Effects of Load Sequence on Fatigue Crack Growth in Pressure Vessels

2010 ◽  
Vol 160-162 ◽  
pp. 1217-1222 ◽  
Author(s):  
Shahrum Abdullah ◽  
S.M. Beden ◽  
Ahmad Kamal Ariffin ◽  
Zulkifli Mohd Nopiah
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Test Data ◽  
Life Prediction ◽  
Power Plants ◽  
Pressure Vessels ◽  
Low Alloy Steels ◽  
Variable Amplitude

Low alloy steels such as ASTM A508 and A533 and their equivalent materials have been extensively applied in fabricating pressure vessels due to their relatively excellent mechanical properties and moderately good weldability. The integrity of such materials governs the safety of the power plants. These vessels mainly are subjected to random loading in service and the load cycle interactions can have a significant effect in fatigue crack growth. Studying of fatigue crack growth rate and fatigue life calculation under spectrum loading is important for the reliable life prediction of vessels. Many models have been proposed, but as yet no universal model exists. In this paper, a fatigue life predicted under various load spectra, using three different fatigue crack growth models namely the Austen, modified Forman and NASGRO models. These models are validated with fatigue crack growth test data under various variable amplitude loadings. This application is performed with aids of three-point bend specimens. The results show clearly the load sequences effect and the predicted results agree with some discrepancies between the different models as well as with the test data. Neglecting, the cycle interaction effects in fatigue calculation under variable amplitude loading lead to invalid life prediction.

Observing Load Sequence Effects on Simulated and Experimental Fatigue Crack Growth Occurrence

2011 ◽  
Vol 462-463 ◽  
pp. 489-494 ◽  
Author(s):  
S.M. Beden ◽  
Shahrum Abdullah ◽  
Ahmad Kamal Ariffin ◽  
Nawar A. Kadhim
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Test Data ◽  
Growth Models ◽  
Load Cycle ◽  
Engineering Structures ◽  
Variable Amplitude Loading ◽  
Variable Amplitude

Load cycle interactions can have a significant effect in fatigue crack growth (FCG) under variable amplitude loading. Studying of FCG and fatigue life calculation under spectrum loading is important for the reliable life prediction of engineering structures. Many models have been proposed, but yet no universal model exists. In this paper, a fatigue life predicted under various load spectra, using three different fatigue crack growth models namely, the Austen, modified Forman and NASGRO models. These models are validated with fatigue crack growth test data under various amplitude loadings. This application is performed with aids of three-point bend specimens of ASTM A533 steel material. The results clearly show the load sequences effect and the predicted results agree with some discrepancies between the different models as well as with the test data. Thus, neglecting the effect of cycle interaction in fatigue calculations under variable amplitude loading can lead to invalid life predictions.

Proof-Test-Based Life Prediction of High-Toughness Pressure Vessels

1996 ◽  
Vol 118 (1) ◽  
pp. 86-94 ◽  
Author(s):  
T. L. Panontin ◽  
M. R. Hill
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Life Prediction ◽  
Crack Size ◽  
Initial Crack ◽  
Pressure Vessels ◽  
Operating Pressure ◽  
High Toughness

The paper examines the problems associated with applying proof-test-based life prediction to vessels made of high-toughness metals. Two A106 Gr B pipe specimens containing long, through-wall, circumferential flaws were tested. One failed during hydrostatic testing and the other during tension-tension cycling following a hydrostatic test. Quantitative fractography was used to verify experimentally obtained fatigue crack growth rates and a variety of LEFM and EPFM techniques were used to analyze the experimental results. The results show that: plastic collapse analysis provides accurate predictions of screened (initial) crack size when the flow stress is determined experimentally; LEFM analysis underestimates the crack size screened by the proof test and overpredicts the subsequent fatigue life of the vessel when retardation effects are small (i.e., low proof levels); and, at a high proof-test level 2.4 × operating pressure), the large retardation effect on fatigue crack growth due to the overload overwhelmed the deleterious effect on fatigue life from stable tearing during the proof test and alleviated the problem of screening only long cracks due to the high toughness of the metal.

scholarly journals Uncertainty Modeling of Fatigue Crack Growth and Probabilistic Life Prediction for Welded Joints of Nuclear Stainless Steel

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3192 ◽  
Author(s):  
Haijun Chang ◽  
Mengling Shen ◽  
Xiaohua Yang ◽  
Junxia Hou
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Welded Joints ◽  
Life Prediction ◽  
Power Plants ◽  
Test System

Welded joints are widely used in the pipeline connection of nuclear power plants. Defects in these joints are an important factor leading to the failure of welded joints. It is critical to study the fatigue crack growth and life prediction methods for the welded joints with defects, to reduce their likelihood. In this paper, we present our study of the uncertainty of fatigue crack propagation and probabilistic life prediction for welded joints of nuclear stainless steel. The standard compact tension (CT) specimens were fabricated according to the American Society for Testing and Materials (ASTM) standard. Fatigue crack propagation tests with different stress ratios were performed on CT specimens, using the Mei Te Si (MTS) fatigue test system. A fatigue crack propagation rate model considering the uncertainty of material parameters, and based on the Paris formula and crack propagation experimental data, was established. A probabilistic life prediction method based on Monte Carlo simulation was developed. The fatigue crack propagation prediction result of a CT specimen was compared with the actual tested result, to verify the effectiveness of the proposed method. Finally, the method was applied to an embedded elliptical crack in welded joints of nuclear stainless steel, to predict the fatigue crack growth life and evaluate the reliability.

Fatigue life prediction based on an equivalent initial flaw size approach and a new normalized fatigue crack growth model

2016 ◽  
Vol 69 ◽  
pp. 15-28 ◽  
Author(s):  
J.A.F.O. Correia ◽  
S. Blasón ◽  
A.M.P. De Jesus ◽  
A.F. Canteli ◽  
P.M.G.P. Moreira ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Model ◽  
Life Prediction ◽  
Flaw Size ◽  
Fatigue Life Prediction ◽  
Crack Growth Model

Introduction of Technical Document in Japan for Safe Use of Ground Storage Vessels Made of Low Alloy Steels for Hydrogen Refueling Stations

2018 ◽  
Author(s):  
Hajime Fukumoto ◽  
Yoru Wada ◽  
Hisao Matsunaga ◽  
Takeru Sano ◽  
Hiroshi Kobayashi
Keyword(s):  
Tensile Strength ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Pressure Vessels ◽  
Hydrogen Gas ◽  
Low Alloy Steels ◽  
Technical Document ◽  
Performance Requirements ◽  
Alloy Steels

As is well known, low alloy steels are widely used as materials for high pressure vessels because of their high tensile strength and reasonable price, but also show severe hydrogen embrittlement. Therefore, in 2016, the authors introduced a scenario for the safe use of low alloy steels in highly pressurized hydrogen gas as a “Guideline” at ASME PVP 2016 [1]. Following discussions with stakeholders and experts in recent years, we published Technical Document (TD) as an industrial standard prior to regulation, on the safe use of ground storage vessels made of low alloy steels in Hydrogen Refueling Stations (HRSs) based on performance requirements. This article presents an outline of the TD describing the required types of testing as performance requirements for confirming the good hydrogen compatibility of low alloy steels, such as controlling tensile strength in an appropriate range, confirming leak-before-break, determining the life of ground storage vessels by fatigue testing and determining the inspection term by fatigue crack growth analysis using the fatigue crack growth rate in highly pressurized hydrogen.

Predicting Fatigue Crack Growth and Fatigue Life Under Variable Amplitude Loading

2010 ◽  
Vol 2010 (2) ◽  
pp. 37-51
Author(s):  
Michal Jasztal ◽  
Dorota Kocanda ◽  
Henryk Tomaszek
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Probabilistic Approach ◽  
Alloy Sheet ◽  
Load Spectrum ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Life Estimation

Predicting Fatigue Crack Growth and Fatigue Life Under Variable Amplitude Loading A probabilistic approach to the description of fatigue crack growth and fatigue life estimation of a component subjected to variable amplitude loading is presented in the paper. The core of the model is a differential equation originated from the Paris formula. In order to consider the influence of overload-underload cycles existing in an exploitive load spectrum on crack growth rate for an aeronautical aluminum alloy sheet, the modified Willenborg retardation model was applied.

Effect of Specimen Size on Elastic-Plastic Fatigue Crack Growth and Resistance Curve of Carbon Steel

2014 ◽  
Author(s):  
Junya Ikegami ◽  
Motoki Taniguchi ◽  
Masahiro Takanashi ◽  
Shota Hasunuma ◽  
Takeshi Ogawa
Keyword(s):  
Fatigue Crack ◽  
Carbon Steel ◽  
Cyclic Loading ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Power Plants ◽  
Pressure Vessels ◽  
Crack Growth Behavior ◽  
Load Line ◽  
Load Line Displacement

In order to investigate the ultimate strength of structures and components under an unexpected huge earthquake, it is necessary to understand the final fracture condition under static and cyclic loadings. This study compared the crack growth behavior under monotonic and cyclic loading conditions for carbon steel SGV410 used for pressure vessels in nuclear power plants. Fatigue tests were carried out for CT specimens 50 mm wide (1CT), 75 mm wide (1.5CT) and 100 mm wide (2CT) using three kinds of test methods, namely monotonic loading (ML), load line displacement amplitude increasing (V-inc.) and fatigue crack growth (FCG) tests. For the FCG tests, the maximum load was kept constant under cyclic loading with full unloading (R = 0), fully reversed loading (R = −1) and fully reversing the load line displacement (R = −1.5) and the crack growth characteristics were evaluated by the fracture mechanics approach.

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