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Abstract Ownership costs of operational aircraft have increased steadily over the years. One of the major cost drivers is structural deterioration due to corrosion. Beyond the economics, finding and characterizing corrosion is essential for the continued airworthiness of aircraft fleets. To this end, the pulsed eddy current technique holds the potential of becoming the primary means of detecting corrosion in multilayered structures. Its wide-band frequency spectrum allows the determination of a large number of parameters, such as defect size and location. Pulsed eddy current is still considered an experimental nondestructive technique because of realistic inspection problems (e.g., probe tilting, protrusion of rivets, and thickness variations in adhesive and paint) have not been addressed in the past. Recent advances change this situation and allow pulsed eddy current to be a credible field technique. 相似文献
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Time-Frequency Analysis of Pulsed Eddy Current Signals 总被引:9,自引:0,他引:9
M. S. Safizadeh B. A. Lepine D. S. Forsyth A. Fahr 《Journal of Nondestructive Evaluation》2001,20(2):73-86
Detection and measurement of the material loss due to corrosion in aircraft fuselage lap splices are of great importance to life management of ageing aircraft. Pulsed eddy current (PEC) techniques have shown the potential to fully characterise these structures. However, variations in the probe lift-off, the interlayer gaps and material thinning produce similar PEC signals, making signal interpretation very difficult. This paper describes time-frequency analysis algorithms applied to pulsed-eddy current signals from lap-joint specimens containing simulated flaws. The effect of probe lift-off, interlayer gap, and material thinning on PEC signals is examined in three-dimensional space (amplitude-time-frequency). This study shows that the time-frequency analysis of PEC signals provides specific visual patterns that can be related to the interlayer gap, lift-off, and material loss. 相似文献
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Marie-Ève Davoust Laurent Le Brusquet Gilles Fleury 《Journal of Nondestructive Evaluation》2010,29(3):155-167
An eddy current technique is used to inspect the interface between air and a conductive material such as aluminum, which can
be covered with a non-conductive material. Hidden corrosion may appear inside the conductive material. This corrosion leads
to flaws whose shape varies greatly depending of the flaw. The proposed methodology addresses this problem by considering
the potential shapes as realizations of a random process. The goal of the proposed approach is not to find the exact shape
of the corrosion flaw but to estimate some of its dimensional parameters. The area and the dimension ratio of the shape have
been chosen because they depict the importance of the corrosion damage. 相似文献
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Effect of Pulsed Current TIG Welding Parameters on Pitting Corrosion Behaviour of AA6061 Aluminium Alloy 总被引:4,自引:0,他引:4
T. Senthil Kumar V. Balasubramanian M. Y. Sanavullah S. Babu 《材料科学技术学报》2007,23(2):223-229
Medium strength aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding process for aluminium alloy is frequently TIG (tungsten inert gas) welding due to its comparatively easier applicability and better economy.In the case of single pass TIG welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The use of pulsed current parameters has been found to improve the mechanical properties of the welds compared to those of continuous current welds of this alloy due to grain refinement occurring in the fusion zone. A mathematical model has been developed to predict pitting corrosion potential of pulsed current TIG welded AA6061 aluminium alloy.Factorial experimental design has been used to optimize the experimental conditions. Analysis of variance technique has been used to find out the significant pulsed current parameters. Regression analysis has been used to develop the model. Using the developed model pitting corrosion potential values have been estimated for different combinations of pulsed current parameters and the results are analyzed in detail. 相似文献
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G. Mook J. Gllner O. Kser B. Mook S. Schultze 《Materialwissenschaft und Werkstofftechnik》2003,34(2):225-231
Eddy current inspection for intergranular corrosion The paper focuses on fundamental investigations into eddy current detection of intergranular corrosion of nickel based alloys. After introducing this damage phenomenon and its results briefly the eddy current distribution is calculated. The experimental results confirm the suitability of the eddy current method for damage detection and provide features for quantitative analysis. 相似文献
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Technical Physics Letters - A multiparameter technique for pulsed eddy current testing is proposed, which allows one to conduct separate quantitative determination of more than seven parameters of... 相似文献
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建立了脉冲磁场激励下圆柱导体内瞬态涡流场的理论模型。实现了瞬态涡流场的快速计算。通过实例表明上述圆柱导体内瞬态涡流场的快速计算方法有效。 相似文献
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M. C. Petri T. Y. C. Wei D. S. Kupperman J. Reifman J. A. Morman 《Journal of Nondestructive Evaluation》2000,19(4):149-164
Eddy current techniques are extremely sensitive to the presence of axial cracks in nuclear power plant steam generator tube walls, but they are equally sensitive to the presence of dents, fretting, support structures, corrosion products, and other artifacts. Eddy current signal interpretation is further complicated by cracking geometries more complex than a single axial crack. Although there has been limited success in classifying and sizing defects through artificial neural networks, the ability to predict tubing integrity has, so far, eluded modelers. In large part, this lack of success stems from an inability to distinguish crack signals from those arising from artifacts. We present here a new signal processing technique that deconvolves raw eddy current voltage signals into separate signal contributions from different sources, which allows signals associated with a dominant crack to be identified. The signal deconvolution technique, combined with artificial neural network modeling, significantly improves the prediction of tube burst pressure from bobbin-coil eddy current measurements of steam generator tubing. 相似文献