Pulsed eddy current non-destructive evaluation based on coupled electromagnetic quantities method

This paper proposes a semi-analytical model for Pulsed Eddy Current Non-Destructive Evaluation (PEC-NDE) based on the Coupled Electromagnetic Quantities Method (CEQM). The proposed formulation is developed from coupled electric circuit's approach in which the Crank Nicholson formula is used to derive the transient behavior. The computational model makes use of current excitation allowing the determination of the sensor voltage in the case of an axisymmetric device. The feature of the variation of voltage provides information on the electromagnetic and geometrical properties of the device. So, the second peak of voltage variation (SPVV) and second ratio between the minimum and maximum (RMM2) are used to determine these properties. The proposed model is validated by comparison with Fourier reconstitution obtained from measurements on one hand and with finite element calculations on the other hand. The developed model, associated to an inversion technique, is applied to evaluate the lift-off and the work piece thickness.