Assessment of Failure Life Evaluation Methods for Structural Discontinuities with Fatigue and Creep-Fatigue Tests on Multi-Perforated Plate Made of Mod.9Cr-1Mo Steel

2021 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takano Masahito
Keyword(s):  
Fatigue Life ◽  
Perforated Plate ◽  
Estimation Method ◽  
Evaluation Methods ◽  
Fatigue Tests ◽  
Reduction Factor ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Number Of Cycles ◽  
Failure Life

Abstract This study compares and assesses the different fatgue and creep-fatigue life eveluation methods by performing tests of perforated plate made of Mod.9Cr-1Mo steel. Multi-perforated plate was subjected to mechanical cyclic loading at 550°C, and crack initiation and propagation on the surfaces of the holes were observed. A series of finite element analyses (FEA) were carried out to predict the number of cycles to failure by the several failure life evaluation methods, and these predictions were then compared with the test results. Several types of evaluation methods that use the elastic FEA were applied, namely the stress redistribution locus (SRL) method, simple elastic follow-up method. In addition to these, evaluation was also carried out using the results of inelastic FEA to compare these elastic FEA based estimation method. The comparisons indicate that, for all conditions tested, the SRL method provided a rational prediction of the fatigue and creep-fatigue life when ? = 1.6 was applied, where ? = 1.6 is the recommended reduction factor for this method in general use. A comparison of the SRL method and the results of the inelastic FEA indicated that the applicability of the value of factor ? in the SRL method depends on the elastic region remaining in the cross-section including the evaluated point and the spread in the plastically deformed region in the specimen.

Comparison of Creep-Fatigue Evaluation Methods With Notched Specimens Made of Mod.9Cr-1Mo Steel

2011 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takanori Karato ◽  
Sota Watanabe ◽  
Osamu Inoue ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fast Reactor ◽  
Evaluation Methods ◽  
Fatigue Tests ◽  
Test Results ◽  
Notched Specimens ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation

In a component design at elevated temperature, creep-fatigue is one of the most important failure modes, and assessment of creep-fatigue life in structural discontinuity is important issue to evaluate structural integrity of the components. Therefore a lot of creep-fatigue life evaluation methods were proposed until now. To compare and assess these evaluation methods, a series of creep-fatigue tests was carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo steel, which it is a candidate material for a primary and secondary heat transport system components of JSFR (Japan Sodium-cooled Fast Reactor). Mechanical creep-fatigue tests and thermal creep-fatigue tests were performed by using conventional uni-axial push-pull fatigue test machine and thermal gradient generating system with an induction heating coil. Stress concentration levels were adjusted by varying the diameters of notch roots in the both tests. In the test, creep-fatigue lives, crack initiation and propagation processes were observed by digital micro-scope and replica method. Besides those, a series of elastic Finite Element Analysis (FEA) were carried out to predict the number of cycles to failure by several creep-fatigue life evaluation methods. Then these predictions were compared with test results. Several types of evaluation methods which are stress redistribution locus (SRL) method, simple elastic follow-up method and the methods described in JSME FR (Fast Reactor) code were applied. The applicability and conservativeness of these methods were discussed. It was appeared that SRL method gave rational prediction of creep-fatigue life with conservativeness when the factor of κ = 1.6 was applied for all the conditions tested in this study. Comparison of SRL method and simple elastic follow-up method indicated that SRL method applied factor of κ = 1.6 gave the smallest creep-fatigue life in practicable stress level. JSME FR code gave an evaluation 70∼100 times conservative lives comparing with the test results.

Fatigue and Creep-Fatigue Life Evaluation of U-Shaped Bellows

1992 ◽  
Vol 114 (3) ◽  
pp. 280-291 ◽  
Author(s):  
K. Tsukimori ◽  
T. Yamashita ◽  
M. Kikuchi ◽  
K. Iwata ◽  
A. Imazu
Keyword(s):  
Fatigue Life ◽  
Evaluation Method ◽  
Strain Range ◽  
Creep Damage ◽  
Fatigue Tests ◽  
Reliable Operation ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation ◽  
Rational Evaluation

For the reliable operation of bellows under cyclic loadings at high temperatures, a rational evaluation method of life of bellows would be needed. Authors investigated simplified analysis methods for fatigue and creep-fatigue life prediction of U-shaped bellows considering inelasticity as well as various geometrical nonuniformity such as thickness and shape of convolutions. A conservative evaluation method of the strain range is developed, introducing three strain range amplification factors for nominal elastic strain range. Creep and relaxation behaviors of bellows are studied. Consequently, a new evaluation method of creep damage fractions is proposed which depends upon the relation between primary and secondary stresses. Fatigue and creep-fatigue tests are conducted and the validity of the present methods is discussed.

Stress and Strain Locus of Perforated Plate in Inelastic Deformation—Strain-Controlled Loading Case

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Osamu Watanabe ◽  
Bopit Bubphachot ◽  
Akihiro Matsuda ◽  
Taisuke Akiyama
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Cyclic Loading ◽  
Perforated Plate ◽  
Stress And Strain ◽  
Life Evaluation ◽  
Simplified Method ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation

Plastic strain of structures having stress concentration is estimated by using the simplified method or the finite element elastic solutions. As the simplified methods used in codes and standards, we can cite Neuber’s formula in the work by American Society of Mechanical Engineers (1995, “Boiler and Pressure Vessel Code,” ASME-Code, Section 3, Division 1, Subsection NH) and by Neuber (1961, “Theory of Stress Concentration for Shear Strained Prismatic Bodies With Arbitrary Nonlinear Stress-Strain Law,” ASME, J. Appl. Mech., 28, pp.544–550) and elastic follow-up procedure in the work by Japan Society of Mechanical Engineers [2005, “Rules on Design and Construction for Nuclear Power Plants, 2005, Division 2: Fast Breeder Reactor” (in Japanese)]. Also, we will cite stress redistribution locus (SRL) method recently proposed as the other simplified method in the work by Shimakawa et al. [2002, “Creep-Fatigue Life Evaluation Based on Stress Redistribution Locus (SRL) Method,” JPVRC Symposium 2002, JPVRC/EPERC/JPVRC Joint Workshop sponsored by JPVRC, Tokyo, Japan, pp. 87–95] ad by High Pressure Institute of Japan [2005, “Creep-Fatigue Life Evaluation Scheme for Ferritic Component at Elevated Temperature,” HPIS C 107 TR 2005 (in Japanese)]. In the present paper, inelastic finite element analysis of perforated plate, whose stress concentration is about 2.2–2.5, is carried out, and stress and strain locus in inelastic range by the detailed finite element solutions is investigated to compare accuracy of the simplified methods. As strain-controlled loading conditions, monotonic loading, cyclic loading, and cyclic loading having hold time in tension under strain-controlled loading are assumed. The inelastic strain affects significantly life evaluation of fatigue and creep-fatigue failure modes, and the stress and strain locus is discussed from the detailed inelastic finite element solutions.

scholarly journals Evaluation of Multiaxial Creep-fatigue Strength for High Chromium Steel under Non-proportional Loading

2019 ◽  
Vol 300 ◽  
pp. 07002
Author(s):  
Yuuki Kasamuta ◽  
Fumio Ogawa ◽  
Takamoto Itoh ◽  
Hiroyasu Tanigawa
Keyword(s):  
Chromium Steel ◽  
Fatigue Tests ◽  
Proportional Loading ◽  
High Chromium ◽  
Nuclear Fusion Reactor ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Strain Paths ◽  
Multiaxial Creep ◽  
Failure Life

This study discusses the result of creep-fatigue tests of a high-chromium steel, F82H which was designed as blanket structural materials of nuclear fusion reactor, carried out at room temperature to 823K in air. Strain paths applied were a push-pull loading and a circle loading in which normal and shear strain have 90 degree phase difference. The holding times used were 180 s and 600 s. Moreover, an evaluation of failure life by taking into account intensities of creep and non-proportionality is discussed based on both the life evaluation proposed by Itoh, et al and method of modified universal slopes. Availability of the equation for the life evaluation was confirmed by comparison with conventional universal slope method.

Comparison and Assessment of the Creep-Fatigue Evaluation Methods With Notched Specimen Made of Mod.9Cr-1Mo Steel

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takanori Karato ◽  
Sota Watanabe ◽  
Osamu Inoue ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Fast Reactor ◽  
Evaluation Methods ◽  
Test Machine ◽  
Test Results ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation

In components design at elevated temperature, creep-fatigue is one of the most important failure modes, and assessment of creep-fatigue life in structural discontinuities is an important issue in evaluating the integrity of components. Therefore, a lot of creep-fatigue life evaluation methods were proposed until now. To compare and assess the evaluation methods, a series of creep-fatigue test was carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo steel, which is a candidate material for primary and secondary heat transport system components of the Japan sodium-cooled fast reactor (JSFR). Mechanical creep-fatigue tests and thermal creep-fatigue test were performed by using a conventional uni-axial push–pull fatigue test machine and a thermal gradient generating system with an induction heating. The stress concentration levels were adjusted by varying the notch radius in the each test. The creep-fatigue lives, crack initiation, and propagation processes were monitored by a digital microscope and the replica method. A series of finite element analysis (FEA) was carried out to predict the number of cycles to failure by the several creep-fatigue life evaluation methods. Then, these predictions were compared with the test results. Several types of evaluation methods such are stress redistribution locus (SRL) method, simple elastic follow-up method and the methods described in the design and constriction code for fast reactor (FR) published by the Japan Society of Mechanical Engineers (JSME FRs code) were applied. Through the comparisons, it was appeared that SRL method gave rational conservative prediction of the creep-fatigue life when the factor of κ = 1.6 was applied for all conditions tested in this study. A comparison of SRL method and simple elastic follow-up method indicated that SRL method applied factor of κ = 1.6 gave the smallest creep-fatigue life in practicable stress range level. The JSME FRs code gave an evaluation 70–100 times conservative lives comparing with the test results.

Application of Ultrasonic Test on Creep-Fatigue Life Evaluation

2006 ◽  
Vol 321-323 ◽  
pp. 476-479
Author(s):  
Bum Joon Kim ◽  
Byeong Soo Lim ◽  
Sung Jin Song ◽  
Young H. Kim
Keyword(s):  
Fatigue Life ◽  
Power Plants ◽  
Hold Time ◽  
Ultrasonic Inspection ◽  
Fatigue Tests ◽  
Ultrasonic Test ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation ◽  
The Relationship

This work investigates the relationship between the creep-fatigue life and ultrasonic test of creep-fatigue damage. Under the creep-fatigue interaction, the main cause of life reduction is the initiation and growth of microvoid with increasing hold time. The number/size of microvoid/cavity, the fraction of cavity area varied with the hold time. Therefore, the life evaluation using the microvoid with the variation of hold time is very informative for safety of components in power plants. In this study, using the heat resisting alloy, P122 steel for USC (ultra super critical) power plant, the creep-fatigue tests with various hold times and their ultrasonic inspection were carried out for the purpose of evaluation for creep-fatigue life. The results obtained by Rayleigh surface wave of backscattered ultrasound were compared and analyzed with the experimental parameters. The good agreement between the experimental life and the predicted life was obtained.

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