Abstract
Eddy current methods are used extensively in the nondestructive testing of aircraft structures and parts. One of the challenging problems in the inspection of aircraft structures is the detection of flaws in multilayer geometries in the vicinity of edges. Very often the large contribution to the signal from the edges masks the information related to the defects. This paper investigates the design of a new eddy current probe for eliminating the edge effect. A simple method to focus the field is devised using a combination of two coils. The total field distribution is controlled by choosing the coil geometry and coil currents appropriately. Both the magnitude and phase of the currents in the two coils are varied in order to obtain the desired flux pattern. The efficiency of these probe designs is demonstrated using finite element models. The probe parameters are optimized using finite element predictions. A probe built on the basis of this study is used to demonstrate experimentally the feasibility of the approach. (Author)