11081310傅禹-论文终稿.pdf

1 1 2 6435 2 6435 u u u 9 0 0 0 0 5 0 0 0 0 I 0 0 0 0 0 6 0 0 0 u 0 0 0 Multi frequency eddy current inspection of multilayered structures in aircrafts Student Name Fu Yu Classu110813 Supervisor Fu Yuewen 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 It s 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 Signature of Supervisor q r q r 9 9 2 2 9 9 2 2 2 Phasec2200 I 2 11 0 21 0 31 0 0 41 51 0 9 9 2 2 11 0 0 2015 3 0932015 4 10 2 0 2015 4 1132015 4 20 31 0 2015 4 2132015 4 25 41 2015 4 2632015 5 16 51 0 2015 5 1732015 5 31 61 0 2015 6 0132015 6 06 71 9 0 2015 6 0732015 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 Joints J Review of Progress in QNDE 1997 16B 1915 1921 2 SMITH R A HUGO G R Deep corrosion and crack detection in aging aircraft using transient eddy current NDE J Insight 2001 43 1 u14 24 3 J A Bieber S K Shaligram J H Rose et al Time gating of pulsed eddy current signals for defect characterization and discrimination in aircraft 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