Thermography has proven to be one of the most effective approaches to detect cracks in conductive specimens over a relatively large area. Pulsed eddy current stimulated thermography is an emerging integrative nondestructive approach for the detection and characterization of surface and subsurface cracks. In this paper, heating behaviors of edge cracks, excited by pulsed eddy currents, are examined using numerical simulations. The simulations are performed using COMSOL multiphysics finite element method simulation software using the AC/DC module. The simulation results show that in the early heating stage, the temperature increases more quickly at the crack tip compared with other points on the sample. The results indicate that to maximize sensitivity, the response should be analyzed in the early stages of the heating period, no more than 100 ms for samples in which we are interested. The eddy current density distribution is changed with a variation in inductor orientation, but the crack tips remain the “hottest” points during the excitation period, which can be used for robust quantitative defect evaluation. Signal feature selection, transient temperature profile of the sample, and influence of the inductor orientation on the detection sensitivity for edge cracks are investigated. The work shows that positioning of the inductor, perpendicular to the crack line, results in the highest sensitivity for defect detection and characterization. The crack orientation can be estimated through the rotation of the linear inductor near the sample edge and the crack tips.

1.
Edwards
,
R. S.
,
Dixon
,
S.
, and
Jian
,
X.
, 2006, “
Characterisation of Defects in the Railhead Using Ultrasonic Surface Waves
,”
NDT Int.
0308-9126,
39
(
6
), pp.
468
475
.
2.
Li
,
Y.
,
Tian
,
G. Y.
, and
Ward
,
S.
, 2006, “
Numerical Simulations on Electromagnetic NDT at High Speed
,”
Insight—Non-Destructive Testing and Condition Monitoring
,
48
(
2
), pp.
103
108
. 0002-7820
3.
Shepard
,
S. M.
, 2007, “
Thermography of Composites
,”
Mater. Eval.
0025-5327,
65
(
7
), pp.
690
696
.
4.
Vasić
,
D.
,
Bilas
,
V.
, and
Ambruš
,
D.
, 2004, “
Pulsed Eddy-Current Nondestructive Testing of Ferromagnetic Tubes
,”
IEEE Trans. Instrum. Meas.
0018-9456,
53
(
4
), pp.
1289
1294
.
5.
Krishnapillai
,
M.
,
Jones
,
R.
,
Marshall
,
I. H.
,
Bannister
,
M.
, and
Rajic
,
N.
, 2006, “
NDTE Using Pulse Thermography: Numerical Modeling of Composite Subsurface Defects
,”
Compos. Struct.
0263-8223,
75
(
1–4
), pp.
241
249
.
6.
Wilson
,
J.
,
Tian
,
G. Y.
,
Abidin
,
I. Z.
,
Yang
,
S.
, and
Almond
,
D.
, 2010, “
Modelling and Evaluation of Eddy Current Stimulated Thermography
,”
Nondestr. Test. Eval.
1058-9759,
25
(
3
), pp.
205
218
.
7.
Jeong
,
S. Y.
,
Kim
,
B. C.
, and
Kim
,
Y. H.
, 2007, “
Defect Detection in a Cylinder Using an IR Thermographic Device and Point Heating
,”
2007 International Conference on Control, Automation and Systems
, Seoul, Korea, Oct. 17–20, pp.
2389
2392
.
8.
Avdelidis
,
N. P.
,
Hawtin
,
B. C.
, and
Almond
,
D. P.
, 2003, “
Transient Thermography in the Assessment of Defects of Aircraft Composites
,”
NDT Int.
0308-9126,
36
(
6
), pp.
433
439
.
9.
Bates
,
D.
,
Smith
,
G.
,
Lu
,
D.
, and
Hewitt
,
J.
, 2000, “
Rapid Thermal Non-Destructive Testing of Aircraft Components
,”
Composites, Part B
1359-8368,
31
(
3
), pp.
175
185
.
10.
Burrows
,
S. E.
,
Rashed
,
A.
,
Almond
,
D. P.
, and
Dixon
,
S.
, 2007, “
Combined Laser Spot Imaging Thermography and Ultrasonic Measurements for Crack Detection
,”
Nondestr. Test. Eval.
1058-9759,
22
(
2–3
), pp.
217
227
.
11.
Maldague
,
X.
, 2002, “
Introduction to NDT by Active Infrared Thermography
,”
Mater. Eval.
0025-5327,
6
(
9
), pp.
1060
1073
.
12.
Zenzinger
,
G.
,
Bamberg
,
J.
,
Dumm
,
M.
, and
Nutz
,
P.
, 2005, “
Crack Detection Using Eddytherm
,”
CP760, Review of Quantitative Nondestructive Evaluation
, Vol.
24
,
D. O.
Thompson
and
D. E.
Chimenti
, eds.,
American Institute of Physics
,
New York
.
13.
Vrana
,
J.
,
Goldammer
,
M.
,
Baumann
,
J.
,
Rothenfusser
,
M.
, and
Arnold
,
W.
, 2008, “
Mechanisms and Models for Crack Detection With Induction Thermography
,”
CP975, Review of Quantitative Nondestructive Evaluation
, Vol.
27
,
D. O.
Thompson
and
D. E.
Chimenti
, eds.,
American Institute of Physics
,
New York
.
14.
Netzelmann
,
U.
, and
Walle
,
G.
, 2008, “
Induction Thermography as a Tool for Reliable Detection of Surface Defects in Forged Components
,”
17th World Conference on Nondestructive Testing
, Shanghai, China, Oct. 25–28.
15.
Oswald-Tranta
,
B.
, and
Wally
,
G.
, 2006, “
Thermo-Inductive Surface Crack Detection in Metallic Materials
,”
Proceedings of the Ninth European Conference on NDT
, Berlin, Germany, Sept. 25–29, Paper No. We.3.8.3.
16.
Wally
,
G.
, and
Oswald-Tranta
,
B.
, 2007, “
The Influence of Crack Shapes and Geometries on the Result of the Thermo-Inductive Crack Detection
,”
Proc. SPIE
0277-786X,
6541
, p.
654111
.
17.
Walle
,
G.
, and
Netzelmann
,
U.
, 2006, “
Thermographic Crack Detection in Ferritic Steel Components Using Inductive Heating
,”
Proceedings of the Ninth ECNDT
, Berlin, Germany, Sept. 25–29, Paper No. Tu.4.8.5.
18.
Li
,
Y.
,
Theodoulidis
,
T.
, and
Tian
,
G. Y.
, 2007, “
Magnetic Field-Based Eddy-Current Modeling for Multilayered Specimens
,”
IEEE Trans. Magn.
0018-9464,
43
(
11
), pp.
4010
4015
.
19.
Silvester
,
P.
, and
Ferrari
,
R. L.
, 1996,
Finite Elements for Electrical Engineers
,
3rd ed.
,
Cambridge University Press
,
Cambridge
.
20.
Wilson
,
J.
,
Tian
,
G. Y.
,
Abidin
,
I. Z.
,
Yang
,
S.
, and
Almond
,
D.
, 2010, “
Pulsed Eddy Current Thermography: System Development and Evaluation
,”
Insight—Non-Destructive Testing and Condition Monitoring
,
52
(
2
), pp.
87
90
. 0002-7820
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