Defect detection and classification using a SQUID based multiple frequency eddy current NDE system

EPRI is involved in a multi-year program to test, evaluate, and develop a field-deployable eddy current NDE system for life assessment of blade coatings for advanced gas turbines. An eddy current system was assembled and tested on service-aged 7FA first stage blade buckets, which were coated with GT 33+ duplex metallic coatings. Testing of transverse cutout sections showed presence of normal coating, coating degradation due to β-phase depletion, and cracked coatings with some cracks penetrating into the GTD-111 substrate. By plotting normalized multiple-frequency eddy current coil impedance values, the eddy current technique was able to assess and provide the following coating and airfoil conditions: 1) normal coating; 2) degraded coating; 3) cracked coating; and 4) possible corrosion of GTD-111 substrate. Using a built-in three-layer inversion program, conductivity values of topcoat, bond coat, and GTD-111 substrate were also estimated using aged blade buckets.

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Exact First Order Finite Element Modeling for Eddy Current NDE

Research in Nondestructive Evaluation ◽

10.1080/09349849108968051 ◽

1991 ◽

Vol 3 (1) ◽

pp. 235-253 ◽

Cited By ~ 1

Author(s):

L. D. Philipp ◽

Q. H. Nguyen ◽

D. D. Derkacht ◽

D. J. Lynch ◽

A. Mahmood

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Eddy Current ◽

Element Modeling ◽

First Order ◽

Eddy Current Nde

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Dual-frequency eddy-current NDE based on high-Tc rf SQUID

Physica C Superconductivity ◽

10.1016/s0921-4534(02)01322-9 ◽

2002 ◽

Vol 383 (3) ◽

pp. 223-226 ◽

Cited By ~ 24

Author(s):

D.F He ◽

M Yoshizawa

Keyword(s):

Eddy Current ◽

Dual Frequency ◽

High Tc ◽

Eddy Current Nde ◽

Rf Squid

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APPLICATION OF MODEL-BASED INVERSION TO EDDY-CURRENT NDE OF HEAT-EXCHANGER TUBING

10.1063/1.3114329 ◽

2009 ◽

Author(s):

Harold A. Sabbagh ◽

John C. Aldrin ◽

R. Kim Murphy ◽

Elias H. Sabbagh ◽

Donald O. Thompson ◽

...

Keyword(s):

Heat Exchanger ◽

Eddy Current ◽

Model Based ◽

Eddy Current Nde

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Flexible Differential Butterfly-Shape Eddy Current Array Sensor for Defect Detection of Screw Thread

IEEE Sensors Journal ◽

10.1109/jsen.2021.3093550 ◽

2021 ◽

pp. 1-1

Author(s):

Saibo She ◽

Youzhi Liu ◽

Shijing Zhang ◽

Yizhang Wen ◽

Zhongji Zhou ◽

...

Keyword(s):

Defect Detection ◽

Eddy Current ◽

Screw Thread ◽

Array Sensor

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A REVIEW ON EDDY CURRENT THERMOGRAPHY TECHNIQUE FOR NON-DESTRUCTIVE TESTING APPLICATION

Jurnal Teknologi ◽

10.11113/.v78.7656 ◽

2016 ◽

Vol 78 (11) ◽

Author(s):

N. S. Rusli ◽

I. Z. Abidin ◽

S. A. Aziz

Keyword(s):

Defect Detection ◽

Eddy Current ◽

Infrared Camera ◽

Heat Diffusion ◽

Non Destructive Testing ◽

Destructive Testing ◽

Quantitative Characterisation ◽

Optimum Heating ◽

Non Destructive ◽

Eddy Current Heating

Eddy current thermography is one of the non-destructive testing techniques that provide advantages over other active thermography techniques in defect detection and analysis. The method of defect detection in eddy current thermography has become reliable due to its mode of interactions i.e. eddy current heating and heat diffusion, acquired via an infrared camera. Such ability has given the technique the advantages for non-destructive testing applications. The experimental parameters and settings which contribute towards optimum heating and defect detection capability have always been the focus of research associated with the technique. In addition, the knowledge and understanding of the characteristics heat distribution surrounding a defect is an important factor for successful inspection results. Thus, the quantitative characterisation of defect by this technique is possible compared to the conventional non-destructive which only acquired qualitative result. In this paper, a review of the eddy current thermography technique is presented which covers the physical principles of the technique, associated systems and its applications. Works on the application of the technique have been presented and discussed which demonstrates the ability of eddy current thermography for non-destructive testing of conductive materials.

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