Analysis of complex differential eddy current transducer for deep flaws evaluation

In this paper, we propose a differential eddy current transducer dedicated for detecting and sizing deep surface flaws in thick materials. An analysis of the excitation parameters was carried out in order to obtain a good depth resolution of the transducer. Well-chosen parameters of the excitation allow to obtain nearly linear dependence of the output signal amplitude on the flaw depth or high depth resolution of the transducer. The transducer can be calibrated to a particular defect depth and can be utilised in automatic defect classification or gap depth sizing. The results of numerical simulations as well as measurements are presented.