Finite Element Simulation of Pulsed Remote Field Eddy Current Phenomenon

A system identification approach to the modelling of pulsed eddy-current systems

“…1). The output of the FIR model is defined by yðnÞ Z X T ðnÞWðnÞ; (5) and the error signal is eðnÞ Z dðnÞ K yðnÞ:…”

“…For certain applications, (inspection of multilayered structures found in aircraft, insulated pipelines or storage tanks) PEC instruments are commercially available [2][3][4]. Recent research has confirmed the applicability of pulsed remotefield eddy-current (PRFEC) technique to the inspection of thick ferromagnetic tubes [5][6][7]. However, much work regarding data analysis is still to be done in order to exploit the full potential of the PEC technique.…”

Analytical modelling in low-frequency electromagnetic measurements of steel casing properties

“…They give a phenomenological description of the physics of the measurements and suggest adequate space and frequency relations [3][4][5][6]. Numerical studies commonly rely on the finite element method (FEM) [9][10][11]. Another possibility is a system identification approach based on experimental results (''black box'') or FEM [12].…”

“…Through sensitivity analysis, we illustrate known effects of coil separation and excitation frequency on the measurements of the casing properties [4,[6][7][8][9][10][11]. We confirm the existence of two separate frequency bands of the pick-up voltage spectrum, which can be employed for simultaneous measurement of inner diameter and wall thickness using pulse excitation [8,10]. Furthermore, the model can be used for prediction of the system response to any excitation waveform at any distance from the exciter coil [10,12].…”

“…Regardless of the approach, these studies deal only with certain aspects of the space-frequency characteristic. What is in question, almost exclusively, is the so-called ''remote zone'' in the remote-field technique (exciter and pick-up coils separated by more than two tube diameters, and frequencies below 100 Hz) [9][10][11][12].…”