Structural optimization of 2-D array probe for alternating current field measurement

A double U-shaped orthogonal inducer for the alternating current field measurement (ACFM) is presented, which could extend the limitation of the direction of tested cracks and decrease the loss of magnetic flux compared to the single rectangular inducer. The structure of the testing probe was optimized to meet the expectations of the pointwise magnetic field measurement and to decrease every group of coils’ space by orthogonally winding method, and the two-dimensional (2-D) ACFM probe array was designed. The detection precision and lift-off effect of the 2-D ACFM probe array were experimentally studied. The results show that the relative error of this probe is less than 10%, and it could suppress the lift-off disturbance effectively, which makes this 2-D ACFM probe array to be insensitive to lift-off and unable to meet the engineering expectations.