Elliptical flaw

SPECIMEN

The inspected specimen is a plate of 1.27 mm thickness, in aluminium, conductivity of 18 MS.m-1 and relative permeability of 1.

Plate modeled in CIVA

PROBE

The probe is made out of a cylindrical coil at double function which geometrical properties are gathered on the figure below that shows the panel in CIVA allowing the definition of those properties. The acquisition is done at 100 kHz, with 100 mA in injection and reception in absolute mode.

Geometrical properties of the probe

Flaw

The specimen has a non-through elliptical defect emerging on surface, as drawn on figure below.

High and thickness of the elliptical defect present in the flat piece to inspect

EXPERIMENT/SIMULATION COMPARISONS

The experimental measurements have been realized with an impedancemeter, it has also not been necessary to calibrate the results before the comparison.

The figure below represents the C-scans obtained with the experiment and CIVA. They look similar.

Experimental C-scans (top) and obtained with CIVA (bottom) of real part (left) and imaginary part (right)

Amplitudes, phases, real and imaginary parts as a function of the scanning are compared on  figures below. A good agreement is observed between experiments and simulations.

 

Amplitude/phase curves comparisons (top), real/imaginary (bottom), horizontal (left) and vertical (right) cuts.

Here below Lissajous curves show a good agreemnt between simulations and experiment, 

Lissajous curves in impedance plane, horizontal cut (left) and vertical cut (right)

Finally, the table below gathers ampltudes and phases values and confirms the very low gap between experiment and simulation, less than 1 dB.

Maximal amplitudes values and corresponding phases, and discrepancies between CIVA and experiment (references: experimental values). 

 

 

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