In this study, the way to enhance the sensitivity of evaluating deep surface cracks by DCPD technique using four probes is considered. The potential drops across two-dimensional cracks having different depths are analyzed by the three-dimensional finite-element method. The effect of the distance between current input and output probes and the distance between measuring probes on the change in potential drops are analyzed for a wide range of crack depths. By extending the distance between current input and output probes, the change in potential drop with the change in the depth of deeper crack becomes large. But the voltage of potential drop becomes small to measure. Finally, the way to select the appropriate distances between the probes for the measuring sensor is shown from the viewpoints of sensitivity and the required current.

Issue Section:
Research Papers
Keywords:
surface cracks, crack detection, nondestructive testing, finite element analysis, electric potential, probes
Topics:
Fracture (Materials), Probes, Surface cracks, Sensors
1.
Johnson
,
H. H.
, 1965, “
Calibrating the Electric Potential Method for Studying Slow Crack Growth
,”
Mater. Res. Stand.
0025-5394,
5
(
1
), pp.
442
–
445
.
2.
Saka
,
M.
,
Oouchi
,
A.
, and
Abé
,
H.
, 1996, “
NDE of a Crack by Using Closely Coupled Probes for DCPD Technique
,”
ASME J. Pressure Vessel Technol.
0094-9930,
118
, pp.
198
–
202
.
Crossref
Search ADS
 
3.
Liu
,
H.
,
Saka
,
M.
,
Abé
,
H.
,
Komura
,
I.
, and
Sakamoto
,
H.
, 1999, “
Analysis of Interaction of Multiple Cracks in a Direct Current Field and Nondestructive Evaluation
,”
ASME J. Appl. Mech.
0021-8936,
66
, pp.
468
–
475
.
Crossref
Search ADS
 
4.
Venkatasubramanian
,
T. V.
, and
Unvala
,
B. A.
, 1984, “
An AC Potential Drop System for Monitoring Crack Length
,”
J. Phys. E
0022-3735,
17
, pp.
765
–
771
.
Crossref
Search ADS
 
5.
Dover
,
W. D.
, and
Monahan
,
C. C.
, 1994, “
The Measurement of Surface Breaking Cracks by the Electrical Systems ACPD/ACFM
,”
Fatigue Fract. Eng. Mater. Struct.
8756-758X,
17
(
12
), pp.
1485
–
1492
.
Crossref
Search ADS
 
6.
Clark
,
R.
, and
Dover
,
W. D.
, 1987, “
The Effect of Crack Closure on the Reliability of NDT Predictions of Crack Size
,”
NDT Int.
0308-9126,
20
(
5
), pp.
269
–
275
.
7.
Saka
,
M.
,
Hirota
,
D.
, and
Abé
,
H.
, 1996, “
Enhancement of Sensitivity of the Potential Drop Technique for Sizing a Crack by Using Closely Coupled Probes
,”
Proc. 14th World Conference on Non Destructive Testing
, New–Delhi,
ICNDT
,
Hamilton
,
3
, pp.
1659
–
1662
.
8.
Saka
,
M.
,
Hirota
,
D.
,
Abé
,
H.
, and
Komura
,
I.
, 1998, “
NDE of a 3-D Surface Crack Using Closely Coupled Probes for DCPD Technique
,”
ASME J. Pressure Vessel Technol.
0094-9930,
120
, pp.
374
–
378
.
Crossref
Search ADS
 
9.
Takeo
,
F.
, and
Saka
,
M.
, 2004, “
Advancement of the Closely Coupled Probes Potential Drop Technique for NDE of Surface Cracks
,”
Proc. 16th World Conference on Non Destructive Testing
, Montreal,
ICNDT
, Hamilton, CD-ROM, pp.
1
–
6
.
10.
Valdes
,
L. B.
, 1954, “
Resistivity Measurements on Germanium for Transistors
,”
Proc. IRE
0096-8390,
42
, pp.
420
–
427
.
Crossref
Search ADS
 
11.
Uhlir
,
A.
, Jr., 1955, “
The Potentials of Infinite Systems of Sources and Numerical Solutions of Problems in Semiconductor Engineering
,”
Bell Syst. Tech. J.
0005-8580,
34
, pp.
105
–
128
.
Crossref
Search ADS
 
12.
Yamashita
,
M.
, and
Agu
,
M.
, 1984, “
Geometrical Correction Factor for Semiconductor Resistivity Measurements by Four-Point Probe Method
,”
Jpn. J. Appl. Phys.
0021-4922,
23
(
11
), pp.
1499
–
1504
.
13.
Hayakawa
,
M.
,
Hamada
,
S.
,
Takeo
,
F.
, and
Saka
,
M.
, 2005, “
Development of Crack Depth Indicator for Deep Surface Crack
,”
Proc. of International Mechanical Engineering Congress and Exposition
, Orlando, ASME, New York, CD-ROM, pp.
1
–
5
.
Copyright © 2007
 by American Society of Mechanical Engineers
You do not currently have access to this content.