Low cycle fatigue tests and finite element (FEM) analysis were conducted using 100A pipe bend specimens made of STPT410 carbon steel with and without local wall thinning local wall thinning was machined on the inside of the elbow and was prepared at extrados, crown, and intrados. The parameters of the wall thinning were same (the wall thinning ratio = 0.5, the wall thinning angle = 180 deg, and the wall thinning length = 100 mm) in the all test cases. The pipe bend specimens were subjected to the prescribed cyclic in-plane bending displacement with constant internal pressure of 0–12 MPa. Also, low cycle fatigue tests using sound pipe bend specimens were carried out for comparison. According to the test results, low cycle fatigue strength of wall thinned pipe bend specimens was not so different, regardless of location of wall thinning. Low cycle fatigue strength of the pipe bend specimens was beneath the best fit fatigue curve and its reason can be explained quantitatively by a proposed cumulated damage rule introducing ductility exhaustion considering multi-axial stress state. The validity of the new proposed cumulative damage rule was also confirmed by the another sample analysis using other reference data obtained by pre-overloaded in-plane cyclic bending tests.

References

References
1.
Sakakida
,
T.
,
Endou
,
R.
,
Kawabata
,
M.
,
Yokota
,
H.
,
Fujiwaka
,
T.
,
Asada
,
Y.
, and
Suzuki
,
K.
,
2000
, “
Study on Seismic Design of Nuclear Power Plant Piping in Japan, Part 4: Analytical Evaluation of Piping Component Tests
,”
ASME PVP
,
407
, pp.
139
146
.
2.
Namita
,
H.
,
Suzuki
,
K.
,
Abe
,
H.
,
Ichihashi
,
I.
,
Shiratori
,
M.
,
Tai
,
K.
,
Iwata
,
K.
, and
Neb
,
A.
,
2003
, “
Seismic Proving Test of Eroded Piping (Status of Eroded Component and System Test)
,”
ASME
Paper No. PVP2003-2097. 10.1115/PVP2003-2097
3.
Urabe
,
Y.
,
Takahashi
,
K.
, and
Ando
,
K.
,
2012
, “
Low Cycle Fatigue Behavior and Seismic Assessment for Elbow Pipe With Local Wall Thinning
,”
ASME J. Pressure Vessel Technol.
,
134
(
4
), p.
041801
.10.1115/1.4005870
4.
Takahashi
,
K.
,
Matsuo
,
K.
,
Sato
,
K.
,
Ando
,
K.
,
Urabe
,
Y.
, and
Kasai
,
N.
,
2011
, “
Low Cycle Fatigue Behaviors Elbows With Local Wall Thinning Under Combined Bending and Internal Pressure
,”
ASME
Paper No. PVP2011-57322. 10.1115/PVP2011-57322
5.
Urabe
,
Y.
,
Takahashi
,
K.
,
Sato
,
K.
, and
Ando
,
K.
,
2013
, “
Low Cycle Fatigue Behavior and Seismic Assessment for Pipe Bends Having Local Wall Thinning—Influence of Internal Pressure
,”
ASME J. Pressure Vessel Technol.
,
135
(
4
), p.
041802
.10.1115/1.4024444
6.
Takahashi
,
K.
,
Matsuo
,
K.
,
Ando
,
K.
, and
Urabe
,
Y.
,
2014
, “
Estimation of Low Cycle Fatigue Life of Elbow Pipes Considering the Multi-Axial Stress Effect
,”
ASME J. Pressure Vessel Technol.
,
136
(4), p.
041405
.10.1115/1.4026903
7.
Ando
,
K.
,
Takahashi
,
K.
,
Matsuo
,
K.
, and
Urabe
,
Y.
,
2012
, “
Evaluation of Low Cycle Fatigue Life of Elbow Pipes Considering the Bi-Axial Stress Effect
,”
J. High Pressure Inst. Jpn.
,
50
(
4
), pp.
184
193
(in Japanese).
8.
ASME Boiler and Pressure Vessel Code Section III, Mandatory Appendices, Mandatory Appendix I
, Design Fatigue Curves, 2013.
9.
Manson
,
S. S.
,
1965
, “
Fatigue: A Complex Subject—Some Simple Approximations
,”
Exp. Mech.
,
5
(
7
), pp.
193
226
.10.1007/BF02321056
10.
Nakamura
,
I.
,
Ota
,
A.
, and
Shiratori
,
M.
,
2001
, “
Research on Seismic Safety Margin Evaluation Method Considering Degradation of Aged Equipments and Piping
,” Technical Note of the National Research Institute for Earth Science and Disaster Prevention, Vol. 220 (in Japanese).
11.
Miyazaki
,
K.
,
Nebu
,
K.
,
Kanno
,
S.
,
Ishiwata
,
M.
, and
Hasegawa
,
K.
,
2002
, “
Fracture Criterion of Carbon Steel Piping Containing Local Wall Thinning
,”
J. High Pressure Inst. Jpn.
,
40
(
2
), pp.
62
71
(in Japanese).
12.
Sato
,
K.
,
Ogino
,
K.
,
Takahashi
,
K.
,
Ando
,
K.
, and
Urabe
,
Y.
,
2010
, “
Influences of Internal Pressure and Overload on Low Cycle Fatigue Behaviors of Elbow Pipe With Local Wall Thinning
,”
ASME
Paper No. PVP2010-25571.10.1115/PVP2010-25571
You do not currently have access to this content.