Development of a Bidirectional-Excitation Eddy-Current Sensor With Magnetic Shielding: Detection of Subsurface Defects in Stainless Steel

To reduce the effects of surface characteristics of materials and background noise of a magnetic excitation field, a new sensor with magnetic shielding was developed for eddy-current (EC) testing. Based on the analysis of EC theory, the performances of different cores, including air core, solid cylindrical ferrite core, hollow cylindrical ferrite core, and magnetic shielding ferrite core, were ana...