Investigation of the magnetic field response from eddy current inspection of defects
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Eddy current testing is one of the most widely used methods in non-destructive testing for the inspection of conductive materials. Numerical modelling of eddy current testing has emerged as an important approach alongside experimental studies. This paper investigates an application of numerical modelling and experimental study as a means of the quantitative non-destructive evaluation (QNDE) of defects in conductive samples. There are two methods of measuring eddy current response, more commonly by measuring the change in impedance of the eddy current probe coil, or as used in this work, by measuring the change in magnetic field directly using magnetic field sensors such as superconducting quantum interference devices, giant magneto resistance, or as in this case Hall sensors. Specifically, measurements made using an eddy current probe containing an excitation coil and a Hall sensor, experimentally obtained using an X–Y scanner table, are compared with a numerical (finite element method) model. The discrepancies between the experimental tests and the numerical models have been analysed and explained, which is an important factor in engineering applications of QNDE.
KeywordsEddy current Non-destructive testing FEM Magnetic field Scanning
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