USING FINITE ELEMENT METHOD TO OPTIMIZE MAGNETIC FLUX LEAKAGE TESTING
Li Luming Zhang Jiajun Li Zhenxing Shao Xiaoyan NDT Lab. Mechanical Department, Tsinghua University Beijing, P. R. China
Keywords: magnetic flux leakage testing (MFL), finite element method (FEM), lift-off, reliability, sensitivity
ABSTRACT
Finite element method (FEM) is used to study the relationship of the component inner magnetic field strength, lift-off of sensor and the By component of magnetic flux leakage (MFL) of surface crack of parts in this paper. The detailed data and curves are given. Then the affects of component magnetic field strength and lift-off to the MFL are discussed. The derivates of component inner magnetic field strength and lift-off affect functions are compared. It's found that the derivate of component inner magnetic field strength function is a increased function but the lift-off's is a decreased one. Their curves are given and intersection point found too. These results are verified by experimental data. All the works above are the important reference and can be used to choose and optimize the testing parameters in practical MFL testing. The effect of lift-off is studied from testing reliability in this paper. The error data are given when the lift-off sensor undulates up and down in a range of +/-0.05 mm and the error curve is developed. These data show: For the same up and down undulation, the curves aren't symmetry. In the same undulated range, the lift-off is the larger, the error the smaller. Based on these results, a new viewpoint is developed that the lift-off isn't the smaller the better when the testing sensitivity is fulfilled.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 3, pages 1589 - 1592 Publisher:Ashgate Publishing Company
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