The principle of PRFEC is analyzed firstly. The influence of different UTC materials to detecting ability are analyzed. The defect detection sensitivity and the detectability to thick plates by using three probes are also analyzed and compared. Simulation results show that the UTC material should be same with the plate in detecting of non-magnetic specimen and the probe with a ferrite yoke has highest detectability. The conclusions derived from the simulation study are also validated by experiments.