Cracks are popular defects initiated in structural components and their accurate evaluation is very important to assure the reliability of various plants. The direct-current electrical potential difference method is known as one of the most effective methods for the evaluation of the cracks. In this paper, a method of three-dimensional identification of a semi-elliptical crack existing on the back surface of a conductive plate by the direct-current electrical potential difference method with a multiple-probe sensor is proposed. The geometrical condition of the crack was specified by six parameters, the surface and inward angles of the crack plane, θsur and θin, the length and depth of the crack, c and a, and the two-dimensional location of the crack center, (yc,zc), on the back surface. The identification was carried out based on the distribution of electrical potential difference on the surface of the plate measured with a sensor composed of grid-arranged multiple probes called the “multiple-probe sensor.” As an approximate cracked body and a quick analysis method were used, a number of repeated electrical potential field analyses necessary for the identification of the crack became possible within a practical time. The validity of the method was numerically confirmed by carrying out the identification based on the result of the finite element analysis. The proposed method could be extended to the online monitoring of a semi-elliptical crack initiated on the inner surface of tubular components by means of the multiple-probe sensor placed on the outer surface.

1.
Viswanathan
,
R.
, 2000, “
Life Management of High-Temperature Piping and Tubing in Fossil Power Plants
,”
ASME J. Pressure Vessel Technol.
0094-9930,
122
, pp.
305
316
.
2.
Viswanathan
,
R.
, and
Stringer
,
J.
, 2000, “
Failure Mechanisms of High Temperature Components in Power Plants
,”
ASME J. Eng. Mater. Technol.
0094-4289,
122
, pp.
246
255
.
3.
Yoo
,
Y. S.
, and
Ando
,
K.
, 2000, “
Circumferential Inner Fatigue Crack Growth and Penetration Behaviour in Pipe Subjected to a Bending Moment
,”
Fatigue Fract. Eng. Mater. Struct.
8756-758X,
23
, pp.
1
8
.
4.
Kawashima
,
F.
,
Igari
,
T.
,
Tokiyoshi
,
T.
,
Shiibashi
,
A.
, and
Tada
,
N.
, 2004, “
Micro-Macro Combined Simulation of the Damage Progress in Low-Alloy Steel Welds Subjected to Type IV Creep Failure
,”
JSME Int. J., Ser. A
1340-8046,
47
, pp.
410
418
.
5.
C. J.
Beavers
, ed., 1980,
The Measurement of Crack Length and Shape During Fracture and Fatigue
,
Engineering Materials Advisory Services
,
Warley, UK
, pp.
85
284
.
6.
Oppermann
,
W.
,
Hofstotter
,
P.
, and
Keller
,
H. P.
, 1997, “
Long-Term Installations of the DC-Potential Drop Method in Four Nuclear Power Plants and the Accuracies Thereby Obtained for Monitoring of Crack Initiation and Crack Growth
,”
Nucl. Eng. Des.
0029-5493,
174
, pp.
287
292
.
7.
Jegarl
,
S.
, 2000, “
Development of an Electric Potential Technique for Analyzing Pipe Thickness Configuration
,”
Proceedings of the ASME Pressure Vessels and Piping Conference
, Vol.
409
, pp.
203
208
.
8.
Gandossi
,
L.
,
Summers
,
S. A.
,
Taylor
,
N. G.
,
Hurst
,
R. C.
,
Hulm
,
B. J.
, and
Parker
,
J. D.
, 2001, “
The Potential Drop Method for Monitoring Crack Growth in Real Components Subjected to Combined Fatigue and Creep Conditions: Application of FE Techniques for Deriving Calibration Curves
,”
Int. J. Pressure Vessels Piping
0308-0161,
78
, pp.
881
891
.
9.
Chen
,
W.
,
Chen
,
J.
, and
Fang
,
H.
, 2002, “
A Theoretical Procedure for Detection of Simulated Cracks in a Pipe by the Direct Current-Potential Drop Technique
,”
Nucl. Eng. Des.
0029-5493,
216
, pp.
203
211
.
10.
Cerny
,
I.
, 2004, “
The Use of DCPD Method for Measurement of Growth of Cracks in Large Components at Normal and Elevated Temperatures
,”
Eng. Fract. Mech.
0013-7944,
71
, pp.
837
848
.
11.
Tada
,
N.
, 1992, “
Monitoring of a Surface Crack in a Finite Body by Means of Electrical Potential Technique
,”
Int. J. Fract.
0376-9429,
57
, pp.
199
220
.
12.
Tada
,
N.
,
Hayashi
,
Y.
,
Kitamura
,
T.
, and
Ohtani
,
R.
, 1997, “
Analysis on the Applicability of Direct Current Electrical Potential Method to the Detection of Damage by Multiple Small Internal Cracks
,”
Int. J. Fract.
0376-9429,
85
, pp.
1
9
.
13.
Tada
,
N.
,
Kitamura
,
T.
,
Ohtani
,
R.
, and
Nakayama
,
E.
, 1998, “
Evolution of Creep-Fatigue Damage in Type 304 Stainless Steel and Its Detection by Electrical Potential Method
,”
Acta Metall. Sin. (Engl. Lett.)
1006-7191,
11
, pp.
463
469
.
14.
Tada
,
N.
,
Hayashi
,
Y.
,
Kitamura
,
T.
, and
Ohtani
,
R.
, 1998, “
Analysis of Direct Current Potential Difference in a Multiple-Cracked Material
,”
JSME Int. J., Ser. A
1340-8046,
41
, pp.
372
379
.
15.
Tada
,
N.
,
Nakayama
,
E.
,
Kitamura
,
T.
, and
Ohtani
,
R.
, 2000, “
Analysis of Direct Current Potential Field Around Multiple Spherical Defects
,”
JSME Int. J., Ser. A
1340-8046,
43
, pp.
109
116
.
16.
Tada
,
N.
,
Okada
,
M.
, and
Iwamoto
,
J.
, 2007, “
Three-Dimensional Identification of Semi-Elliptical Surface Crack by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor
,”
ASME J. Pressure Vessel Technol.
0094-9930,
129
, pp.
441
448
.
17.
Tada
,
N.
, 2005, “
Evaluation of Multiple Through-Cracks With Random Angles by Direct Current Electrical Potential Difference Method
,”
Proceedings of the Third US-Japan Symposium on Advancing Applications and Capabilities
,
The American Society for Nondestructive and Testing
, pp.
451
457
.
18.
Tada
,
N.
, 2006, “
Evaluation of the Distribution of Multiple Circular Cracks with Random Radii and Angles by Direct Current Electrical Potential Difference Method
,”
Int. J. Fract.
0376-9429,
141
, pp.
49
62
.
19.
Hoct Systems Co., Ltd.
, 2004,
Manual of FEMLEEG
, Kyoto, Japan, in Japanese.
You do not currently have access to this content.