Optimization of eddy-current sensor for multifrequency systems

The use of fractional order derivatives for eddy current non-destructive testing

“…In this work it is shown, that relatively simple mathematical models containing fractional order derivatives can be a convenient and "flexible" tool for approximation of frequency characteristics when massive multi-frequency excitation and spectrogram eddy current method (MMFES) [11,12] is applied. The frequency characteristics of the transducer depend on defect size, shape and depth.…”

“…A massive multi-frequency excitation and spectrogram eddy current method (MMFES) was presented in some publications [11,12] as a very effective tool for inspection of conducting materials. This method allows identification of defects using a frequency characteristic of the transducer, which is affected by the defect.…”

“…Therefore, the parametrized frequency characteristic allows for precise defect recognition. In the previous works [11,12] coefficients of approximating function of the form (18) were used for the defect identification. In current work, the model based on fractional derivatives (16) is proposed.…”

Evaluation of Stress Loaded Steel Samples Using Selected Electromagnetic Methods

“…It contains four excitation coils (A, B, C, D) and a single search coil (S) mounted on a ferrite core (F). The probe construction is the same as presented in [6]. In case of stress loaded samples examination, the most important factor is a high spatial resolution of the transducer.…”

“…In case of stress loaded samples examination, the most important factor is a high spatial resolution of the transducer. Therefore, taking into account optimisation results achieved in [6] the distance between transducer's columns was set to 1.5 mm. The other dimensions (having minor influence on probe performance) were assumed in this way, that proportions of the original transducer [6] were preserved.…”