科研之友
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摘要
The pulsed eddy current technique (PECT) has proven to be quite effective in detecting sub-surface defects in non-ferromagnetic materials. However, due to the skin effect phenomenon and material properties, PECT has limited capabilities in detecting sub-surface defects in ferromagnetic materials. Magnetic saturation of the specimen is a useful way to overcome these problems. The present work employs three-dimensional (3D) finite element modelling to investigate the performance of PECT and magnetic saturation in detecting sub-surface defects in ferromagnetic steels. For this purpose, rectangular pitting defects with different depths are modelled on a 10 mm-thick steel plate. The model incorporates a probe with coaxially-coupled excitation and pick-up coils placed above a magnetised specimen with a constant lift-off. Then, transient signals obtained from different depths of defects are analysed and discussed. The simulation results indicate the effectiveness of the proposed technique in detecting sub-surface defects. Finally, the simulation results are verified by experimental tests.
- 出版日期2018-6
