Tube inspection with a rotating probe
Summary
Specimen
A tube made in inconel (conductivity of 1 MS.m-1 and a relative permeability of 1) is inspected with a rotating probe. The tube has an external diameter of 18.99 mm, an internal radius of 8.32 mm, a thickness of 1.175 mm and measures 50 mm length.
Probe
The probe is a cylindrical coil which geometrical characteristics are defined on the following figure. The acquisition is carried out in an absolute mode at 5 different frequencies: 25, 50, 100, 150 and 200 kHz.
Defect
The tube contains a longitudinal through wall notch of 12.2 mm length notch, with the same thickness as the tube, ie 1.175 mm, and with an angular extension of 0.585°.
Comparisons between CIVA and the experiment
The experimental measurements have been realized with an impedancemeter, it has also not been necessary to calibrate the results before the comparison.
Lissajous curves are drawn and the amplitudes, phases, real and imaginary parts as a function of the scanning are represented on the figures below for the frequencies 25, 50, 100, 150 et 200 kHz . A good agreement between experiment and simulation is observed.
Then, the amplitude and phase values are gathered in a table and the difference between acquisitions and CIVA simulations are calculated. The small differences confirm the good agreement between CIVA and experiments.
25 kHz
50 kHz
100 kHz
150 kHz
200 kHz
Finally, on two synthesis graphs are superimposed CIVA and acquistion curves. The first one shows the evolution of the amplitude as a function of the frequency, and the second one represents the evolution of the phase still as a function of the frequency.
The good agreement between CIVA and the experiment is confirmed again by this graphs.
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