Inherent variability of an experimental crack growth curve

2007 ◽  
Vol 29 (1) ◽  
pp. 66-76 ◽  
Author(s):  
F. Casciati ◽  
P. Colombi ◽  
L. Faravelli
Keyword(s):  
Crack Growth ◽  
Growth Curve ◽  
Crack Growth Curve

Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment

2004 ◽  
Author(s):  
Yuichiro Nomura ◽  
Kazuya Tsutsumi ◽  
Hiroshi Kanasaki ◽  
Naoki Chigusa ◽  
Kazuhiro Jotaki ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Stress Intensity Factor Range ◽  
Reference Curve ◽  
Pressurized Water ◽  
Crack Growth Curve

Although reference fatigue crack growth curves for austenitic stainless steels in air environments and boiling water reactor (BWR) environments were prescribed in JSME S NA1-2002, similar curves for pressurized water reactors (PWR) were not prescribed. In order to propose the reference curve in PWR environment, fatigue tests of austenitic stainless steels in simulated PWR primary water environment were carried out. According to the procedure to determine the reference fatigue crack growth curve of BWR, which of PWR is proposed. The reference fatigue crack growth curve in PWR environment have been determines as a function of stress intensity factor range, Temperature, load rising time and stress ratio.

A Flaw Tolerance Concept for Plant Maintenance Using Virtual Fatigue Crack Growth Curve

2013 ◽  
Author(s):  
Masayuki Kamaya ◽  
Takao Nakamura
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Growth Behavior ◽  
Plant Design ◽  
Flaw Tolerance ◽  
Plant Maintenance ◽  
Crack Growth Curve

Incorporation of the flaw tolerance concept in plant design and maintenance is discussed in order to consider the reduction in fatigue life due to the high-temperature water environment of class 1 components of NPPs. The flaw tolerance concept has been included in Section XI of the ASME BPVC. The structural factor (safety factor) for the flaw evaluation is considered in the stress, whereas it was considered in the design fatigue curve in Section III of the ASME BPVC. In order to apply the flaw tolerance concept to plant design and maintenance, it is necessary to assume the crack initiation and growth behavior. In this study, first, crack initiation and growth behavior during fatigue tests was reviewed and a relationship between the crack growth and fatigue life was quantified. Then, the safety factor was considered in the crack growth curve. It was shown that the crack size could be correlated to the usage factor and the flaw tolerance concept was reasonably considered in the plant maintenance by using the proposed virtual fatigue crack growth curve.

scholarly journals Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment

2003 ◽  
Vol 2003 (0) ◽  
pp. 917-918
Author(s):  
Yuichiro Nomura ◽  
Kazuya Tsutsumi ◽  
Hiroshi Kanasaki ◽  
Morihito Nakano ◽  
Kazuhiro Jotaki ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Crack Growth Curve

Probabilistic Analysis of Fatigue Crack Propagation Under Random Loading

1994 ◽  
Vol 116 (2) ◽  
pp. 216-225 ◽  
Author(s):  
W.-F. Wu ◽  
C. S. Shin ◽  
J.-J. Shen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Growth Curves ◽  
Experimental Result ◽  
Random Loading ◽  
Constant Loading ◽  
Statistical Variation ◽  
Crack Growth Curve

In order to predict the fatigue crack growth curve under random loading, an analytical model is proposed in this paper. In addition to the mean crack growth curve, the model also considers the statistical variation of the crack growth curves under the same nature of random loading, as well as the material reliability after certain loading cycles are applied. To check the applicability of the prediction model, several fatigue experiments are performed. After comparing the analytical result with the experimental result, the following conclusions are drawn. (i) Under the same mean value and standard deviation for the stress amplitudes, the fatigue crack growth curves are influenced by the probability density function of the stresses. (ii) An “equivalent constant loading” and a crack closure model lead to better prediction than any other model. (iii) The variation of the crack growth curves can be predicted accurately for shorter crack lengths and conservatively for longer crack lengths. (iv) The prediction of the statistical variation can be improved by modifying the definition of the equivalent constant loading. (v) Fatigue reliability can be reasonably estimated. The foregoing conclusions can be taken into consideration in the design of pressure vessels which are frequently subjected to transients of random nature.

Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment

2006 ◽  
Author(s):  
Yuichiro Nomura ◽  
Katsumi Sakaguchi ◽  
Hiroshi Kanasaki ◽  
Shigeki Suzuki
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Crack Growth Curve

Reference fatigue crack growth rate curves for austenitic stainless steels in pressurized water reactors (PWR) environments were prescribed in JSME S NA1-2004(1) in Japan. The reference fatigue crack growth curve in PWR environment had been determined as a function of stress intensity factor range, temperature, load rising time and stress ratio. In order to confirm the applicability of the reference fatigue crack growth rate curve under high stress ratio, low rising time and low stress intensity range, fatigue crack propagation tests of austenitic stainless steels 316, 316 weld metal, 304 and 304 weld metal were carried out. It is concluded that the reference fatigue crack growth curve in PWR environment is applicable to predict fatigue crack growth rate of this study test conditions.

Re-Evaluation of Fatigue Crack Growth Curve for Austenitic Stainless Steels in BWR Environment

2012 ◽  
Author(s):  
Masao Itatani ◽  
Takuya Ogawa ◽  
Chihiro Narazaki ◽  
Toshiyuki Saito
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Reference Curve ◽  
Growth Data ◽  
Crack Growth Curve ◽  
Confidential Limit

The Rules on Fitness-for-Service for Nuclear Power Plants of the Japan Society of Mechanical Engineers (JSME Code) has the reference fatigue crack growth curve for austenitic stainless steels in BWR environment. This reference curve was determined as the upper bound of crack growth data excluding the outlier data. However, the other reference curves for fatigue crack growth rate such as austenitic stainless steels and ferritic steels in air environment and ferritic steels in water environment in the ASME Boiler and Pressure Vessel Code, Section XI and the JSME Code, austenitic stainless steels in PWR environment in the JSME Code and Ni-base alloys in PWR environment in the JSME Code Case are determined based on the 95% upper confidential limit by statistic data treatment. In the present study, the fatigue crack growth data of austenitic stainless steels in BWR environment were re-evaluated statistically. It was found that the current reference curve almost coincides with 95% upper confidential limit of fatigue crack growth data in the Paris region. Consequently, the current reference fatigue crack growth curve for austenitic stainless steels in BWR environment in the JSME Code can be regarded to stand on the same technical bases with other reference fatigue crack growth curves. Furthermore, the authors proposed to extend applicable upper bound of load rising time tr from 1000 s to 32000 s.

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