飛機多層結(jié)構(gòu)的多頻渦流檢測

?1?2?6435?1?2?6435 ?9?0?-? ?0?- ?0? ?-?0?5? ?0?- ?0?-? ?0 ? ?-?0?I? ?0?0? ?- ?0 ?0 ?0 ?6?0?-? ?0?0? ?- ? ?- ?u?0?0?0? Multifrequency eddy current inspection of multilayered structures in aircrafts Abstract:!With the rapid development of aviation industry in recent years, the aviation safety is more and more important to us. In both military aviation and civil aviation field, how to make the preventive maintenance and prevent mechanical failure in operation of aircrafts, is particularly important. Especially those overage aircrafts beyond the original design life (20 to 25 years) are still in service, they are vulnerable to the influence of corrosion damage and fatigue crack. How to be efficiently and make accurate detection of these defects, which endanger the property and safety of life on board? One of the methods is multi-frequency eddy current testing method. Its easy to produce fatigue crack near the rivets in riveting multi-layer structures, prone to corrosion defects between the layers. Firstly, this paper introduces the principle of multi- frequency eddy current inspection technology. According to the questions mentioned above, we build the experimental platform to simulate multi-level structure in aircrafts. Secondly, Using double-frequency eddy current detector to detect the simulated multilayer structure, discusses the differences and characteristics of single and multi-frequency eddy current testing, analyzes the advantages of multi-frequency eddy current testing in multilayer structure detection. Equipment produce current in different frequency and detect by one eddy current probe , various frequency signals can detect defects in different depth of multilayer structure.The results show that multi-frequency eddy current testing realize the effective defects. Multi-frequency eddy current testing eliminates noisy signal caused by fasteners, interlayer and air gap, enhance the flaw signal. It has great advantages in detection of interior of the aircraft skin. The testing practice and the conclusion of this article can be used for multi-frequency eddy current testing technology in the actual detection. Keyword: Multi-frequency eddy current Corrosion defects Riveting multi-layer structures Crack defects. ?q?r?q?r? ?9? ?2 ? ?9? ? ?2 ?9? ?2 ? ?9? ? ?2 ?2?Phasec2200 ?I? ?2 11?0?- 21?0?- 31?0?0?- 41?- 51?0?- ? ? ? 9? ?2? ? ? 9? ?2 11?0?0?- 20xx.3.09320xx.4.10 2. ?0?- 20xx.4.1132015.4.20 31?0?- 20xx.4.21320xx.4.25 41?- 20xx.4.26320xx.5.16 51?0?- 20xx.5.17320xx.5.31 61?0?- 20xx.6.01320xx.6.06 71?9?0?- 20xx.6.07320xx.6.26 ? ? ? ? ? ? ?2? ? ? ? ? ? ?2 1 J. A. Bieber, S. K. Shaligram, J. H. Rose, J. C. Moulder. Time-gating of Pulsed Eddy Current Signals for Defect Characterization and Discrimination in Aircraft Lap-JointsJ. 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NDT&E International, 2002, (36): 37-41. 7 LIBBY H LtIntroduction to electromagnetic nondestructive test methodswMx t New York:John WileypSons Inc ,1971t 8 Gui Yun Tian, Ali Sophian. Defect classification using a new feature for pulsed eddy current SensorsJ. NDT&E International, 2005(38): 77-82. 9 Ali Sophian. Characterization of Surface and Sub-surface Discontinuities in Metals Using Pulsed Eddy Current SensorsC. Thesis,the University of Huddersfield in partial fulfilment of the requirements for the degree of Doctor of Philosophy(The United Kingdom), 2003. 10 G. Y. Tian, Y. Li and C. Mandache. Study of Lift-Off Invariance for Pulsed Eddy-Current SignalsJ. IEEE Transaction on Magnetics, 2009, 45(1): 184-191. ?I?89?I?89? ? 2 ?2?xx?)?xx? ? 2 ? 2 ?I? 2 ? ? 2 ?2?xx?)?xx? ? 2 ? 2 ?I? 2 ? 1 ?! ? ? ?! ?(?“? ? ?! ?) ? )! ? ? )! ? ? )! 2 ? (? ? ?! (?(? ? ?! (?)? ? ,! (? ? -! (? ? .! 3 ? )? ? /! )?(? ? ?! )?)? ? ?(! )? ? ?)! 4 ? ? ? ?! ?(? ? ?! ?)? ? ?,! 5 ? ? ? ?-! ?(? ? ?/! ?)? ? (?! 6 ? ,? ? 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