In this paper, the modified reference stress method is introduced to estimate the C* integral for collinear creep cracks near the mismatching bimaterial interface (MBI) and the process that leads to these solutions is also presented. The interacting factors for creep cracks near the MBI are defined and the influences of different creep exponents and mismatching factors (MF) on creep interacting effect are studied. Results show that if two inner creep crack tips get closer, the interacting effect of creep cracks near the MBI will become much stronger. Under the same condition, the interacting factors of the creep cracks in materials with higher creep exponent are larger than that of the creep cracks in materials with lower creep exponent. For the same crack location, C* integral decreases with the increase of MF. Two novel dimensionless parameters are proposed to characterize the rationality of combination rules of ASME, API 579, and R6 codes for the interacting effect for creep collinear cracks near the MBI. With the proposed parameter, the nonconservative ranges to use the combination rules of ASME, API 579, and R6 codes are rediscussed and presented.

References

References
1.
Liu
,
D. H.
,
Li
,
H. S.
, and
Liu
,
Y. H.
,
2015
, “
Numerical Simulation of Creep Damage and Life Prediction of Superalloy Turbine Blade
,”
Math. Probl. Eng.
,
2015
, p.
732502
.
2.
ASME
,
2007
,
Boiler and Pressure Vessel Code Section XI
,
American Society of Mechanical Engineers
,
New York
.
3.
API
,
2007
, “
Fitness-for-Service
,” Sec. 9, American Petroleum Institute, Washington, DC, Standard No. API 579-1/ASME FFS-1.
4.
British Energy Generation Ltd.
,
2001
, “
Assessment of the Integrity of Structures Containing Defects
,” R6 Revision 4,
British Energy Generation Ltd
.,
Gloucester, UK
, pp.
155
169
.
5.
Koiter
,
W. T.
,
1959
, “
An Infinite Row of Collinear Cracks in an Infinite Elastic Sheet
,”
Arch. Appl. Mech.
,
28
(
1
), pp.
168
172
.
6.
Yokobori
,
T.
,
Uosumi
,
M.
, and
Ichikawa
,
M.
,
1970
, “
Interaction Between Overlapping Parallel Elastic Cracks
,”
J. Jpn. Soc. Strength
,
6
(
2
), pp.
39
50
(in Japanese).
7.
Theocaris
,
P. S.
,
1972
, “
Interaction Between Collinear Asymmetric Cracks
,”
J. Strain Anal. Eng.
,
7
(
3
), pp.
186
193
.
8.
Ratwani
,
M.
, and
Gupta
,
G. D.
,
1974
, “
Interaction Between Parallel Cracks in Layered Composites
,”
Int. J. Solids Struct.
,
10
(
7
), pp.
701
708
.
9.
Gdoutos
,
E. E.
,
1980
, “
Interaction Between Two Equal Skew-Parallel Cracks
,”
J. Strain Anal. Eng.
,
15
(
3
), pp.
127
136
.
10.
Shih
,
C. F.
, and
Asaro
,
R. J.
,
1989
, “
Elastic–Plastic Analysis of a Collinear Array of Cracks on a Bimaterial Interface
,”
Math. Sci. Eng. A
,
107
, pp.
145
157
.
11.
Nilsson
,
K. F.
,
1996
, “
Elasto-Plastic Models for Interaction Between a Major Crack and Multiple Small Cracks
,”
FAA-NASA Symposium on the Continued Airworthiness of Aircraft Structures
,
Atlanta, GA
, Aug. 28–30, Vol.
1
, pp.
197
224
.
12.
Moussa
,
W. A.
,
Bell
,
R.
, and
Tan
,
C. L.
,
1999
, “
The Interaction of Two Parallel Non-Coplanar Identical Surface Cracks Under Tension and Bending
,”
Int. J. Pressure Vessels Piping
,
76
(
3
), pp.
135
145
.
13.
Roy
,
A.
, and
Chatterjee
,
M.
,
1994
, “
Interaction Between Coplanar Elliptic Cracks—I. Normal Loading
,”
Int. J. Solids Struct.
,
31
(
1
), pp.
127
144
.
14.
Kamaya
,
M.
, and
Totsuka
,
N.
,
2002
, “
Influence of Interaction Between Multiple Cracks on Stress Corrosion Crack Propagation
,”
Corros. Sci.
,
44
(
10
), pp.
2333
2352
.
15.
Si
,
J.
,
Xuan
,
F. Z.
, and
Tu
,
S. T.
,
2008
, “
A Numerical Creep Analysis on the Interaction of Twin Semi-Elliptical Cracks
,”
Int. J. Pressure Vessels Piping
,
85
(
7
), pp.
459
467
.
16.
Xuan
,
F. Z.
,
Si
,
J.
, and
Tu
,
S. T.
,
2009
, “
Evaluation of C* Integral for Interacting Cracks in Plates Under Tension
,”
Eng. Fract. Mech.
,
76
(
14
), pp.
2192
2201
.
17.
Xuan
,
F. Z.
,
Si
,
J.
, and
Tu
,
S. T.
,
2010
, “
Rules for the Assessment of Interacting Cracks Under Creep Conditions
,”
ASME J. Pressure Vessel Technol.
,
132
(1), pp.
1
7
.
18.
Budden
,
P. J.
, and
Curbishley
,
I.
,
2000
, “
Assessment of Creep Crack Growth in Dissimilar Metal Welds
,”
Nucl. Eng. Des.
,
197
, pp.
13
23
.
19.
Assire
,
A.
,
Michel
,
B.
, and
Raous
,
M.
,
2001
, “
Creep Crack Initiation and Creep Crack Growth Assessments in Welded Structures
,”
Nucl. Eng. Des.
,
206
(
1
), pp.
45
56
.
20.
Xuan
,
F. Z.
,
Tu
,
S. T.
, and
Wang
,
Z. D.
,
2004
, “
C* Estimation for Cracks in Mismatched Welds and Finite Element Validation
,”
Int. J. Fract.
,
126
(
3
), pp.
267
280
.
21.
Lei
,
Y.
, and
Ainsworth
,
R. A.
,
1997
, “
A J Integral Estimation Method for Cracks in Welds With Mismatched Mechanical Properties
,”
Int. J. Pressure Vessels Piping
,
70
(
3
), pp.
237
245
.
22.
ASTM
,
2013
, “
Standard Test Method for Measurement of Creep Crack Growth Times and Rates in Metals
,”
ASTM
,
Philadelphia, PA
, Standard No. E1457-13.
23.
Landes
,
J. D.
, and
Begley
,
J. A.
,
1976
, “
A Fracture Mechanics Approach to Creep Crack Growth
,”
ASTM STP, Vol.
590
, pp.
128
148
.
24.
Ainsworth
,
R. A.
,
1984
, “
The Assessment of Defects in Structures of Strain-Hardening Material
,”
Eng. Fract. Mech.
,
19
(
4
), pp.
633
642
.
25.
Lee
,
K. H.
,
Kim
,
Y. J.
,
Yoon
,
K. B.
,
Nikbin
,
K.
, and
Dean
,
D.
,
2010
, “
Quantification of Stress Redistribution Due to Mismatch in Creep Properties in Welded Branch Pipes
,”
Fatigue Fract. Eng. Mater. Struct.
,
33
(
4
), pp.
238
251
.
26.
Kim
,
Y. J.
,
Koçak
,
M.
,
Ainsworth
,
R. A.
, and
Zerbst
,
U.
,
2000
, “
SINTAP Defect Assessment Procedure for Strength Mis-Matched Structures
,”
Eng. Fract. Mech.
,
67
(
6
), pp.
529
546
.
27.
Ainsworth
,
R. A.
,
Bannister
,
A. C.
, and
Zerbst
,
U.
,
2000
, “
An Overview of the European Flaw Assessment Procedure SINTAP and Its Validation
,”
Int. J. Pressure Vessels Piping
,
77
(
14
), pp.
869
876
.
28.
Lei
,
Y.
,
2004
, “
J-Integral and Limit Load Analysis of Semi-Elliptical Surface Cracks in Plates Under Tension
,”
Int. J. Pressure Vessels Piping
,
81
(
1
), pp.
21
30
.
29.
Simulia Corp.
,
2008
, abaqus User's Manual, Version 6.8, Dassault Systems, Waltham, MA.
30.
Kim
,
Y. J.
, and
Schwalbe
,
K. H.
,
2001
, “
Mismatch Effect on Plastic Yield Loads in Idealized Weldments: I. Weld Center Cracks
,”
Eng. Fract. Mech.
,
68
(
2
), pp.
163
182
.
31.
Murakami
,
Y.
, and
Hasebe
,
N.
,
2001
,
Stress Intensity Factors Handbook
,
Elsevier Science
,
Oxford, UK
.
32.
Liu
,
B.
,
Kimoto
,
H.
, and
Kitagawa
,
H.
,
1996
, “
Elastic–Plastic Analysis of a Crack Parallel to the Interface
,”
Eng. Fract. Mech.
,
53
(
4
), pp.
607
623
.
33.
Saxena
,
A.
,
1991
, “
Creep Crack Growth in High Temperature Ductile Materials
,”
Eng. Fract. Mech.
,
40
(
4
), pp.
721
736
.
You do not currently have access to this content.