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Optimization of the Flux Distribution in Magnetic Flux Leakage Testing

Many factors cause degeneration of the measured signal in magnetic flux leakage (MFL). One of these factors is non-uniformity of the magnetic flux inside the sample under test. Uniformity of the magnetic flux results in smoother and more predictable signals from various discontinuity types and also a reduction in the eddy current distortions induced because of the movement of the magnetizing yoke. The goal of this research is to find a near-optimal length for the magnetizing yoke. Toward this end, yokes with different lengths are simulated with the finite element method and the quality of the distribution of the flux lines inside the sample is studied. In this way a criterion for optimization of the length of the yoke is presented. Lest the optimization process deteriorate the discontinuity detection performance, simulating various discontinuities, the sensitivity of the system was studied for three different yoke lengths: optimal length; shorter length; and longer length.

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